[gcov] Add nosanitize metadata to memory access instructions inserted by emitProfileNotes()

This patch adds nosantize metadata to memory access instructions inserted by gcov emitProfileNotes(), making sanitizers skip these instructions when gcov and sanitizer are used together.

Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D150460

Author: Enna1

llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp

@@ -919,15 +919,21 @@ bool GCOVProfiler::emitProfileNotes(
           IRBuilder<> Builder(E.Place, E.Place->getFirstInsertionPt());
           Value *V = Builder.CreateConstInBoundsGEP2_64(
               Counters->getValueType(), Counters, 0, I);
+          // Disable sanitizers to decrease size bloat. We don't expect
+          // sanitizers to catch interesting issues.
+          Instruction *Inst;
           if (Options.Atomic) {
-            Builder.CreateAtomicRMW(AtomicRMWInst::Add, V, Builder.getInt64(1),
-                                    MaybeAlign(), AtomicOrdering::Monotonic);
+            Inst = Builder.CreateAtomicRMW(AtomicRMWInst::Add, V,
+                                           Builder.getInt64(1), MaybeAlign(),
+                                           AtomicOrdering::Monotonic);
           } else {
-            Value *Count =
+            LoadInst *OldCount =
                 Builder.CreateLoad(Builder.getInt64Ty(), V, "gcov_ctr");
-            Count = Builder.CreateAdd(Count, Builder.getInt64(1));
-            Builder.CreateStore(Count, V);
+            OldCount->setNoSanitizeMetadata();
+            Value *NewCount = Builder.CreateAdd(OldCount, Builder.getInt64(1));
+            Inst = Builder.CreateStore(NewCount, V);
           }
+          Inst->setNoSanitizeMetadata();
         }
       }
     }

llvm/test/Transforms/GCOVProfiling/nosanitize.ll

@@ -0,0 +1,34 @@
+;; Ensure that the loads, stores, and atomicrmw adds for gcov have nosanitize metadata.
+; RUN: rm -rf %t && mkdir %t && cd %t
+; RUN: opt < %s -S -passes=insert-gcov-profiling | FileCheck %s
+; RUN: opt < %s -S -passes=insert-gcov-profiling -gcov-atomic-counter | FileCheck %s --check-prefixes=CHECK-ATOMIC-COUNTER
+
+; CHECK-LABEL: void @empty()
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    %gcov_ctr = load i64, ptr @__llvm_gcov_ctr, align 4, !dbg [[DBG:![0-9]+]], !nosanitize [[NOSANITIZE:![0-9]+]]
+; CHECK-NEXT:    %0 = add i64 %gcov_ctr, 1, !dbg [[DBG]]
+; CHECK-NEXT:    store i64 %0, ptr @__llvm_gcov_ctr, align 4, !dbg [[DBG]], !nosanitize [[NOSANITIZE]]
+; CHECK-NEXT:    ret void, !dbg [[DBG]]
+
+; CHECK-ATOMIC-COUNTER-LABEL: void @empty()
+; CHECK-ATOMIC-COUNTER-NEXT:  entry:
+; CHECK-ATOMIC-COUNTER-NEXT:    %0 = atomicrmw add ptr @__llvm_gcov_ctr, i64 1 monotonic, align 8, !dbg [[DBG:![0-9]+]], !nosanitize [[NOSANITIZE:![0-9]+]]
+; CHECK-ATOMIC-COUNTER-NEXT:    ret void, !dbg [[DBG]]
+
+define dso_local void @empty() !dbg !5 {
+entry:
+  ret void, !dbg !8
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "a.c", directory: "")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 5}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = distinct !DISubprogram(name: "empty", scope: !1, file: !1, line: 1, type: !6, scopeLine: 1, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!6 = !DISubroutineType(types: !7)
+!7 = !{null}
+!8 = !DILocation(line: 2, column: 1, scope: !5)