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Define Initial Exec to Local Exec TLS relaxation #122
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This is being discussed in an LLVM issue, I believe that this is the correct place to discuss this issue. Dropping this feature means an ABI change, and we froze the ABI when we upstreamed glibc. However, since we are proposing to change the compiler, there won't be any backwards compatible problem as long as binutils and glibc continue to support the feature for old libraries compiled with the feature. This would mean marking the feature as deprecated instead of immediately dropping it from the ABI, and then sometime later marking it as obsolete. Thus compilers should stop generating it immediately, but linkers and dynamic linkers may need to continue to support it as long as we have old libraries using it. There is support in glibc for TLS copy relocs, in the sysdeps/riscv/dl-machine.h file, there is a R_RISCV_COPY case, which has a comment This feature was added to the ABI before I started doing RISC-V work, and I don't know why it is there. I agree that it is an odd feature, and one that no other architecture target supports. But I don't have an opinion about it, as this is outside my primary area of expertise, other than the fact that if we want to drop this we need to deprecate it first as we do have existing systems built using this feature. There do seem to be some good arguments presented for why it should be deprecated. |
There are good reasons not to have this "feature" (TLS copy relocs). Copy relocation in general (not just TLS) are problematic in that they can significantly increase memory usage (for non-TLS globals, a worst-case involves copying a large const table from shared text in a shared library to writable data in each instance of an application using the library) and make size of structs/arrays into ABI between the library and application linked to it, thereby precluding extensibility by adding to the end of a struct or enlarging an array. For TLS, the memory usage issue is magnified by the waste being per-thread rather than per-process (each thread now reserves space for two copies of the copy-reloc'd TLS). And whereas it's been long-known that exporting global structs/arrays from shared libraries could be problematic because of copy relocations, ones with thread-local storage have never before had this problem on any existing architecture. Programmers could rightly use them in the presumed-to-be-extensible way without ABI breakage. Doing this with copy relocations on riscv breaks that property. Further, TLS with copy relocations clashes with protected-visibility on TLS data. For global data and functions, protected visibility already had poorly-defined semantics and was not reliable, due to copy relocations and PLT definitions. However for TLS, protected visibility presumably did work everywhere. Introducing copy relocations broke that. I don't think removing copy relocations here is serious breakage. Tooling could keep support for existing programs with them, but it looks like, due to binutils bug 23825, affected binaries were broken anyway. Moreover musl has not supported copy relocations and I would like to not start. I've included the patch from PR 118 above in musl-cross-make for now and hope that will be the upstream decision. |
@aswaterman @palmer-dabbelt Do you have any comments here? Do you know why these TLS copy relocs are present? |
Yes, it was my apparently naive solution to make LE TLS relocs against extern symbols work. I didn't realize emitting IE relocs and relaxing them was a superior solution. The copy relocs seemed to work and produce decent code, so I never revisited it. With the benefit of hindsight, I would've done things differently. I think we should continue supporting the copy relocs in binutils and the dynamic linker for backwards compatibility, but change GCC to stop emitting them, and add IE -> LE relaxation in binutils. |
I'm happy with that course of action. From my side (for musl) I'll just leave them unsupported since they have never worked in the past (no code in ldso to do them) and we now have the gcc patches in place to avoid it. |
That sounds like a good plan for musl. |
Looks like the binutils bug fix made it into 2.33, which means we can't just say "every binary with copy relocs is broken so we can remove it from the ABI". Given that, I think the best way forward here is to say the old scheme is deprecated. That'll allow us to avoid adding support to new projects (ie, musl) but we'll need to keep around support for anything that may have worked in the past (ie, glibc). |
I wasn't aware that the fix in binutils was already working right, since the issue on the tracker is still open. Indeed it may need to be supported indefinitely into the future on glibc if that's the case. Can the fix on the GCC side (not emitting local-exec here) be fast-tracked to make it into the next GCC release so that we at least minimize the proliferation of the problem? It would be nice not to be worrying many years down the line that folks might still have riscv toolchains where TLS causes the copy-reloc-related ABI issues with libraries. |
@jim-wilson knows better than I do about both of those, as he's the one who wrote the binutils patch and posted the WIP GCC branch. AFIAK we don't know of any brokenness with the binutils patch, but IIRC the goal was just to squash the glibc test suite failure so it's not like anyone's looked that closely. |
The binutils bug report is still open because I think there is a better way to fix it that I haven't tried yet, which is stuck on my to do list with hundreds of other things. But it is working. It fixed 2 glibc testsuite failures, and is in a few distros already. And has been in riscv-gnu-toolchain for a while. The gcc patch is trivial. We can add it anytime. I'll want to make sure there are no binutils/gcc/glibc testsuite regressions but that is just some cpu time for builds. My riscv machine is tied up at the moment tryinjg to reproduce Andreas Schwab's binutils bug report for a llvm builds. I think the hard part now is that someone has to write a patch to fix the text in this document. |
Summary: Forcing Local Exec TLS requires the use of copy relocations. Copy relocations need special handling in the runtime linker when being used against TLS symbols, which is present in glibc, but not in FreeBSD nor musl, and so cannot be relied upon. Moreover, copy relocations are a hack that embed the size of an object in the ABI when it otherwise wouldn't be, and break protected symbols (which are expected to be DSO local), whilst also wasting space, thus they should be avoided whenever possible. As discussed in D70398, RISC-V should move away from forcing Local Exec, and instead use Initial Exec like other targets, with possible linker relaxation to follow. The RISC-V GCC maintainers also intend to adopt this more-conventional behaviour (see riscv-non-isa/riscv-elf-psabi-doc#122). Reviewers: asb, MaskRay Reviewed By: MaskRay Subscribers: emaste, krytarowski, hiraditya, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, llvm-commits, bsdjhb Tags: #llvm Differential Revision: https://reviews.llvm.org/D70649
