diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVELFStreamer.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVELFStreamer.cpp index 9db5148208b3e..961b8f0afe225 100644 --- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVELFStreamer.cpp +++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVELFStreamer.cpp @@ -37,6 +37,13 @@ RISCVTargetELFStreamer::RISCVTargetELFStreamer(MCStreamer &S, auto &MAB = static_cast(MCA.getBackend()); setTargetABI(RISCVABI::computeTargetABI(STI.getTargetTriple(), Features, MAB.getTargetOptions().getABIName())); + // `j label` in `.option norelax; j label; .option relax; ...; label:` needs a + // relocation to ensure the jump target is correct after linking. This is due + // to a limitation that shouldForceRelocation has to make the decision upfront + // without knowing a possibly future .option relax. When RISCVAsmParser is used, + // its ParseInstruction may call setForceRelocs as well. + if (STI.hasFeature(RISCV::FeatureRelax)) + static_cast(MAB).setForceRelocs(); } RISCVELFStreamer &RISCVTargetELFStreamer::getStreamer() { diff --git a/llvm/test/CodeGen/RISCV/option-relax-relocation.ll b/llvm/test/CodeGen/RISCV/option-relax-relocation.ll new file mode 100644 index 0000000000000..3dc5aa64bb368 --- /dev/null +++ b/llvm/test/CodeGen/RISCV/option-relax-relocation.ll @@ -0,0 +1,31 @@ +;; With +relax, J below needs a relocation to ensure the target is correct +;; after linker relaxation. See https://github.com/ClangBuiltLinux/linux/issues/1965 + +; RUN: llc -mtriple=riscv64 -mattr=-relax -filetype=obj < %s \ +; RUN: | llvm-objdump -d -r - | FileCheck %s +; RUN: llc -mtriple=riscv64 -mattr=+relax -filetype=obj < %s \ +; RUN: | llvm-objdump -d -r - | FileCheck %s --check-prefixes=CHECK,RELAX + +; CHECK: j {{.*}} +; RELAX-NEXT: R_RISCV_JAL {{.*}} +; CHECK-NEXT: auipc ra, 0x0 +; CHECK-NEXT: R_RISCV_CALL_PLT f +; RELAX-NEXT: R_RISCV_RELAX *ABS* +; CHECK-NEXT: jalr ra + +define dso_local noundef signext i32 @main() local_unnamed_addr #0 { +entry: + callbr void asm sideeffect ".option push\0A.option norvc\0A.option norelax\0Aj $0\0A.option pop\0A", "!i"() #2 + to label %asm.fallthrough [label %label] + +asm.fallthrough: ; preds = %entry + tail call void @f() + br label %label + +label: ; preds = %asm.fallthrough, %entry + ret i32 0 +} + +declare void @f() + +attributes #0 = { nounwind "target-features"="-c,+relax" }