Fix logic for generating llvm.type.test()s

CodeGenFunction::EmitTypeMetadataCodeForVCall() could output an
llvm.assume(llvm.type.test())when CFI was enabled, optimizing out the
vcall check. This case was only reached when: 1) CFI-vcall was enabled,
2) -fwhole-program-tables was specified, and 3)
-fno-sanitize-trap=cfi-vcall was specified.

Patch by Vlad Tsyrklevich!

Differential Revision: https://reviews.llvm.org/D36013

llvm-svn: 309622

2 files changed, 19 insertions, 5 deletions

diff --git a/clang/lib/CodeGen/CGClass.cpp b/clang/lib/CodeGen/CGClass.cpp
index 50d702c6226..e27e518c7ea 100644
--- a/clang/lib/CodeGen/CGClass.cpp
+++ b/clang/lib/CodeGen/CGClass.cpp
@@ -2523,8 +2523,10 @@ LeastDerivedClassWithSameLayout(const CXXRecordDecl *RD) {
 void CodeGenFunction::EmitTypeMetadataCodeForVCall(const CXXRecordDecl *RD,
                                                    llvm::Value *VTable,
                                                    SourceLocation Loc) {
-  if (CGM.getCodeGenOpts().WholeProgramVTables &&
-      CGM.HasHiddenLTOVisibility(RD)) {
+  if (SanOpts.has(SanitizerKind::CFIVCall))
+    EmitVTablePtrCheckForCall(RD, VTable, CodeGenFunction::CFITCK_VCall, Loc);
+  else if (CGM.getCodeGenOpts().WholeProgramVTables &&
+           CGM.HasHiddenLTOVisibility(RD)) {
     llvm::Metadata *MD =
         CGM.CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
     llvm::Value *TypeId =
@@ -2536,9 +2538,6 @@ void CodeGenFunction::EmitTypeMetadataCodeForVCall(const CXXRecordDecl *RD,
                            {CastedVTable, TypeId});
     Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::assume), TypeTest);
   }
-
-  if (SanOpts.has(SanitizerKind::CFIVCall))
-    EmitVTablePtrCheckForCall(RD, VTable, CodeGenFunction::CFITCK_VCall, Loc);
 }
 
 void CodeGenFunction::EmitVTablePtrCheckForCall(const CXXRecordDecl *RD,
diff --git a/clang/test/CodeGenCXX/cfi-vcall-no-trap.cpp b/clang/test/CodeGenCXX/cfi-vcall-no-trap.cpp
new file mode 100644
index 00000000000..dbfe558065a
--- /dev/null
+++ b/clang/test/CodeGenCXX/cfi-vcall-no-trap.cpp
@@ -0,0 +1,15 @@
+// Only output llvm.assume(llvm.type.test()) if cfi-vcall is disabled and whole-program-vtables is enabled
+// RUN: %clang_cc1 -fvisibility hidden -fsanitize=cfi-vcall -fwhole-program-vtables -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=CFI %s
+// RUN: %clang_cc1 -fvisibility hidden -fwhole-program-vtables -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=NOCFI %s
+
+struct S1 {
+  virtual void f();
+};
+
+// CHECK: define{{.*}}s1f
+// CHECK: llvm.type.test
+// CFI-NOT: llvm.assume
+// NOCFI: llvm.assume
+void s1f(S1 *s1) {
+  s1->f();
+}