[llvm] a7c57c4 - tsan: don't consider debug calls as calls

[Dmitry Vyukov via llvm-commits]

Author: Dmitry Vyukov
Date: 2021-11-17T14:42:16+01:00
New Revision: a7c57c4ec8100523e200ed1f608e1efbfd43a2f6

URL: https://github.com/llvm/llvm-project/commit/a7c57c4ec8100523e200ed1f608e1efbfd43a2f6
DIFF: https://github.com/llvm/llvm-project/commit/a7c57c4ec8100523e200ed1f608e1efbfd43a2f6.diff

LOG: tsan: don't consider debug calls as calls

Tsan pass does 2 optimizations based on presence of calls:
1. Don't emit function entry/exit callbacks if there are no calls
and no memory accesses.
2. Combine read/write of the same variable if there are no
intervening calls.
However, all debug info is represented as CallInst as well
and thus effectively disables these optimizations.
Don't consider debug info calls as calls.

Reviewed By: glider, melver

Differential Revision: https://reviews.llvm.org/D114079

Added: 
    llvm/test/Instrumentation/ThreadSanitizer/debug_calls.ll

Modified: 
    llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
index b967b37b4fda5..f98e39d751f4d 100644
--- a/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
@@ -585,7 +585,8 @@ bool ThreadSanitizer::sanitizeFunction(Function &F,
         AtomicAccesses.push_back(&Inst);
       else if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
         LocalLoadsAndStores.push_back(&Inst);
-      else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
+      else if ((isa<CallInst>(Inst) && !isa<DbgInfoIntrinsic>(Inst)) ||
+               isa<InvokeInst>(Inst)) {
         if (CallInst *CI = dyn_cast<CallInst>(&Inst))
           maybeMarkSanitizerLibraryCallNoBuiltin(CI, &TLI);
         if (isa<MemIntrinsic>(Inst))

diff  --git a/llvm/test/Instrumentation/ThreadSanitizer/debug_calls.ll b/llvm/test/Instrumentation/ThreadSanitizer/debug_calls.ll
new file mode 100644
index 0000000000000..f99f5eccf5352
--- /dev/null
+++ b/llvm/test/Instrumentation/ThreadSanitizer/debug_calls.ll
@@ -0,0 +1,65 @@
+; RUN: opt < %s -tsan -S | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @Increment(i32* nocapture %0) local_unnamed_addr sanitize_thread !dbg !7 {
+  call void @llvm.dbg.value(metadata i32* %0, metadata !14, metadata !DIExpression()), !dbg !16
+  %2 = load i32, i32* %0, align 4, !dbg !17, !tbaa !18
+  call void @llvm.dbg.value(metadata i32 %2, metadata !15, metadata !DIExpression()), !dbg !16
+  %3 = add nsw i32 %2, 1, !dbg !22
+  store i32 %3, i32* %0, align 4, !dbg !23, !tbaa !18
+  ret void, !dbg !24
+}
+; CHECK-LABEL: define void @Increment
+; CHECK-NOT: __tsan_read4
+; CHECK: __tsan_write4
+; CHECK: ret void
+
+define i32 @NoAccesses(i32 %0) local_unnamed_addr sanitize_thread !dbg !25 {
+  call void @llvm.dbg.value(metadata i32 %0, metadata !29, metadata !DIExpression()), !dbg !30
+  %2 = add nsw i32 %0, 1, !dbg !31
+  ret i32 %2, !dbg !32
+}
+; CHECK-LABEL: define i32 @NoAccesses
+; CHECK-NOT: __tsan_func_entry
+; CHECK-NOT: __tsan_func_exit
+; CHECK: ret i32
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5}
+!llvm.ident = !{!6}
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/")
+!2 = !{i32 7, !"Dwarf Version", i32 4}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 7, !"uwtable", i32 1}
+!6 = !{!"clang"}
+!7 = distinct !DISubprogram(name: "Increment", scope: !8, file: !8, line: 1, type: !9, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !13)
+!8 = !DIFile(filename: "test.c", directory: "")
+!9 = !DISubroutineType(types: !10)
+!10 = !{null, !11}
+!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64)
+!12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!13 = !{!14, !15}
+!14 = !DILocalVariable(name: "a", arg: 1, scope: !7, file: !8, line: 1, type: !11)
+!15 = !DILocalVariable(name: "x", scope: !7, file: !8, line: 2, type: !12)
+!16 = !DILocation(line: 0, scope: !7)
+!17 = !DILocation(line: 2, column: 11, scope: !7)
+!18 = !{!19, !19, i64 0}
+!19 = !{!"int", !20, i64 0}
+!20 = !{!"omnipotent char", !21, i64 0}
+!21 = !{!"Simple C/C++ TBAA"}
+!22 = !DILocation(line: 3, column: 10, scope: !7)
+!23 = !DILocation(line: 3, column: 6, scope: !7)
+!24 = !DILocation(line: 4, column: 1, scope: !7)
+!25 = distinct !DISubprogram(name: "NoAccesses", scope: !8, file: !8, line: 6, type: !26, scopeLine: 6, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !28)
+!26 = !DISubroutineType(types: !27)
+!27 = !{!12, !12}
+!28 = !{!29}
+!29 = !DILocalVariable(name: "a", arg: 1, scope: !25, file: !8, line: 6, type: !12)
+!30 = !DILocation(line: 0, scope: !25)
+!31 = !DILocation(line: 7, column: 12, scope: !25)
+!32 = !DILocation(line: 7, column: 3, scope: !25)