Handle ands with 0 and shifts by 0 correctly. These aren't
common, but indvars shouldn't crash on them. This fixes PR4054.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70051 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 409bad9..495290d 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -1754,6 +1754,8 @@
// For an expression like x&255 that merely masks off the high bits,
// use zext(trunc(x)) as the SCEV expression.
if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) {
+ if (CI->isNullValue())
+ return getSCEV(U->getOperand(1));
const APInt &A = CI->getValue();
unsigned Ones = A.countTrailingOnes();
if (APIntOps::isMask(Ones, A))
@@ -1818,10 +1820,15 @@
if (Instruction *L = dyn_cast<Instruction>(U->getOperand(0)))
if (L->getOpcode() == Instruction::Shl &&
L->getOperand(1) == U->getOperand(1)) {
- uint64_t Amt = getTypeSizeInBits(U->getType()) - CI->getZExtValue();
+ unsigned BitWidth = getTypeSizeInBits(U->getType());
+ uint64_t Amt = BitWidth - CI->getZExtValue();
+ if (Amt == BitWidth)
+ return getSCEV(L->getOperand(0)); // shift by zero --> noop
+ if (Amt > BitWidth)
+ return getIntegerSCEV(0, U->getType()); // value is undefined
return
getSignExtendExpr(getTruncateExpr(getSCEV(L->getOperand(0)),
- IntegerType::get(Amt)),
+ IntegerType::get(Amt)),
U->getType());
}
break;