[PATCH] D79392: [SanitizerCoverage] Replace the unconditional store with a load, then a conditional store.

[Pratyai Mazumder via Phabricator via llvm-commits]

pratyai updated this revision to Diff 262037.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D79392/new/

https://reviews.llvm.org/D79392

Files:
  llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
  llvm/test/Instrumentation/SanitizerCoverage/inline-bool-flag.ll


Index: llvm/test/Instrumentation/SanitizerCoverage/inline-bool-flag.ll
===================================================================
--- llvm/test/Instrumentation/SanitizerCoverage/inline-bool-flag.ll
+++ llvm/test/Instrumentation/SanitizerCoverage/inline-bool-flag.ll
@@ -7,7 +7,13 @@
 define void @foo() {
 entry:
 ; CHECK: @__sancov_gen_ = private global [1 x i1] zeroinitializer, section "__sancov_bools", comdat($foo), align 1, !associated !0
+; CHECK: %0 = load i1, i1* getelementptr inbounds ([1 x i1], [1 x i1]* @__sancov_gen_, i64 0, i64 0), align 1, !nosanitize !1
+; CHECK: %1 = xor i1 %0, true
+; CHECK: br i1 %1, label %2, label %3
+; CHECK: 2: ; preds = %entry
 ; CHECK: store i1 true, i1* getelementptr inbounds ([1 x i1], [1 x i1]* @__sancov_gen_, i64 0, i64 0), align 1, !nosanitize !1
+; CHECK: br label %3
+; CHECK: 3: ; preds = %entry, %2
   ret void
 }
 ; CHECK: call void @__sanitizer_cov_bool_flag_init(i1* bitcast (i1** @__start___sancov_bools to i1*), i1* bitcast (i1** @__stop___sancov_bools to i1*))
Index: llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
+++ llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
@@ -945,7 +945,11 @@
     auto FlagPtr = IRB.CreateGEP(
         FunctionBoolArray->getValueType(), FunctionBoolArray,
         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
-    auto Store = IRB.CreateStore(ConstantInt::getTrue(Int1Ty), FlagPtr);
+    auto Load = IRB.CreateLoad(Int1Ty, FlagPtr);
+    auto ThenTerm = SplitBlockAndInsertIfThen(IRB.CreateNot(Load), &*IP, false);
+    IRBuilder<> ThenIRB(ThenTerm);
+    auto Store = ThenIRB.CreateStore(ConstantInt::getTrue(Int1Ty), FlagPtr);
+    SetNoSanitizeMetadata(Load);
     SetNoSanitizeMetadata(Store);
   }
   if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {


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