From 4914c9836765532ffaec9c85bc57690dbdaeb50f Mon Sep 17 00:00:00 2001 From: Nick Desaulniers Date: Mon, 12 Apr 2021 15:55:53 -0700 Subject: [PATCH] [SantizerCoverage] handle missing DBG MD when inserting libcalls Instruction::getDebugLoc can return an invalid DebugLoc. For such cases where metadata was accidentally removed from the libcall insertion point, simply insert a DILocation with line 0 scoped to the caller. When we can inline the libcall, such as during LTO, then we won't fail a Verifier check that all calls to functions with debug metadata themselves must have debug metadata. Reviewed By: dblaikie Differential Revision: https://reviews.llvm.org/D100158 --- .../Instrumentation/SanitizerCoverage.cpp | 3 ++ .../SanitizerCoverage/crit-edge-sancov.ll | 52 ++++++++++++++++++++++ 2 files changed, 55 insertions(+) create mode 100644 llvm/test/Instrumentation/SanitizerCoverage/crit-edge-sancov.ll diff --git a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp index 166dd10..60cdecdc 100644 --- a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp +++ b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp @@ -904,6 +904,9 @@ void ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB, IP = PrepareToSplitEntryBlock(BB, IP); } else { EntryLoc = IP->getDebugLoc(); + if (!EntryLoc) + if (auto *SP = F.getSubprogram()) + EntryLoc = DILocation::get(SP->getContext(), 0, 0, SP); } IRBuilder<> IRB(&*IP); diff --git a/llvm/test/Instrumentation/SanitizerCoverage/crit-edge-sancov.ll b/llvm/test/Instrumentation/SanitizerCoverage/crit-edge-sancov.ll new file mode 100644 index 0000000..a752562 --- /dev/null +++ b/llvm/test/Instrumentation/SanitizerCoverage/crit-edge-sancov.ll @@ -0,0 +1,52 @@ +; RUN: opt -passes='module(sancov-module)' -sanitizer-coverage-trace-pc \ +; RUN: -sanitizer-coverage-level=3 %s -S -o - | FileCheck %s + +; The edge between %entry and %for.inc.i is a critical edge. +; ModuleSanitizerCoveragePass must split this critical edge in order to track +; coverage of this edge. ModuleSanitizerCoveragePass will also insert calls to +; @__sanitizer_cov_trace_pc using the debug location from the predecessor's +; branch. but, if the branch itself is missing debug info (say, by accident +; due to a bug in an earlier transform), we would fail a verifier check that +; verifies calls to functions with debug info themselves have debug info. +; The definition of @__sanitizer_cov_trace_pc may be visible during LTO. + +; Of the below checks, we really only care that the calls to +; @__sanitizer_cov_trace_pc retain !dbg metadata. + +define void @update_shadow() !dbg !3 { +; CHECK-LABEL: @update_shadow( +; CHECK-NEXT: entry: +; CHECK-NEXT: call void @__sanitizer_cov_trace_pc() #[[ATTR0:[0-9]+]], !dbg [[DBG6:![0-9]+]] +; CHECK: entry.for.inc.i_crit_edge: +; CHECK-NEXT: call void @__sanitizer_cov_trace_pc() #[[ATTR0]], !dbg [[DBG7:![0-9]+]] +; CHECK: if.end22.i: +; CHECK-NEXT: call void @__sanitizer_cov_trace_pc() #[[ATTR0]], !dbg [[DBG8:![0-9]+]] +; CHECK: [[DBG6]] = !DILocation(line: 192, scope: !3) +; CHECK: [[DBG7]] = !DILocation(line: 0, scope: !3) +; CHECK: [[DBG8]] = !DILocation(line: 129, column: 2, scope: !3) +entry: + br i1 undef, label %for.inc.i, label %if.end22.i + +if.end22.i: ; preds = %entry + br label %for.inc.i, !dbg !8 + +for.inc.i: ; preds = %if.end22.i, %entry + ret void, !dbg !6 +} + +define void @__sanitizer_cov_trace_pc() !dbg !7{ + ret void +} + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!2} + +!0 = distinct !DICompileUnit(language: DW_LANG_C89, file: !1, producer: "", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, splitDebugInlining: false, nameTableKind: None) +!1 = !DIFile(filename: "kernel/cfi.c", directory: "") +!2 = !{i32 2, !"Debug Info Version", i32 3} +!3 = distinct !DISubprogram(name: "update_shadow", scope: !1, file: !1, line: 190, type: !4, scopeLine: 192, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0) +!4 = !DISubroutineType(types: !5) +!5 = !{} +!6 = !DILocation(line: 223, column: 1, scope: !3) +!7 = distinct !DISubprogram(name: "__sanitizer_cov_trace_pc", scope: !1, file: !1, line: 200, type: !4, scopeLine: 200, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0) +!8 = !DILocation(line: 129, column: 2, scope: !3) -- 2.7.4