Author: James Clarke Date: 2020-01-24T19:10:45+01:00 New Revision: a3db4e05e36e836077e6e551feb6841c7e8023a0
URL: https://github.com/llvm/llvm-project/commit/a3db4e05e36e836077e6e551feb6841c7e8023a0 DIFF: https://github.com/llvm/llvm-project/commit/a3db4e05e36e836077e6e551feb6841c7e8023a0.diff LOG: [lld][RISCV] Print error when encountering R_RISCV_ALIGN Summary: Unlike R_RISCV_RELAX, which is a linker hint, R_RISCV_ALIGN requires the support of the linker even when ignoring all R_RISCV_RELAX relocations. This is because the compiler emits as many NOPs as may be required for the requested alignment, more than may be required pre-relaxation, to allow for the target becoming more unaligned after relaxing earlier sequences. This means that the target is often not initially aligned in the object files, and so the R_RISCV_ALIGN relocations cannot just be ignored. Since we do not support linker relaxation, we must turn these into errors. Reviewers: ruiu, MaskRay, espindola Reviewed By: MaskRay Subscribers: grimar, Jim, emaste, arichardson, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D71820 (cherry picked from commit d1da63664f4e42191daf2e6a9fa682ca9f75ef5e) Added: lld/test/ELF/riscv-reloc-align.s Modified: lld/ELF/Arch/RISCV.cpp Removed: ################################################################################ diff --git a/lld/ELF/Arch/RISCV.cpp b/lld/ELF/Arch/RISCV.cpp index 42db8e08162d..527f9db0ef29 100644 --- a/lld/ELF/Arch/RISCV.cpp +++ b/lld/ELF/Arch/RISCV.cpp @@ -236,9 +236,15 @@ RelExpr RISCV::getRelExpr(const RelType type, const Symbol &s, case R_RISCV_TPREL_LO12_S: return R_TLS; case R_RISCV_RELAX: - case R_RISCV_ALIGN: case R_RISCV_TPREL_ADD: return R_NONE; + case R_RISCV_ALIGN: + // Not just a hint; always padded to the worst-case number of NOPs, so may + // not currently be aligned, and without linker relaxation support we can't + // delete NOPs to realign. + errorOrWarn(getErrorLocation(loc) + "relocation R_RISCV_ALIGN requires " + "unimplemented linker relaxation; recompile with -mno-relax"); + return R_NONE; default: error(getErrorLocation(loc) + "unknown relocation (" + Twine(type) + ") against symbol " + toString(s)); @@ -431,7 +437,6 @@ void RISCV::relocateOne(uint8_t *loc, const RelType type, write64le(loc, val - dtpOffset); break; - case R_RISCV_ALIGN: case R_RISCV_RELAX: return; // Ignored (for now) diff --git a/lld/test/ELF/riscv-reloc-align.s b/lld/test/ELF/riscv-reloc-align.s new file mode 100644 index 000000000000..5103066caa37 --- /dev/null +++ b/lld/test/ELF/riscv-reloc-align.s @@ -0,0 +1,12 @@ +# REQUIRES: riscv + +# RUN: llvm-mc -filetype=obj -triple=riscv32 -mattr=+relax %s -o %t.o +# RUN: not ld.lld %t.o -o /dev/null 2>&1 | FileCheck %s + +# CHECK: relocation R_RISCV_ALIGN requires unimplemented linker relaxation + +.global _start +_start: + nop + .balign 8 + nop _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