[RISCV] Don't force Local Exec TLS for non-PIC Summary: Forcing Local Exec TLS requires the use of copy relocations. Copy relocations need special handling in the runtime linker when being used against TLS symbols, which is present in glibc, but not in FreeBSD nor musl, and so cannot be relied upon. Moreover, copy relocations are a hack that embed the size of an object in the ABI when it otherwise wouldn't be, and break protected symbols (which are expected to be DSO local), whilst also wasting space, thus they should be avoided whenever possible. As discussed in D70398, RISC-V should move away from forcing Local Exec, and instead use Initial Exec like other targets, with possible linker relaxation to follow. The RISC-V GCC maintainers also intend to adopt this more-conventional behaviour (see riscv-non-isa/riscv-elf-psabi-doc#122). Reviewers: asb, MaskRay Reviewed By: MaskRay Subscribers: emaste, krytarowski, hiraditya, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, llvm-commits, bsdjhb Tags: #llvm Differential Revision: https://reviews.llvm.org/D70649 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC after: 1 week X-MFC-With: r353358 git-svn-id: svn+ssh://svn.freebsd.org/base/head@356330 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
[RISCV] Don't force Local Exec TLS for non-PIC Summary: Forcing Local Exec TLS requires the use of copy relocations. Copy relocations need special handling in the runtime linker when being used against TLS symbols, which is present in glibc, but not in FreeBSD nor musl, and so cannot be relied upon. Moreover, copy relocations are a hack that embed the size of an object in the ABI when it otherwise wouldn't be, and break protected symbols (which are expected to be DSO local), whilst also wasting space, thus they should be avoided whenever possible. As discussed in D70398, RISC-V should move away from forcing Local Exec, and instead use Initial Exec like other targets, with possible linker relaxation to follow. The RISC-V GCC maintainers also intend to adopt this more-conventional behaviour (see riscv-non-isa/riscv-elf-psabi-doc#122). Reviewers: asb, MaskRay Reviewed By: MaskRay Subscribers: emaste, krytarowski, hiraditya, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, llvm-commits, bsdjhb Tags: #llvm Differential Revision: https://reviews.llvm.org/D70649 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC after: 1 week X-MFC-With: r353358
[RISCV] Don't force Local Exec TLS for non-PIC Summary: Forcing Local Exec TLS requires the use of copy relocations. Copy relocations need special handling in the runtime linker when being used against TLS symbols, which is present in glibc, but not in FreeBSD nor musl, and so cannot be relied upon. Moreover, copy relocations are a hack that embed the size of an object in the ABI when it otherwise wouldn't be, and break protected symbols (which are expected to be DSO local), whilst also wasting space, thus they should be avoided whenever possible. As discussed in D70398, RISC-V should move away from forcing Local Exec, and instead use Initial Exec like other targets, with possible linker relaxation to follow. The RISC-V GCC maintainers also intend to adopt this more-conventional behaviour (see riscv-non-isa/riscv-elf-psabi-doc#122). Reviewers: asb, MaskRay Reviewed By: MaskRay Subscribers: emaste, krytarowski, hiraditya, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, llvm-commits, bsdjhb Tags: #llvm Differential Revision: https://reviews.llvm.org/D70649 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC after: 1 week X-MFC-With: r353358 git-svn-id: https://svn.freebsd.org/base/head@356330 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Merge commit 41449c58c from llvm git (by Roger Ferrer Ibanez): [RISCV] Fix evaluation of %pcrel_lo The following testcase function: .Lpcrel_label1: auipc a0, %pcrel_hi(other_function) addi a1, a0, %pcrel_lo(.Lpcrel_label1) .p2align 2 # Causes a new fragment to be emitted .type other_function,@function other_function: ret exposes an odd behaviour in which only the %pcrel_hi relocation is evaluated but not the %pcrel_lo. $ llvm-mc -triple riscv64 -filetype obj t.s | llvm-objdump -d -r - <stdin>: file format ELF64-riscv Disassembly of section .text: 0000000000000000 function: 0: 17 05 00 00 auipc a0, 0 4: 93 05 05 00 mv a1, a0 0000000000000004: R_RISCV_PCREL_LO12_I other_function+4 0000000000000008 other_function: 8: 67 80 00 00 ret The reason seems to be that in RISCVAsmBackend::shouldForceRelocation we only consider the fragment but in RISCVMCExpr::evaluatePCRelLo we consider the section. This usually works but there are cases where the section may still be the same but the fragment may be another one. In that case we end forcing a %pcrel_lo relocation without any %pcrel_hi. This patch makes RISCVAsmBackend::shouldForceRelocation use the section, if any, to determine if the relocation must be forced or not. Differential Revision: https://reviews.llvm.org/D60657 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356330: Merge commit da7b129b1 from llvm git (by James Clarke): [RISCV] Don't force Local Exec TLS for non-PIC Summary: Forcing Local Exec TLS requires the use of copy relocations. Copy relocations need special handling in the runtime linker when being used against TLS symbols, which is present in glibc, but not in FreeBSD nor musl, and so cannot be relied upon. Moreover, copy relocations are a hack that embed the size of an object in the ABI when it otherwise wouldn't be, and break protected symbols (which are expected to be DSO local), whilst also wasting space, thus they should be avoided whenever possible. As discussed in D70398, RISC-V should move away from forcing Local Exec, and instead use Initial Exec like other targets, with possible linker relaxation to follow. The RISC-V GCC maintainers also intend to adopt this more-conventional behaviour (see riscv-non-isa/riscv-elf-psabi-doc#122). Reviewers: asb, MaskRay Reviewed By: MaskRay Subscribers: emaste, krytarowski, hiraditya, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, llvm-commits, bsdjhb Tags: #llvm Differential Revision: https://reviews.llvm.org/D70649 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356331: Merge commit c6b09bff5 from llvm git (by Luís Marques): [RISCV] Fix wrong CFI directives Summary: Removes CFI CFA directives that could incorrectly propagate beyond the