[InstSimplify] Guard against large shift amounts.
These are always UB, but can happen for large integer inputs. Testing it
is very fragile as -simplifycfg will nuke the UB top-down.
llvm-svn: 339515
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index a64409b..dee681a 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -1338,7 +1338,7 @@
const KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
const unsigned Width = Op0->getType()->getScalarSizeInBits();
const unsigned EffWidthY = Width - YKnown.countMinLeadingZeros();
- if (EffWidthY <= ShRAmt->getZExtValue())
+ if (ShRAmt->uge(EffWidthY))
return X;
}
@@ -1880,9 +1880,9 @@
match(Op0, m_c_Or(m_CombineAnd(m_NUWShl(m_Value(X), m_APInt(ShAmt)),
m_Value(XShifted)),
m_Value(Y)))) {
- const unsigned ShftCnt = ShAmt->getZExtValue();
- const KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
const unsigned Width = Op0->getType()->getScalarSizeInBits();
+ const unsigned ShftCnt = ShAmt->getLimitedValue(Width);
+ const KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
const unsigned EffWidthY = Width - YKnown.countMinLeadingZeros();
if (EffWidthY <= ShftCnt) {
const KnownBits XKnown = computeKnownBits(X, Q.DL, 0, Q.AC, Q.CxtI,