Scalar shifts in the OpenCL specification (as of v. 1.2) are defined to be
with respect to the lower "left-hand-side bitwidth" bits, even when negative);
see OpenCL spec 6.3j. This patch both implements this behaviour in the code
generator and "constant folding" bits of Sema, and also prevents tests
to detect undefinedness in terms of the weaker C99 or C++ specifications
from being applied.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171755 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp
index eb62343..7ec4bc2 100644
--- a/lib/CodeGen/CGExprScalar.cpp
+++ b/lib/CodeGen/CGExprScalar.cpp
@@ -429,6 +429,8 @@
// Check for undefined division and modulus behaviors.
void EmitUndefinedBehaviorIntegerDivAndRemCheck(const BinOpInfo &Ops,
llvm::Value *Zero,bool isDiv);
+ // Common helper for getting how wide LHS of shift is.
+ static Value *GetWidthMinusOneValue(Value* LHS,Value* RHS);
Value *EmitDiv(const BinOpInfo &Ops);
Value *EmitRem(const BinOpInfo &Ops);
Value *EmitAdd(const BinOpInfo &Ops);
@@ -2365,6 +2367,11 @@
return Builder.CreateExactSDiv(diffInChars, divisor, "sub.ptr.div");
}
+Value *ScalarExprEmitter::GetWidthMinusOneValue(Value* LHS,Value* RHS) {
+ unsigned Width = cast<llvm::IntegerType>(LHS->getType())->getBitWidth();
+ return llvm::ConstantInt::get(RHS->getType(), Width - 1);
+}
+
Value *ScalarExprEmitter::EmitShl(const BinOpInfo &Ops) {
// LLVM requires the LHS and RHS to be the same type: promote or truncate the
// RHS to the same size as the LHS.
@@ -2372,11 +2379,9 @@
if (Ops.LHS->getType() != RHS->getType())
RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
- if (CGF.getLangOpts().SanitizeShift &&
- isa<llvm::IntegerType>(Ops.LHS->getType())) {
- unsigned Width = cast<llvm::IntegerType>(Ops.LHS->getType())->getBitWidth();
- llvm::Value *WidthMinusOne =
- llvm::ConstantInt::get(RHS->getType(), Width - 1);
+ if (CGF.getLangOpts().SanitizeShift && !CGF.getLangOpts().OpenCL
+ && isa<llvm::IntegerType>(Ops.LHS->getType())) {
+ llvm::Value *WidthMinusOne = GetWidthMinusOneValue(Ops.LHS, RHS);
// FIXME: Emit the branching explicitly rather than emitting the check
// twice.
EmitBinOpCheck(Builder.CreateICmpULE(RHS, WidthMinusOne), Ops);
@@ -2401,6 +2406,9 @@
EmitBinOpCheck(Builder.CreateICmpEQ(BitsShiftedOff, Zero), 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");
}
@@ -2412,12 +2420,13 @@
if (Ops.LHS->getType() != RHS->getType())
RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
- if (CGF.getLangOpts().SanitizeShift &&
- isa<llvm::IntegerType>(Ops.LHS->getType())) {
- unsigned Width = cast<llvm::IntegerType>(Ops.LHS->getType())->getBitWidth();
- llvm::Value *WidthVal = llvm::ConstantInt::get(RHS->getType(), Width);
- EmitBinOpCheck(Builder.CreateICmpULT(RHS, WidthVal), Ops);
- }
+ if (CGF.getLangOpts().SanitizeShift && !CGF.getLangOpts().OpenCL
+ && isa<llvm::IntegerType>(Ops.LHS->getType()))
+ EmitBinOpCheck(Builder.CreateICmpULE(RHS, GetWidthMinusOneValue(Ops.LHS, RHS)), 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");