basic block they were inteded for. Specifically it removes the epilogue CFI directives. See the branch_and_tail_call test for an example of the issue. Should fix the stack unwinding issues caused by the incorrect directives. Reviewers: asb, lenary, shiva0217 Reviewed By: lenary Tags: #llvm Differential Revision: https://reviews.llvm.org/D69723 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356332: Merge commit d7be3eab5 from llvm git (by Luís Marques): [RISCV] Handle fcopysign(f32, f64) and fcopysign(f64, f32) Summary: Adds tablegen patterns to explicitly handle fcopysign where the magnitude and sign arguments have different types, due to the sign value casts being removed the by DAGCombiner. Support for RV32IF follows in a separate commit. Adds tests for all relevant scenarios except RV32IF. Reviewers: lenary Reviewed By: lenary Tags: #llvm Differential Revision: https://reviews.llvm.org/D70678 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356333: Merge commit 189b7393d from llvm git (by John Baldwin): [lld][RISCV] Use an e_flags of 0 if there are only binary input files. Summary: If none of the input files are ELF object files (for example, when generating an object file from a single binary input file via "-b binary"), use a fallback value for the ELF header flags instead of crashing with an assertion failure. Reviewers: MaskRay, ruiu, espindola Reviewed By: MaskRay, ruiu Subscribers: kevans, grimar, emaste, arichardson, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, llvm-commits, jrtc27 Tags: #llvm Differential Revision: https://reviews.llvm.org/D71101 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb
[RISCV] Don't force Local Exec TLS for non-PIC Summary: Forcing Local Exec TLS requires the use of copy relocations. Copy relocations need special handling in the runtime linker when being used against TLS symbols, which is present in glibc, but not in FreeBSD nor musl, and so cannot be relied upon. Moreover, copy relocations are a hack that embed the size of an object in the ABI when it otherwise wouldn't be, and break protected symbols (which are expected to be DSO local), whilst also wasting space, thus they should be avoided whenever possible. As discussed in D70398, RISC-V should move away from forcing Local Exec, and instead use Initial Exec like other targets, with possible linker relaxation to follow. The RISC-V GCC maintainers also intend to adopt this more-conventional behaviour (see riscv-non-isa/riscv-elf-psabi-doc#122). Reviewers: asb, MaskRay Reviewed By: MaskRay Subscribers: emaste, krytarowski, hiraditya, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, llvm-commits, bsdjhb Tags: #llvm Differential Revision: https://reviews.llvm.org/D70649 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC after: 1 week X-MFC-With: r353358
Merge commit 41449c58c from llvm git (by Roger Ferrer Ibanez): [RISCV] Fix evaluation of %pcrel_lo The following testcase function: .Lpcrel_label1: auipc a0, %pcrel_hi(other_function) addi a1, a0, %pcrel_lo(.Lpcrel_label1) .p2align 2 # Causes a new fragment to be emitted .type other_function,@function other_function: ret exposes an odd behaviour in which only the %pcrel_hi relocation is evaluated but not the %pcrel_lo. $ llvm-mc -triple riscv64 -filetype obj t.s | llvm-objdump -d -r - <stdin>: file format ELF64-riscv Disassembly of section .text: 0000000000000000 function: 0: 17 05 00 00 auipc a0, 0 4: 93 05 05 00 mv a1, a0 0000000000000004: R_RISCV_PCREL_LO12_I other_function+4 0000000000000008 other_function: 8: 67 80 00 00 ret The reason seems to be that in RISCVAsmBackend::shouldForceRelocation we only consider the fragment but in RISCVMCExpr::evaluatePCRelLo we consider the section. This usually works but there are cases where the section may still be the same but the fragment may be another one. In that case we end forcing a %pcrel_lo relocation without any %pcrel_hi. This patch makes RISCVAsmBackend::shouldForceRelocation use the section, if any, to determine if the relocation must be forced or not. Differential Revision: https://reviews.llvm.org/D60657 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356330: Merge commit da7b129b1 from llvm git (by James Clarke): [RISCV] Don't force Local Exec TLS for non-PIC Summary: Forcing Local Exec TLS requires the use of copy relocations. Copy relocations need special handling in the runtime linker when being used against TLS symbols, which is present in glibc, but not in FreeBSD nor musl, and so cannot be relied upon. Moreover, copy relocations are a hack that embed the size of an object in the ABI when it otherwise wouldn't be, and break protected symbols (which are expected to be DSO local), whilst also wasting space, thus they should be avoided whenever possible. As discussed in D70398, RISC-V should move away from forcing Local Exec, and instead use Initial Exec like other targets, with possible linker relaxation to follow. The RISC-V GCC maintainers also intend to adopt this more-conventional behaviour (see riscv-non-isa/riscv-elf-psabi-doc#122). Reviewers: asb, MaskRay Reviewed By: MaskRay Subscribers: emaste, krytarowski, hiraditya, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, llvm-commits, bsdjhb Tags: #llvm Differential Revision: https://reviews.llvm.org/D70649 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356331: Merge commit c6b09bff5 from llvm git (by Luís Marques): [RISCV] Fix wrong CFI directives Summary: Removes CFI CFA directives that could incorrectly propagate beyond the basic block they were inteded for. Specifically it removes the epilogue CFI directives. See the branch_and_tail_call test for an example of the issue. Should fix the stack unwinding issues caused by the incorrect directives. Reviewers: asb, lenary, shiva0217 Reviewed By: lenary Tags: #llvm Differential Revision: https://reviews.llvm.org/D69723 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356332: Merge commit d7be3eab5 from llvm git (by Luís Marques): [RISCV] Handle fcopysign(f32, f64) and fcopysign(f64, f32) Summary: Adds tablegen patterns to explicitly handle fcopysign where the magnitude and sign arguments have different types, due to the sign value casts being removed the by DAGCombiner. Support for RV32IF follows in a separate commit. Adds tests for all relevant scenarios except RV32IF. Reviewers: lenary Reviewed By: lenary Tags: #llvm Differential Revision: https://reviews.llvm.org/D70678 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356333: Merge commit 189b7393d from llvm git (by John Baldwin): [lld][RISCV] Use an e_flags of 0 if there are only binary input files. Summary: If none of the input files are ELF object files (for example, when generating an object file from a single binary input file via "-b binary"), use a fallback value for the ELF header flags instead of crashing