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[pull] master from llvm:master #512
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Summary: not every read in CXXConstructorDecl::getExplicitSpecifierInternal() was made on the canonical declaration. Reviewers: rsmith, aaron.ballman Reviewed By: rsmith Subscribers: cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D67889 llvm-svn: 372530
Extracted from D63082. GCC has this warning under -Wint-in-bool-context, but as noted in the D63082's review, we should put it under TautologicalConstantCompare. llvm-svn: 372531
…llback to BZHI is profitable (PR43381) Summary: PR43381 notes that while we are good at matching `(X >> C1) & C2` as BEXTR/BEXTRI, we only do that if we either have BEXTRI (TBM), or if BEXTR is marked as being fast (`-mattr=+fast-bextr`). In all other cases we don't match. But that is mainly only true for AMD CPU's. However, for all the CPU's for which we have sched models, the BZHI is always fast (or the sched models are all bad.) So if we decide that it's unprofitable to emit BEXTR/BEXTRI, we should consider falling-back to BZHI if it is available, and follow-up with the shift. While it's really tempting to do something because it's cool it is wise to first think whether it actually makes sense to do. We shouldn't just use BZHI because we can, but only it it is beneficial. In particular, it isn't really worth it if the input is a register, mask is small, or we can fold a load. But it is worth it if the mask does not fit into 32-bits. (careful, i don't know much about intel cpu's, my choice of `-mcpu` may be bad here) Thus we manage to fold a load: https://godbolt.org/z/Er0OQz Or if we'd end up using BZHI anyways because the mask is large: https://godbolt.org/z/dBJ_5h But this isn'r actually profitable in general case, e.g. here we'd increase microop count (the register renaming is free, mca does not model that there it seems) https://godbolt.org/z/k6wFoz Likewise, not worth it if we just get load folding: https://godbolt.org/z/1M1deG https://bugs.llvm.org/show_bug.cgi?id=43381 Reviewers: RKSimon, craig.topper, davezarzycki, spatel Reviewed By: craig.topper, davezarzycki Subscribers: andreadb, hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D67875 llvm-svn: 372532
llvm-svn: 372533
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Summary: The greedy register allocator occasionally decides to insert a large number of unnecessary copies, see below for an example. The -consider-local-interval-cost option (which X86 already enables by default) fixes this. We enable this option for AArch64 only after receiving feedback that this change is not beneficial for PowerPC. We evaluated the impact of this change on compile time, code size and performance benchmarks. This option has a small impact on compile time, measured on CTMark. A 0.1% geomean regression on -O1 and -O2, and 0.2% geomean for -O3, with at most 0.5% on individual benchmarks. The effect on both code size and performance on AArch64 for the LLVM test suite is nil on the geomean with individual outliers (ignoring short exec_times) between: best worst size..text -3.3% +0.0% exec_time -5.8% +2.3% On SPEC CPU® 2017 (compiled for AArch64) there is a minor reduction (-0.2% at most) in code size on some benchmarks, with a tiny movement (-0.01%) on the geomean. Neither intrate nor fprate show any change in performance. This patch makes the following changes. - For the AArch64 target, enableAdvancedRASplitCost() now returns true. - Ensures that -consider-local-interval-cost=false can disable the new behaviour if necessary. This matrix multiply example: $ cat test.c long A[8][8]; long B[8][8]; long C[8][8]; void run_test() { for (int k = 0; k < 8; k++) { for (int i = 0; i < 8; i++) { for (int j = 0; j < 8; j++) { C[i][j] += A[i][k] * B[k][j]; } } } } results in the following generated code on AArch64: $ clang --target=aarch64-arm-none-eabi -O3 -S test.c -o - [...] // %for.cond1.preheader // =>This Inner Loop Header: Depth=1 add x14, x11, x9 str q0, [sp, #16] // 16-byte Folded Spill ldr q0, [x14] mov v2.16b, v15.16b mov v15.16b, v14.16b mov v14.16b, v13.16b mov v13.16b, v12.16b mov v12.16b, v11.16b mov v11.16b, v10.16b mov v10.16b, v9.16b mov v9.16b, v8.16b mov v8.16b, v31.16b mov v31.16b, v30.16b mov v30.16b, v29.16b mov v29.16b, v28.16b mov v28.16b, v27.16b mov v27.16b, v26.16b mov v26.16b, v25.16b mov v25.16b, v24.16b mov v24.16b, v23.16b mov v23.16b, v22.16b mov v22.16b, v21.16b mov v21.16b, v20.16b mov v20.16b, v19.16b mov v19.16b, v18.16b mov v18.16b, v17.16b mov v17.16b, v16.16b mov v16.16b, v7.16b mov v7.16b, v6.16b mov v6.16b, v5.16b mov v5.16b, v4.16b mov v4.16b, v3.16b mov v3.16b, v1.16b mov x12, v0.d[1] fmov x15, d0 ldp q1, q0, [x14, #16] ldur x1, [x10, #-256] ldur x2, [x10, #-192] add x9, x9, #64 // =64 mov x13, v1.d[1] fmov x16, d1 ldr q1, [x14, #48] mul x3, x15, x1 mov x14, v0.d[1] fmov x17, d0 mov x18, v1.d[1] fmov x0, d1 mov v1.16b, v3.16b mov v3.16b, v4.16b mov v4.16b, v5.16b mov v5.16b, v6.16b mov v6.16b, v7.16b mov v7.16b, v16.16b mov v16.16b, v17.16b mov v17.16b, v18.16b mov v18.16b, v19.16b mov v19.16b, v20.16b mov v20.16b, v21.16b mov v21.16b, v22.16b mov v22.16b, v23.16b mov v23.16b, v24.16b mov v24.16b, v25.16b mov v25.16b, v26.16b mov v26.16b, v27.16b mov v27.16b, v28.16b mov v28.16b, v29.16b mov v29.16b, v30.16b mov v30.16b, v31.16b mov v31.16b, v8.16b mov v8.16b, v9.16b mov v9.16b, v10.16b mov v10.16b, v11.16b mov v11.16b, v12.16b mov v12.16b, v13.16b mov v13.16b, v14.16b mov v14.16b, v15.16b mov v15.16b, v2.16b ldr q2, [sp] // 16-byte Folded Reload fmov d0, x3 mul x3, x12, x1 [...] With -consider-local-interval-cost the same section of code results in the following: $ clang --target=aarch64-arm-none-eabi -mllvm -consider-local-interval-cost -O3 -S test.c -o - [...] .LBB0_1: // %for.cond1.preheader // =>This Inner Loop Header: Depth=1 add x14, x11, x9 ldp q0, q1, [x14] ldur x1, [x10, #-256] ldur x2, [x10, #-192] add x9, x9, #64 // =64 mov x12, v0.d[1] fmov x15, d0 mov x13, v1.d[1] fmov x16, d1 ldp q0, q1, [x14, #32] mul x3, x15, x1 cmp x9, #512 // =512 mov x14, v0.d[1] fmov x17, d0 fmov d0, x3 mul x3, x12, x1 [...] Reviewers: SjoerdMeijer, samparker, dmgreen, qcolombet Reviewed By: dmgreen Subscribers: ZhangKang, jsji, wuzish, ppc-slack, lkail, steven.zhang, MatzeB, qcolombet, kristof.beyls, hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D69437
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