msan, codegen, instcombine: Keep more lifetime markers used for msan

Reviewers: eugenis

Subscribers: hiraditya, cfe-commits, #sanitizers, llvm-commits

Tags: #clang, #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D66695

llvm-svn: 369979

clang/lib/CodeGen/CGExpr.cpp

@@ -516,13 +516,12 @@ EmitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *M) {
 
       // Avoid creating a conditional cleanup just to hold an llvm.lifetime.end
       // marker. Instead, start the lifetime of a conditional temporary earlier
-      // so that it's unconditional. Don't do this in ASan's use-after-scope
-      // mode so that it gets the more precise lifetime marks. If the type has
-      // a non-trivial destructor, we'll have a cleanup block for it anyway,
-      // so this typically doesn't help; skip it in that case.
+      // so that it's unconditional. Don't do this with sanitizers which need
+      // more precise lifetime marks.
       ConditionalEvaluation *OldConditional = nullptr;
       CGBuilderTy::InsertPoint OldIP;
       if (isInConditionalBranch() && !E->getType().isDestructedType() &&
+          !SanOpts.has(SanitizerKind::Memory) &&
           !CGM.getCodeGenOpts().SanitizeAddressUseAfterScope) {
         OldConditional = OutermostConditional;
         OutermostConditional = nullptr;

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -47,13 +47,9 @@ static bool shouldEmitLifetimeMarkers(const CodeGenOptions &CGOpts,
   if (CGOpts.DisableLifetimeMarkers)
     return false;
 
-  // Disable lifetime markers in msan builds.
-  // FIXME: Remove this when msan works with lifetime markers.
-  if (LangOpts.Sanitize.has(SanitizerKind::Memory))
-    return false;
-
-  // Asan uses markers for use-after-scope checks.
-  if (CGOpts.SanitizeAddressUseAfterScope)
+  // Sanitizers may use markers.
+  if (CGOpts.SanitizeAddressUseAfterScope ||
+      LangOpts.Sanitize.has(SanitizerKind::Memory))
     return true;
 
   // For now, only in optimized builds.

clang/test/CodeGen/lifetime-sanitizer.c

@@ -2,6 +2,9 @@
 // RUN: %clang -target x86_64-linux-gnu -S -emit-llvm -o - -O0 \
 // RUN:     -fsanitize=address -fsanitize-address-use-after-scope %s | \
 // RUN:     FileCheck %s -check-prefix=LIFETIME
+// RUN: %clang -target x86_64-linux-gnu -S -emit-llvm -o - -O0 \
+// RUN:     -fsanitize=memory %s | \
+// RUN:     FileCheck %s -check-prefix=LIFETIME
 
 extern int bar(char *A, int n);
 

clang/test/CodeGenCXX/lifetime-sanitizer.cpp

@@ -3,6 +3,9 @@
 // RUN: %clang -w -target x86_64-linux-gnu -S -emit-llvm -o - -fno-exceptions -O0 \
 // RUN:     -fsanitize=address -fsanitize-address-use-after-scope %s | \
 // RUN:     FileCheck %s -check-prefixes=CHECK,LIFETIME
+// RUN: %clang -w -target x86_64-linux-gnu -S -emit-llvm -o - -fno-exceptions -O0 \
+// RUN:     -fsanitize=memory %s | \
+// RUN:     FileCheck %s -check-prefixes=CHECK,LIFETIME
 
 extern int bar(char *A, int n);
 

compiler-rt/test/msan/loop-scope.cpp

@@ -0,0 +1,18 @@
+// RUN: %clangxx_msan -O2 %s -o %t && \
+// RUN:     not %run %t 2>&1 | FileCheck %s
+
+#include <stdlib.h>
+
+int *p;
+
+int main() {
+  for (int i = 0; i < 3; i++) {
+    int x;
+    if (i == 0)
+      x = 0;
+    p = &x;
+  }
+  return *p; // BOOM
+  // CHECK: WARNING: MemorySanitizer: use-of-uninitialized-value
+  // CHECK:  #0 0x{{.*}} in main {{.*}}loop-scope.cpp:[[@LINE-2]]
+}

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -3885,6 +3885,7 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
     // Asan needs to poison memory to detect invalid access which is possible
     // even for empty lifetime range.
     if (II->getFunction()->hasFnAttribute(Attribute::SanitizeAddress) ||
+        II->getFunction()->hasFnAttribute(Attribute::SanitizeMemory) ||
         II->getFunction()->hasFnAttribute(Attribute::SanitizeHWAddress))
       break;
 

llvm/test/Transforms/InstCombine/lifetime-sanitizer.ll

@@ -34,6 +34,21 @@ entry:
   ret void
 }
 
+define void @msan() sanitize_memory {
+entry:
+  ; CHECK-LABEL: @msan(
+  %text = alloca i8, align 1
+
+  call void @llvm.lifetime.start.p0i8(i64 1, i8* %text)
+  call void @llvm.lifetime.end.p0i8(i64 1, i8* %text)
+  ; CHECK: call void @llvm.lifetime.start
+  ; CHECK-NEXT: call void @llvm.lifetime.end
+
+  call void @foo(i8* %text) ; Keep alloca alive
+
+  ret void
+}
+
 define void @no_asan() {
 entry:
   ; CHECK-LABEL: @no_asan(