with an assertion failure. Reviewers: MaskRay, ruiu, espindola Reviewed By: MaskRay, ruiu Subscribers: kevans, grimar, emaste, arichardson, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, llvm-commits, jrtc27 Tags: #llvm Differential Revision: https://reviews.llvm.org/D71101 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb git-svn-id: https://svn.freebsd.org/base/stable/12@356469 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Summary: Forcing Local Exec TLS requires the use of copy relocations. Copy relocations need special handling in the runtime linker when being used against TLS symbols, which is present in glibc, but not in FreeBSD nor musl, and so cannot be relied upon. Moreover, copy relocations are a hack that embed the size of an object in the ABI when it otherwise wouldn't be, and break protected symbols (which are expected to be DSO local), whilst also wasting space, thus they should be avoided whenever possible. As discussed in D70398, RISC-V should move away from forcing Local Exec, and instead use Initial Exec like other targets, with possible linker relaxation to follow. The RISC-V GCC maintainers also intend to adopt this more-conventional behaviour (see riscv-non-isa/riscv-elf-psabi-doc#122). Reviewers: asb, MaskRay Reviewed By: MaskRay Subscribers: emaste, krytarowski, hiraditya, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, llvm-commits, bsdjhb Tags: #llvm Differential Revision: https://reviews.llvm.org/D70649
9.0.1 final release c1a0a213378a458fbea1a5c77b315c7dce08fd05, and a number of follow-ups. MFC r355948: Bootstrap mergeinfo for contrib/llvm-project Merge (record-only) the following paths to contrib/llvm-project: * ^/vendor/llvm-project/master * ^/vendor/llvm-project/release-8.x * ^/vendor/llvm-project/release-9.x MFC r355951: Merge empty dir updates from r355950 in vendor/llvm-project. MFC r355957: Merge diff elimination updates from r355953 into vendor/llvm-project. MFC r355959: Consolidate FREEBSD-Xlist files of different llvm sub-projects into one. MFC r356004: Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp 9.0.1 final release c1a0a213378a458fbea1a5c77b315c7dce08fd05. Release notes for llvm, clang, lld and libc++ 9.0.1 will become available here: https://releases.llvm.org/9.0.1/docs/ReleaseNotes.html https://releases.llvm.org/9.0.1/tools/clang/docs/ReleaseNotes.html https://releases.llvm.org/9.0.1/tools/lld/docs/ReleaseNotes.html https://releases.llvm.org/9.0.1/projects/libcxx/docs/ReleaseNotes.html PR: 240629 MFC r356005: Merge commit f97936fab from llvm git (by Eric Fiselier): [libc++] Cleanup and enable multiple warnings. Too many warnings are being disabled too quickly. Warnings are important to keeping libc++ correct. This patch re-enables two warnings: -Wconstant-evaluated and -Wdeprecated-copy. In future, all warnings disabled for the test suite should require an attached bug. The bug should state the plan for re-enabling that warning, or a strong case why it should remain disabled. This should fix a number of new g++ 9 warnings. Requested by: rlibby MFC r356100: Merge commit d3aeac8e2 from llvm git (by Justin Hibbits) [PowerPC] Only use PLT annotations if using PIC relocation model Summary: The default static (non-PIC, non-PIE) model for 32-bit powerpc does not use @plt annotations and relocations in GCC. LLVM shouldn't use @plt annotations either, because it breaks secure-PLT linking with (some versions of?) GNU LD. Update the available-externally.ll test to reflect that default mode should be the same as the static relocation, by using the same check prefix. Reviewed by: sfertile Differential Revision: https://reviews.llvm.org/D70570 Reviewed by: jhibbits Differential Revision: https://reviews.freebsd.org/D22913 MFC r356104 (by jhibbits): [PowerPC] enable atomic.c in compiler_rt and do not check and forces lock/lock_free decisions in compiled time Summary: Enables atomic.c in compiler_rt and forces clang to not emit a call for runtime decision about lock/lock_free. At compiling time, if clang can't decide if atomic operation can be lock free, it emits calls to external functions like `__atomic_is_lock_free`, `__c11_atomic_is_lock_free` and `__atomic_always_lock_free`, postponing decision to a runtime check. According to LLVM code documentation, the mechanism exists due to differences between x86_64 processors that can't be decided at runtime. On PowerPC and PowerPCSPE (32 bits), we already know in advance it can't be lock free, so we force the decision at compile time and avoid having to implement it in an external library. This patch was made after 32 bit users testing the PowePC32 bit ISO reported llvm could not be compiled with in-base llvm due to `__atomic_load8` not implemented. Submitted by: alfredo.junior_eldorado.org.br Reviewed by: jhibbits, dim Differential Revision: https://reviews.freebsd.org/D22549 MFC r356112 (by jhibbits): [PowerPC64] Starting from FreeBSD 13.0, default to ELFv2 ABI This changes the LLVM default powerpc64 ABI to ELFv2, if target OS is FreeBSD >= 13.0 This will also be sent upstream. Submitted by: alfredo.junior_eldorado.org.br Reviewed by: dim, luporl Relnotes: YES Differential Revision: https://reviews.freebsd.org/D20383 MFC r356256: Merge commit 468a0cb5f from llvm git (by Craig Topper): [X86] Add X87 FCMOV support to X86FlagsCopyLowering. Fixes PR44396 Merge commit 86f48999f from llvm git (by Craig Topper): [X86] Fix typo in getCMovOpcode. The 64-bit HasMemoryOperand line was using CMOV32rm instead of CMOV64rm. Not sure how to test this. We have no test coverage that passes true for HasMemoryOperand. This fixes 'Assertion failed: (MI.findRegisterDefOperand(X86::EFLAGS) && "Expected a def of EFLAGS for this instruction!"), function runOnMachineFunction' when compiling the misc/gpsim port for i386. Reported by: yuri Upstream PR: https://bugs.llvm.org/show_bug.cgi?id=44396 MFC r356329: Merge commit 41449c58c from llvm git (by Roger Ferrer Ibanez): [RISCV] Fix evaluation of %pcrel_lo The following testcase function: .Lpcrel_label1: auipc a0, %pcrel_hi(other_function) addi a1, a0, %pcrel_lo(.Lpcrel_label1) .p2align 2 # Causes a new fragment to be emitted .type other_function,@function other_function: ret exposes an odd behaviour in which only the %pcrel_hi relocation is evaluated but not the %pcrel_lo. $ llvm-mc -triple riscv64 -filetype obj t.s | llvm-objdump -d -r - <stdin>: file format ELF64-riscv Disassembly of section .text: 0000000000000000 function: 0: 17 05 00 00 auipc a0, 0 4: 93 05 05 00 mv a1, a0 0000000000000004: R_RISCV_PCREL_LO12_I other_function+4 0000000000000008 other_function: 8: 67 80 00 00 ret The reason seems to be that in RISCVAsmBackend::shouldForceRelocation we only consider the fragment but in RISCVMCExpr::evaluatePCRelLo we consider the section. This usually works but there are cases where