Revert "[UBSan] Split -fsanitize=shift into -fsanitize=shift-base and -fsanitize=shift-exponent."

It's not that easy. If we're only checking -fsanitize=shift-base we
still need to verify that exponent has sane value, otherwise
UBSan-inserted checks for base will contain undefined behavior
themselves.

llvm-svn: 231409

1 files changed, 28 insertions, 32 deletions

diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 3544ce57366a..dc12dd84249b 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -2664,30 +2664,21 @@ Value *ScalarExprEmitter::EmitShl(const BinOpInfo &Ops) {
   if (Ops.LHS->getType() != RHS->getType())
     RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
 
-  // OpenCL 6.3j: shift values are effectively % word size of LHS.
-  if (CGF.getLangOpts().OpenCL)
-    RHS =
-        Builder.CreateAnd(RHS, GetWidthMinusOneValue(Ops.LHS, RHS), "shl.mask");
-  else if ((CGF.SanOpts.has(SanitizerKind::ShiftBase) ||
-            CGF.SanOpts.has(SanitizerKind::ShiftExponent)) &&
-           isa<llvm::IntegerType>(Ops.LHS->getType())) {
+  if (CGF.SanOpts.has(SanitizerKind::Shift) && !CGF.getLangOpts().OpenCL &&
+      isa<llvm::IntegerType>(Ops.LHS->getType())) {
     CodeGenFunction::SanitizerScope SanScope(&CGF);
-    SmallVector<std::pair<Value *, SanitizerKind>, 2> Checks;
-    llvm::Value *WidthMinusOne = nullptr;
-
-    if (CGF.SanOpts.has(SanitizerKind::ShiftExponent)) {
-      WidthMinusOne = GetWidthMinusOneValue(Ops.LHS, RHS);
-      llvm::Value *ValidExponent = Builder.CreateICmpULE(RHS, WidthMinusOne);
-      Checks.push_back(
-          std::make_pair(ValidExponent, SanitizerKind::ShiftExponent));
-    }
+    llvm::Value *WidthMinusOne = GetWidthMinusOneValue(Ops.LHS, RHS);
+    llvm::Value *Valid = Builder.CreateICmpULE(RHS, WidthMinusOne);
+
+    if (Ops.Ty->hasSignedIntegerRepresentation()) {
+      llvm::BasicBlock *Orig = Builder.GetInsertBlock();
+      llvm::BasicBlock *Cont = CGF.createBasicBlock("cont");
+      llvm::BasicBlock *CheckBitsShifted = CGF.createBasicBlock("check");
+      Builder.CreateCondBr(Valid, CheckBitsShifted, Cont);
 
-    if (CGF.SanOpts.has(SanitizerKind::ShiftBase) &&
-        Ops.Ty->hasSignedIntegerRepresentation()) {
-      if (WidthMinusOne == nullptr)
-        WidthMinusOne = GetWidthMinusOneValue(Ops.LHS, RHS);
       // Check whether we are shifting any non-zero bits off the top of the
       // integer.
+      CGF.EmitBlock(CheckBitsShifted);
       llvm::Value *BitsShiftedOff =
         Builder.CreateLShr(Ops.LHS,
                            Builder.CreateSub(WidthMinusOne, RHS, "shl.zeros",
@@ -2702,14 +2693,19 @@ Value *ScalarExprEmitter::EmitShl(const BinOpInfo &Ops) {
         BitsShiftedOff = Builder.CreateLShr(BitsShiftedOff, One);
       }
       llvm::Value *Zero = llvm::ConstantInt::get(BitsShiftedOff->getType(), 0);
-      llvm::Value *ValidBase = Builder.CreateICmpEQ(BitsShiftedOff, Zero);
-
-      Checks.push_back(std::make_pair(ValidBase, SanitizerKind::ShiftBase));
+      llvm::Value *SecondCheck = Builder.CreateICmpEQ(BitsShiftedOff, Zero);
+      CGF.EmitBlock(Cont);
+      llvm::PHINode *P = Builder.CreatePHI(Valid->getType(), 2);
+      P->addIncoming(Valid, Orig);
+      P->addIncoming(SecondCheck, CheckBitsShifted);
+      Valid = P;
     }
 
-    if (!Checks.empty())
-      EmitBinOpCheck(Checks, Ops);
+    EmitBinOpCheck(std::make_pair(Valid, SanitizerKind::Shift), Ops);
   }
+  // OpenCL 6.3j: shift values are effectively % word size of LHS.
+  if (CGF.getLangOpts().OpenCL)
+    RHS = Builder.CreateAnd(RHS, GetWidthMinusOneValue(Ops.LHS, RHS), "shl.mask");
 
   return Builder.CreateShl(Ops.LHS, RHS, "shl");
 }
@@ -2721,18 +2717,18 @@ Value *ScalarExprEmitter::EmitShr(const BinOpInfo &Ops) {
   if (Ops.LHS->getType() != RHS->getType())
     RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
 
-  // OpenCL 6.3j: shift values are effectively % word size of LHS.
-  if (CGF.getLangOpts().OpenCL)
-    RHS =
-        Builder.CreateAnd(RHS, GetWidthMinusOneValue(Ops.LHS, RHS), "shr.mask");
-  else if (CGF.SanOpts.has(SanitizerKind::ShiftExponent) &&
-           isa<llvm::IntegerType>(Ops.LHS->getType())) {
+  if (CGF.SanOpts.has(SanitizerKind::Shift) && !CGF.getLangOpts().OpenCL &&
+      isa<llvm::IntegerType>(Ops.LHS->getType())) {
     CodeGenFunction::SanitizerScope SanScope(&CGF);
     llvm::Value *Valid =
         Builder.CreateICmpULE(RHS, GetWidthMinusOneValue(Ops.LHS, RHS));
-    EmitBinOpCheck(std::make_pair(Valid, SanitizerKind::ShiftExponent), Ops);
+    EmitBinOpCheck(std::make_pair(Valid, SanitizerKind::Shift), Ops);
   }
 
+  // OpenCL 6.3j: shift values are effectively % word size of LHS.
+  if (CGF.getLangOpts().OpenCL)
+    RHS = Builder.CreateAnd(RHS, GetWidthMinusOneValue(Ops.LHS, RHS), "shr.mask");
+
   if (Ops.Ty->hasUnsignedIntegerRepresentation())
     return Builder.CreateLShr(Ops.LHS, RHS, "shr");
   return Builder.CreateAShr(Ops.LHS, RHS, "shr");