diff --git a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp --- a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp +++ b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp @@ -328,13 +328,15 @@ std::pair ModuleSanitizerCoverage::CreateSecStartEnd(Module &M, const char *Section, Type *Ty) { + // Use ExternalWeak so that if all sections are discarded due to section + // garbage collection, the linker will not report undefined symbol errors. GlobalVariable *SecStart = new GlobalVariable( - M, Ty->getPointerElementType(), false, GlobalVariable::ExternalLinkage, - nullptr, getSectionStart(Section)); + M, Ty->getPointerElementType(), false, + GlobalVariable::ExternalWeakLinkage, nullptr, getSectionStart(Section)); SecStart->setVisibility(GlobalValue::HiddenVisibility); GlobalVariable *SecEnd = new GlobalVariable( - M, Ty->getPointerElementType(), false, GlobalVariable::ExternalLinkage, - nullptr, getSectionEnd(Section)); + M, Ty->getPointerElementType(), false, + GlobalVariable::ExternalWeakLinkage, nullptr, getSectionEnd(Section)); SecEnd->setVisibility(GlobalValue::HiddenVisibility); IRBuilder<> IRB(M.getContext()); if (!TargetTriple.isOSBinFormatCOFF()) diff --git a/llvm/test/Instrumentation/SanitizerCoverage/inline-8bit-counters.ll b/llvm/test/Instrumentation/SanitizerCoverage/inline-8bit-counters.ll --- a/llvm/test/Instrumentation/SanitizerCoverage/inline-8bit-counters.ll +++ b/llvm/test/Instrumentation/SanitizerCoverage/inline-8bit-counters.ll @@ -2,11 +2,14 @@ ; RUN: opt < %s -sancov -sanitizer-coverage-level=1 -sanitizer-coverage-inline-8bit-counters=1 -S -enable-new-pm=0 | FileCheck %s ; RUN: opt < %s -passes='module(sancov-module)' -sanitizer-coverage-level=1 -sanitizer-coverage-inline-8bit-counters=1 -S | FileCheck %s +; CHECK: @__sancov_gen_ = private global [1 x i8] zeroinitializer, section "__sancov_cntrs", comdat($foo), align 1 +; CHECK: @__start___sancov_cntrs = extern_weak hidden global i8 +; CHECK-NEXT: @__stop___sancov_cntrs = extern_weak hidden global i8 + target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64" target triple = "x86_64-unknown-linux-gnu" define void @foo() { entry: -; CHECK: section "__sancov_cntrs", comdat($foo), align 1 ; CHECK: %0 = load i8, i8* getelementptr inbounds ([1 x i8], [1 x i8]* @__sancov_gen_, i64 0, i64 0), align 1, !nosanitize ; CHECK: %1 = add i8 %0, 1 ; CHECK: store i8 %1, i8* getelementptr inbounds ([1 x i8], [1 x i8]* @__sancov_gen_, i64 0, i64 0), align 1, !nosanitize diff --git a/llvm/test/Instrumentation/SanitizerCoverage/inline-bool-flag.ll b/llvm/test/Instrumentation/SanitizerCoverage/inline-bool-flag.ll --- a/llvm/test/Instrumentation/SanitizerCoverage/inline-bool-flag.ll +++ b/llvm/test/Instrumentation/SanitizerCoverage/inline-bool-flag.ll @@ -4,6 +4,8 @@ ; CHECK: $foo = comdat noduplicates ; CHECK: @__sancov_gen_ = private global [1 x i1] zeroinitializer, section "__sancov_bools", comdat($foo), align 1{{$}} +; CHECK: @__start___sancov_bools = extern_weak hidden global i1 +; CHECK-NEXT: @__stop___sancov_bools = extern_weak hidden global i1 ; CHECK-NOT: @llvm.used = ; CHECK: @llvm.compiler.used = appending global [1 x i8*] [i8* bitcast ([1 x i1]* @__sancov_gen_ to i8*)], section "llvm.metadata" diff --git a/llvm/test/Instrumentation/SanitizerCoverage/pc-table.ll b/llvm/test/Instrumentation/SanitizerCoverage/pc-table.ll --- a/llvm/test/Instrumentation/SanitizerCoverage/pc-table.ll +++ b/llvm/test/Instrumentation/SanitizerCoverage/pc-table.ll @@ -22,6 +22,8 @@ } ; CHECK: private constant [6 x i64*] [{{.*}}@foo{{.*}}blockaddress{{.*}}blockaddress{{.*}}], section "__sancov_pcs", comdat($foo), align 8 +; CHECK: @__start___sancov_pcs = extern_weak hidden global i64 +; CHECK-NEXT: @__stop___sancov_pcs = extern_weak hidden global i64 ; CHECK: define internal void @sancov.module_ctor ; CHECK: call void @__sanitizer_cov ; CHECK: call void @__sanitizer_cov_pcs_init