the section may still be the same but the fragment may be another one. In that case we end forcing a %pcrel_lo relocation without any %pcrel_hi. This patch makes RISCVAsmBackend::shouldForceRelocation use the section, if any, to determine if the relocation must be forced or not. Differential Revision: https://reviews.llvm.org/D60657 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356330: Merge commit da7b129b1 from llvm git (by James Clarke): [RISCV] Don't force Local Exec TLS for non-PIC Summary: Forcing Local Exec TLS requires the use of copy relocations. Copy relocations need special handling in the runtime linker when being used against TLS symbols, which is present in glibc, but not in FreeBSD nor musl, and so cannot be relied upon. Moreover, copy relocations are a hack that embed the size of an object in the ABI when it otherwise wouldn't be, and break protected symbols (which are expected to be DSO local), whilst also wasting space, thus they should be avoided whenever possible. As discussed in D70398, RISC-V should move away from forcing Local Exec, and instead use Initial Exec like other targets, with possible linker relaxation to follow. The RISC-V GCC maintainers also intend to adopt this more-conventional behaviour (see riscv-non-isa/riscv-elf-psabi-doc#122). Reviewers: asb, MaskRay Reviewed By: MaskRay Subscribers: emaste, krytarowski, hiraditya, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, llvm-commits, bsdjhb Tags: #llvm Differential Revision: https://reviews.llvm.org/D70649 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356331: ?Merge commit c6b09bff5 from llvm git (by Lu?s Marques): [RISCV] Fix wrong CFI directives Summary: Removes CFI CFA directives that could incorrectly propagate beyond the basic block they were inteded for. Specifically it removes the epilogue CFI directives. See the branch_and_tail_call test for an example of the issue. Should fix the stack unwinding issues caused by the incorrect directives. Reviewers: asb, lenary, shiva0217 Reviewed By: lenary Tags: #llvm Differential Revision: https://reviews.llvm.org/D69723 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356332: ?Merge commit d7be3eab5 from llvm git (by Lu?s Marques): [RISCV] Handle fcopysign(f32, f64) and fcopysign(f64, f32) Summary: Adds tablegen patterns to explicitly handle fcopysign where the magnitude and sign arguments have different types, due to the sign value casts being removed the by DAGCombiner. Support for RV32IF follows in a separate commit. Adds tests for all relevant scenarios except RV32IF. Reviewers: lenary Reviewed By: lenary Tags: #llvm Differential Revision: https://reviews.llvm.org/D70678 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356333: ?Merge commit 189b7393d from llvm git (by John Baldwin): [lld][RISCV] Use an e_flags of 0 if there are only binary input files. Summary: If none of the input files are ELF object files (for example, when generating an object file from a single binary input file via "-b binary"), use a fallback value for the ELF header flags instead of crashing with an assertion failure. Reviewers: MaskRay, ruiu, espindola Reviewed By: MaskRay, ruiu Subscribers: kevans, grimar, emaste, arichardson, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, llvm-commits, jrtc27 Tags: #llvm Differential Revision: https://reviews.llvm.org/D71101 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356701: Merge commit f46ba4f07 from llvm git (by Simon Atanasyan): [mips] Use less registers to load address of TargetExternalSymbol There is no pattern matched `add hi, (MipsLo texternalsym)`. As a result, loading an address of 32-bit symbol requires two registers and one more additional instruction: ``` addiu $1, $zero, %lo(foo) lui $2, %hi(foo) addu $25, $2, $1 ``` This patch adds the missed pattern and enables generation more effective set of instructions: ``` lui $1, %hi(foo) addiu $25, $1, %lo(foo) ``` Differential Revision: https://reviews.llvm.org/D66771 llvm-svn: 370196 Merge commit 59bb3609f from llvm git (by Simon Atanasyan): [mips] Fix 64-bit address loading in case of applying 32-bit mask to the result If result of 64-bit address loading combines with 32-bit mask, LLVM tries to optimize the code and remove "redundant" loading of upper 32-bits of the address. It leads to incorrect code on MIPS64 targets. MIPS backend creates the following chain of commands to load 64-bit address in the `MipsTargetLowering::getAddrNonPICSym64` method: ``` (add (shl (add (shl (add %highest(sym), %higher(sym)), 16), %hi(sym)), 16), %lo(%sym)) ``` If the mask presents, LLVM decides to optimize the chain of commands. It really does not make sense to load upper 32-bits because the 0x0fffffff mask anyway clears them. After removing redundant commands we get this chain: ``` (add (shl (%hi(sym), 16), %lo(%sym)) ``` There is no patterns matched `(MipsHi (i64 symbol))`. Due a bug in `SYM_32` predicate definition, backend incorrectly selects a pattern for a 32-bit symbols and uses the `lui` instruction for loading `%hi(sym)`. As a result we get incorrect set of instructions with unnecessary 16-bit left shifting: ``` lui at,0x0 R_MIPS_HI16 foo dsll at,at,0x10 daddiu at,at,0 R_MIPS_LO16 foo ``` This patch resolves two problems: - Fix `SYM_32/SYM_64` predicates to prevent selection of patterns dedicated to 32-bit symbols in case of using N64 ABI. - Add missed patterns for 64-bit symbols for `%hi/%lo`. Fix PR42736. Differential Revision: https://reviews.llvm.org/D66228 llvm-svn: 370268 These two commits fix a miscompilation of the kernel for mips64, and should allow clang to be used as the default compiler for mips64. Requested by: arichards MFC r356789 (by arichardson): Merge commit 894f742acb from llvm git (by me): [MIPS][ELF] Use PC-relative relocations in .eh_frame when possible When compiling position-independent executables, we now use DW_EH_PE_pcrel | DW_EH_PE_sdata4. However, the MIPS ABI does not define a 64-bit PC-relative ELF relocation so we cannot use sdata8 for the large code model case. When using the large code model, we fall back to the previous behaviour of generating absolute relocations. With this change clang-generated .o files can be linked by LLD without having to pass -Wl,-z,notext (which creates text relocations). This is simpler than the approach used by ld.bfd, which rewrites the .eh_frame section to convert absolute relocations into relative references. I saw in D13104 that apparently ld.bfd did not accept pc-relative relocations for MIPS ouput at some point. However, I also checked that recent ld.bfd can process the clang-generated .o files so this no longer seems true. Reviewed By: atanasyan Differential Revision: https://reviews.llvm.org/D72228 Merge commit 8e8ccf47 from llvm git (by me) [MIPS] Don't emit R_(MICRO)MIPS_JALR relocations against data symbols