https://github.com/nikic created https://github.com/llvm/llvm-project/pull/230064
MergeFunctions::mergeTwoFunctions may turn identical functions into a private unnamed function, which trips `assert(F.hasName())`. Without assertions, all unnamed functions share an empty-name IR comdat (which yields no ELF section group per MCContext::getELFSection). Fix #228820: Just drop comdat for unnamed functions. SanitizerCoverage then retains the metadata sections via `llvm.used`. It's acceptable to have redundat metadata sections with discarded associated text sections. (cherry picked from commit 09b7f9faf6170f6deb7c185cc6219d5741edcba8) ----- Manual cherry-pick to resolve conflict with noipa changes. I've dropped the comment-only changes from SanitizerCoverage as part of that. >From 14dd1560b3e4107bed7719a637bd325e02c65549 Mon Sep 17 00:00:00 2001 From: Fangrui Song <[email protected]> Date: Mon, 5 Oct 2026 18:58:35 -0700 Subject: [PATCH] [SanitizerCoverage] Don't create comdat for unnamed functions (#228959) MergeFunctions::mergeTwoFunctions may turn identical functions into a private unnamed function, which trips `assert(F.hasName())`. Without assertions, all unnamed functions share an empty-name IR comdat (which yields no ELF section group per MCContext::getELFSection). Fix #228820: Just drop comdat for unnamed functions. SanitizerCoverage then retains the metadata sections via `llvm.used`. It's acceptable to have redundat metadata sections with discarded associated text sections. (cherry picked from commit 09b7f9faf6170f6deb7c185cc6219d5741edcba8) --- llvm/lib/Transforms/Utils/Instrumentation.cpp | 5 +++- .../SanitizerCoverage/interposable-symbol.ll | 25 ++++++++++++++----- 2 files changed, 23 insertions(+), 7 deletions(-) diff --git a/llvm/lib/Transforms/Utils/Instrumentation.cpp b/llvm/lib/Transforms/Utils/Instrumentation.cpp index 3e43b85a11a3c..5f71703725ba1 100644 --- a/llvm/lib/Transforms/Utils/Instrumentation.cpp +++ b/llvm/lib/Transforms/Utils/Instrumentation.cpp @@ -96,7 +96,10 @@ GlobalVariable *llvm::createPrivateGlobalForString(Module &M, StringRef Str, Comdat *llvm::getOrCreateFunctionComdat(Function &F, Triple &T) { if (auto Comdat = F.getComdat()) return Comdat; - assert(F.hasName()); + // Unnamed functions would share a single empty-name comdat, which has little + // linker garbage collection benefit. + if (!F.hasName()) + return nullptr; Module *M = F.getParent(); // Make a new comdat for the function. Use the "no duplicates" selection kind diff --git a/llvm/test/Instrumentation/SanitizerCoverage/interposable-symbol.ll b/llvm/test/Instrumentation/SanitizerCoverage/interposable-symbol.ll index e8b23096ff33a..5143dfd0a54ae 100644 --- a/llvm/test/Instrumentation/SanitizerCoverage/interposable-symbol.ll +++ b/llvm/test/Instrumentation/SanitizerCoverage/interposable-symbol.ll @@ -6,6 +6,8 @@ $WeakComdat = comdat any define void @Vanilla() { entry: + call i32 @0() + call i32 @1() ret void } @@ -36,17 +38,28 @@ entry: ret void } +define private i32 @0() { + ret i32 0 +} + +define i32 @1() { + ret i32 1 +} ; CHECK: $Vanilla = comdat nodeduplicate ; ELF: $LinkOnceOdr = comdat nodeduplicate ; COFF: $LinkOnceOdr = comdat any ; CHECK: $WeakComdat = comdat any -; CHECK: @__sancov_gen_ = private global [1 x i32] zeroinitializer, section {{.*}}, comdat($Vanilla), align 4{{$}} -; CHECK-NEXT: @__sancov_gen_.1 = private global [1 x i32] zeroinitializer, section {{.*}}, align 4{{$}} -; CHECK-NEXT: @__sancov_gen_.2 = private global [1 x i32] zeroinitializer, section {{.*}}, align 4{{$}} -; CHECK-NEXT: @__sancov_gen_.3 = private global [1 x i32] zeroinitializer, section {{.*}}, comdat($LinkOnceOdr), align 4{{$}} -; CHECK-NEXT: @__sancov_gen_.4 = private global [1 x i32] zeroinitializer, section {{.*}}, comdat($WeakOdr), align 4{{$}} -; CHECK-NEXT: @__sancov_gen_.5 = private global [1 x i32] zeroinitializer, section {{.*}}, comdat($WeakComdat), align 4{{$}} +; CHECK: @__sancov_gen_ = private global [1 x i32] zeroinitializer, section "{{[^"]*}}", comdat($Vanilla), align 4{{$}} +; ELF-NEXT: @__sancov_gen_.1 = private global [1 x i32] zeroinitializer, section "{{[^"]*}}", comdat($LinkOnce), align 4{{$}} +; ELF-NEXT: @__sancov_gen_.2 = private global [1 x i32] zeroinitializer, section "{{[^"]*}}", comdat($Weak), align 4{{$}} +; COFF-NEXT: @__sancov_gen_.1 = private global [1 x i32] zeroinitializer, section "{{[^"]*}}", align 4{{$}} +; COFF-NEXT: @__sancov_gen_.2 = private global [1 x i32] zeroinitializer, section "{{[^"]*}}", align 4{{$}} +; CHECK-NEXT: @__sancov_gen_.3 = private global [1 x i32] zeroinitializer, section "{{[^"]*}}", comdat($LinkOnceOdr), align 4{{$}} +; CHECK-NEXT: @__sancov_gen_.4 = private global [1 x i32] zeroinitializer, section "{{[^"]*}}", comdat($WeakOdr), align 4{{$}} +; CHECK-NEXT: @__sancov_gen_.5 = private global [1 x i32] zeroinitializer, section "{{[^"]*}}", comdat($WeakComdat), align 4{{$}} +; CHECK-NEXT: @__sancov_gen_.6 = private global [1 x i32] zeroinitializer, section "{{[^"]*}}", align 4{{$}} +; CHECK-NEXT: @__sancov_gen_.7 = private global [1 x i32] zeroinitializer, section "{{[^"]*}}", align 4{{$}} ; CHECK: define void @Vanilla() comdat { ; ELF: define linkonce void @LinkOnce() comdat { _______________________________________________ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