The R_(MICRO)MIPS_JALR optimization only works when used against functions. Using the relocation against a data symbol (e.g. function pointer) will cause some linkers that don't ignore the hint in this case (e.g. LLD prior to commit 5bab291) to generate a relative branch to the data symbol which crashes at run time. Before this patch, LLVM was erroneously emitting these relocations against local-dynamic TLS function pointers and global function pointers with internal visibility. Reviewers: atanasyan, jrtc27, vstefanovic Reviewed By: atanasyan Differential Revision: https://reviews.llvm.org/D72571 These two changes should allow using lld for MIPS64 (and maybe also MIPS32) by default. The second commit is not strictly necessary for clang+lld since LLD9 will not perform the R_MIPS_JALR optimization (it was only added for 10) but it is probably required in order to use recent ld.bfd. Reviewed By: dim, emaste Differential Revision: https://reviews.freebsd.org/D23203 MFC r356929: Merge commit bc4bc5aa0 from llvm git (by Justin Hibbits): Add 8548 CPU definition and attributes 8548 CPU is GCC's name for the e500v2, so accept this in clang. The e500v2 doesn't support lwsync, so define __NO_LWSYNC__ for this as well, as GCC does. Differential Revision: https://reviews.llvm.org/D67787 Merge commit ff0311c4b from llvm git (by Justin Hibbits): [PowerPC]: Add powerpcspe target triple subarch component Summary: This allows the use of '-target powerpcspe-unknown-linux-gnu' or 'powerpcspe-unknown-freebsd' to be used, instead of '-target powerpc-unknown-linux-gnu -mspe'. Reviewed By: dim Differential Revision: https://reviews.llvm.org/D72014 Merge commit ba91dffaf from llvm git (by Fangrui Song): [Driver][PowerPC] Move powerpcspe logic from cc1 to Driver Follow-up of D72014. It is more appropriate to use a target feature instead of a SubTypeArch to express the difference. Reviewed By: #powerpc, jhibbits Differential Revision: https://reviews.llvm.org/D72433 commit 36eedfcb3 from llvm git (by Justin Hibbits): [PowerPC] Fix powerpcspe subtarget enablement in llvm backend Summary: As currently written, -target powerpcspe will enable SPE regardless of disabling the feature later on in the command line. Instead, change this to just set a default CPU to 'e500' instead of a generic CPU. As part of this, add FeatureSPE to the e500 definition. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D72673 These are needed to unbreak the build for powerpcspe. Requested by: jhibbits MFC r358711: Merge commit f75939599 from llvm git (by Erich Keane): Reland r374450 with Richard Smith's comments and test fixed. The behavior from the original patch has changed, since we're no longer allowing LLVM to just ignore the alignment. Instead, we're just assuming the maximum possible alignment. Differential Revision: https://reviews.llvm.org/D68824 llvm-svn: 374562 This fixes 'Assertion failed: (Alignment != 0 && "Invalid Alignment"), function CreateAlignmentAssumption', when building recent versions of v8, which invoke __builtin_assume_aligned() with its alignment argument set to 4GiB or more. Clang will now report a warning, and show the maximum possible alignment instead, e.g.: huge-align.cpp:1:27: warning: requested alignment must be 536870912 bytes or smaller; maximum alignment assumed [-Wbuiltin-assume-aligned-alignment] void *f(void *g) { return __builtin_assume_aligned(g, 4294967296); } ^ ~~~~~~~~~~ Upstream PR: https://bugs.llvm.org/show_bug.cgi?id=43839 Reported by: cem
9.0.1 final release c1a0a213378a458fbea1a5c77b315c7dce08fd05, and a number of follow-ups. MFC r355948: Bootstrap mergeinfo for contrib/llvm-project Merge (record-only) the following paths to contrib/llvm-project: * ^/vendor/llvm-project/master * ^/vendor/llvm-project/release-8.x * ^/vendor/llvm-project/release-9.x MFC r355951: Merge empty dir updates from r355950 in vendor/llvm-project. MFC r355957: Merge diff elimination updates from r355953 into vendor/llvm-project. MFC r355959: Consolidate FREEBSD-Xlist files of different llvm sub-projects into one. MFC r356004: Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp 9.0.1 final release c1a0a213378a458fbea1a5c77b315c7dce08fd05. Release notes for llvm, clang, lld and libc++ 9.0.1 will become available here: https://releases.llvm.org/9.0.1/docs/ReleaseNotes.html https://releases.llvm.org/9.0.1/tools/clang/docs/ReleaseNotes.html https://releases.llvm.org/9.0.1/tools/lld/docs/ReleaseNotes.html https://releases.llvm.org/9.0.1/projects/libcxx/docs/ReleaseNotes.html PR: 240629 MFC r356005: Merge commit f97936fab from llvm git (by Eric Fiselier): [libc++] Cleanup and enable multiple warnings. Too many warnings are being disabled too quickly. Warnings are important to keeping libc++ correct. This patch re-enables two warnings: -Wconstant-evaluated and -Wdeprecated-copy. In future, all warnings disabled for the test suite should require an attached bug. The bug should state the plan for re-enabling that warning, or a strong case why it should remain disabled. This should fix a number of new g++ 9 warnings. Requested by: rlibby MFC r356100: Merge commit d3aeac8e2 from llvm git (by Justin Hibbits) [PowerPC] Only use PLT annotations if using PIC relocation model Summary: The default static (non-PIC, non-PIE) model for 32-bit powerpc does not use @plt annotations and relocations in GCC. LLVM shouldn't use @plt annotations either, because it breaks secure-PLT linking with (some versions of?) GNU LD. Update the available-externally.ll test to reflect that default mode should be the same as the static relocation, by using the same check prefix. Reviewed by: sfertile Differential Revision: https://reviews.llvm.org/D70570 Reviewed by: jhibbits Differential Revision: https://reviews.freebsd.org/D22913 MFC r356104 (by jhibbits): [PowerPC] enable atomic.c in compiler_rt and do not check and forces lock/lock_free decisions in compiled time Summary: Enables atomic.c in compiler_rt and forces clang to not emit a call for runtime decision about lock/lock_free. At compiling time, if clang can't decide if atomic operation can be lock free, it emits calls to external functions like `__atomic_is_lock_free`, `__c11_atomic_is_lock_free` and `__atomic_always_lock_free`, postponing decision to a runtime check. According to LLVM code documentation, the mechanism exists due to differences between x86_64 processors that can't be decided at runtime. On PowerPC and PowerPCSPE (32 bits), we already know in advance it can't be lock free, so we force the decision at compile time and avoid having to implement it in an external library. This patch was made after 32 bit users testing the PowePC32 bit ISO reported llvm could not be compiled with in-base llvm due to `__atomic_load8` not implemented. Submitted by: alfredo.junior_eldorado.org.br Reviewed by: jhibbits, dim Differential Revision: https://reviews.freebsd.org/D22549 MFC r356112 (by jhibbits): [PowerPC64] Starting from FreeBSD 13.0, default to ELFv2 ABI This changes the LLVM default powerpc64 ABI to ELFv2, if target OS is FreeBSD >= 13.0 This will also be sent upstream. Submitted by: alfredo.junior_eldorado.org.br Reviewed by: dim, luporl Relnotes: YES Differential Revision: https://reviews.freebsd.org/D20383 MFC r356256: Merge commit 468a0cb5f from llvm git (by Craig Topper): [X86] Add X87 FCMOV support to X86FlagsCopyLowering. Fixes PR44396 Merge commit 86f48999f from llvm git (by Craig Topper): [X86] Fix typo in getCMovOpcode. The 64-bit HasMemoryOperand line was using CMOV32rm instead of CMOV64rm. Not sure how to test this. We have no test coverage that passes true for HasMemoryOperand. This fixes 'Assertion failed: (MI.findRegisterDefOperand(X86::EFLAGS) && "Expected a def of EFLAGS for this instruction!"), function runOnMachineFunction' when compiling the misc/gpsim port for i386. Reported by: yuri Upstream PR: https://bugs.llvm.org/show_bug.cgi?id=44396 MFC r356329: Merge commit 41449c58c from llvm git (by Roger Ferrer Ibanez): [RISCV] Fix evaluation of %pcrel_lo The following testcase function: .Lpcrel_label1: auipc a0, %pcrel_hi(other_function) addi a1, a0, %pcrel_lo(.Lpcrel_label1) .p2align 2 # Causes a new fragment to be emitted .type other_function,@function other_function: ret exposes an odd behaviour in which only the %pcrel_hi relocation is evaluated but not the %pcrel_lo. $ llvm-mc -triple riscv64 -filetype obj t.s | llvm-objdump -d -r - <stdin>: file format ELF64-riscv Disassembly of section .text: 0000000000000000 function: 0: 17 05 00 00 auipc a0, 0 4: 93 05 05 00 mv a1, a0 0000000000000004: R_RISCV_PCREL_LO12_I other_function+4 0000000000000008 other_function: 8: 67 80 00 00 ret The reason seems to be that in RISCVAsmBackend::shouldForceRelocation we only consider the fragment but in RISCVMCExpr::evaluatePCRelLo we consider the section. This usually works but there are cases where the section may still be the same but the fragment may be another one. In that case we end forcing a %pcrel_lo relocation without any %pcrel_hi. This patch makes RISCVAsmBackend::shouldForceRelocation use the section, if any, to determine if the relocation must be forced or not. Differential Revision: https://reviews.llvm.org/D60657 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356330: Merge commit da7b129b1 from llvm git (by James Clarke): [RISCV] Don't force Local Exec TLS for non-PIC Summary: Forcing Local Exec TLS requires the use of copy relocations. Copy relocations need special handling in the runtime linker when being used against TLS symbols, which is present in glibc, but not in FreeBSD nor musl, and so cannot be relied upon. Moreover, copy relocations are a hack that embed the size of an object in the ABI when it otherwise wouldn't be, and break protected symbols (which are expected to be DSO local), whilst also wasting space, thus they should be avoided whenever possible. As discussed in D70398, RISC-V should move away from forcing Local Exec, and instead use Initial Exec like other targets, with possible linker relaxation to follow. The RISC-V GCC maintainers also intend to adopt this more-conventional behaviour (see riscv-non-isa/riscv-elf-psabi-doc#122). Reviewers: asb, MaskRay Reviewed By: MaskRay Subscribers: emaste, krytarowski, hiraditya, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, llvm-commits, bsdjhb Tags: #llvm Differential Revision: https://reviews.llvm.org/D70649 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356331: ?Merge commit c6b09bff5 from llvm git (by Lu?s Marques): [RISCV] Fix wrong CFI directives Summary: Removes CFI CFA directives that could incorrectly propagate beyond the basic block they were inteded for. Specifically it removes the epilogue CFI directives. See the branch_and_tail_call test for an example of the issue. Should fix the stack unwinding issues caused by the incorrect directives. Reviewers: asb, lenary, shiva0217 Reviewed By: lenary Tags: #llvm Differential Revision: https://reviews.llvm.org/D69723 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356332: ?Merge commit d7be3eab5 from llvm git (by Lu?s Marques): [RISCV] Handle fcopysign(f32, f64) and fcopysign(f64, f32) Summary: Adds tablegen patterns to explicitly handle fcopysign where the magnitude and sign arguments have different types, due to the sign value casts being removed the by DAGCombiner. Support for RV32IF follows in a separate commit. Adds tests for all relevant scenarios except RV32IF. Reviewers: lenary Reviewed By: lenary Tags: #llvm Differential Revision: https://reviews.llvm.org/D70678 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356333: ?Merge commit 189b7393d from llvm git (by John Baldwin): [lld][RISCV] Use an e_flags of 0 if there are only binary input files. Summary: If none of the input files are ELF object files (for example, when generating an object file from a single binary input file via "-b binary"), use a fallback value for the ELF header flags instead of crashing with an assertion failure. Reviewers: MaskRay, ruiu, espindola Reviewed By: MaskRay, ruiu Subscribers: kevans, grimar, emaste, arichardson, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, llvm-commits, jrtc27 Tags: #llvm Differential Revision: https://reviews.llvm.org/D71101 This is a prerequisite for building and linking hard- and soft-float riscv worlds with clang and lld. Requested by: jhb MFC r356701: Merge commit f46ba4f07 from llvm git (by Simon Atanasyan): [mips] Use less registers to load address of TargetExternalSymbol There is no pattern matched `add hi, (MipsLo texternalsym)`. As a result, loading an address of 32-bit symbol requires two registers and one more additional instruction: ``` addiu $1, $zero, %lo(foo) lui $2, %hi(foo) addu $25, $2, $1 ``` This patch adds the missed pattern and enables generation more effective set of instructions: ``` lui $1, %hi(foo) addiu $25, $1, %lo(foo) ``` Differential Revision: https://reviews.llvm.org/D66771 llvm-svn: 370196 Merge commit 59bb3609f from llvm git (by Simon Atanasyan): [mips] Fix 64-bit address loading in case of applying 32-bit mask to the result If result of 64-bit address loading combines with 32-bit mask, LLVM tries to optimize the code and remove "redundant" loading of upper 32-bits of the address. It leads to incorrect code on MIPS64 targets. MIPS backend creates the following chain of commands to load 64-bit address in the `MipsTargetLowering::getAddrNonPICSym64` method: ``` (add (shl (add (shl (add %highest(sym), %higher(sym)), 16), %hi(sym)), 16), %lo(%sym)) ``` If the mask presents, LLVM decides to optimize the chain of commands. It really does not make sense to load upper 32-bits because the 0x0fffffff mask anyway clears them. After removing redundant commands we get this chain: ``` (add (shl (%hi(sym), 16), %lo(%sym)) ``` There is no patterns matched `(MipsHi (i64 symbol))`. Due a bug in `SYM_32` predicate definition, backend incorrectly selects a pattern for a 32-bit symbols and uses the `lui` instruction for loading `%hi(sym)`. As a result we get incorrect set of instructions with unnecessary 16-bit left shifting: ``` lui at,0x0 R_MIPS_HI16 foo dsll at,at,0x10 daddiu at,at,0 R_MIPS_LO16 foo ``` This patch resolves two problems: - Fix `SYM_32/SYM_64` predicates to prevent selection of patterns dedicated to 32-bit symbols in case of using N64 ABI. - Add missed patterns for 64-bit symbols for `%hi/%lo`. Fix PR42736. Differential Revision: https://reviews.llvm.org/D66228 llvm-svn: 370268 These two commits fix a miscompilation of the kernel for mips64, and should allow clang to be used as the default compiler for mips64. Requested by: arichards MFC r356789 (by arichardson): Merge commit 894f742acb from llvm git (by me): [MIPS][ELF] Use PC-relative relocations in .eh_frame when possible When compiling position-independent executables, we now use DW_EH_PE_pcrel | DW_EH_PE_sdata4. However, the MIPS ABI does not define a 64-bit PC-relative ELF relocation so we cannot use sdata8 for the large code model case. When using the large code model, we fall back to the previous behaviour of generating absolute relocations. With this change clang-generated .o files can be linked by LLD without having to pass -Wl,-z,notext (which creates text relocations). This is simpler than the approach used by ld.bfd, which rewrites the .eh_frame section to convert absolute relocations into relative references. I saw in D13104 that apparently ld.bfd did not accept pc-relative relocations for MIPS ouput at some point. However, I also checked that recent ld.bfd can process the clang-generated .o files so this no longer seems true. Reviewed By: atanasyan Differential Revision: https://reviews.llvm.org/D72228 Merge commit 8e8ccf47 from llvm git (by me) [MIPS] Don't emit R_(MICRO)MIPS_JALR relocations against data symbols The R_(MICRO)MIPS_JALR optimization only works when used against functions. Using the relocation against a data symbol (e.g. function pointer) will cause some linkers that don't ignore the hint in this case (e.g. LLD prior to commit 5bab291) to generate a relative branch to the data symbol which crashes at run time. Before this patch, LLVM was erroneously emitting these relocations against local-dynamic TLS function pointers and global function pointers with internal visibility. Reviewers: atanasyan, jrtc27, vstefanovic Reviewed By: atanasyan Differential Revision: https://reviews.llvm.org/D72571 These two changes should allow using lld for MIPS64 (and maybe also MIPS32) by default. The second commit is not strictly necessary for clang+lld since LLD9 will not perform the R_MIPS_JALR optimization (it was only added for 10) but it is probably required in order to use recent ld.bfd. Reviewed By: dim, emaste Differential Revision: https://reviews.freebsd.org/D23203 MFC r356929: Merge commit bc4bc5aa0 from llvm git (by Justin Hibbits): Add 8548 CPU definition and attributes 8548 CPU is GCC's name for the e500v2, so accept this in clang. The e500v2 doesn't support lwsync, so define __NO_LWSYNC__ for this as well, as GCC does. Differential Revision: https://reviews.llvm.org/D67787 Merge commit ff0311c4b from llvm git (by Justin Hibbits): [PowerPC]: Add powerpcspe target triple subarch component Summary: This allows the use of '-target powerpcspe-unknown-linux-gnu' or 'powerpcspe-unknown-freebsd' to be used, instead of '-target powerpc-unknown-linux-gnu -mspe'. Reviewed By: dim Differential Revision: https://reviews.llvm.org/D72014 Merge commit ba91dffaf from llvm git (by Fangrui Song): [Driver][PowerPC] Move powerpcspe logic from cc1 to Driver Follow-up of D72014. It is more appropriate to use a target feature instead of a SubTypeArch to express the difference. Reviewed By: #powerpc, jhibbits Differential Revision: https://reviews.llvm.org/D72433 commit 36eedfcb3 from llvm git (by Justin Hibbits): [PowerPC] Fix powerpcspe subtarget enablement in llvm backend Summary: As currently written, -target powerpcspe will enable SPE regardless of disabling the feature later on in the command line. Instead, change this to just set a default CPU to 'e500' instead of a generic CPU. As part of this, add FeatureSPE to the e500 definition. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D72673 These are needed to unbreak the build for powerpcspe. Requested by: jhibbits MFC r358711: Merge commit f75939599 from llvm git (by Erich Keane): Reland r374450 with Richard Smith's comments and test fixed. The behavior from the original patch has changed, since we're no longer allowing LLVM to just ignore the alignment. Instead, we're just assuming the maximum possible alignment. Differential Revision: https://reviews.llvm.org/D68824 llvm-svn: 374562 This fixes 'Assertion failed: (Alignment != 0 && "Invalid Alignment"), function CreateAlignmentAssumption', when building recent versions of v8, which invoke __builtin_assume_aligned() with its alignment argument set to 4GiB or more. Clang will now report a warning, and show the maximum possible alignment instead, e.g.: huge-align.cpp:1:27: warning: requested alignment must be 536870912 bytes or smaller; maximum alignment assumed [-Wbuiltin-assume-aligned-alignment] void *f(void *g) { return __builtin_assume_aligned(g, 4294967296); } ^ ~~~~~~~~~~ Upstream PR: https://bugs.llvm.org/show_bug.cgi?id=43839 Reported by: cem git-svn-id: https://svn.freebsd.org/base/stable/11@360661 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
#94 tracks TLSDESC (replacement for traditional General Dynamic and Local Dynamic), while this issue tracks Initial Exec to Local Exec relaxation.
For external TLS variable accesses,
Currently gcc (clang is similar) emits:
Emitting Local Exec code sequences in the position dependent (-fno-pic) code is really bad (it makes st_size and st_align part of the ABI. TLS copy relocation needs cooperation from the dynamic loader. According to Rich Felker, R_RISCV_COPY does not work on musl. I think the relevant source is
ldso/dynlink.c
case REL_COPY:
. FreeBSD rtld (libexec/rtld-elf/riscv/reloc.c
) do not seem to support it, either. glibc (sysdeps/riscv/dl-machine.h
) supports it.Fixed
st_size
in the executable means extended array lengths in the shared object does not work.). If we apply riscvarchive/riscv-gcc#118 , we will make the -fno-pic output consistent with the-fpie
output.For both -fno-pic and -fpie, there will be some overhead if the variable
var
turns out to be defined in the executable. Defining Initial Exec to Local Exec relaxation can eliminate the cost.The text was updated successfully, but these errors were encountered: