[InstCombine] Check for out of range ashr values using APInt before calling getZExtValue

Reduced from oss-fuzz #5032 test case

llvm-svn: 322078

1 files changed, 5 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
index 3d379ad68b6..a04a3cec09e 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -818,7 +818,7 @@ Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
   Type *Ty = I.getType();
   unsigned BitWidth = Ty->getScalarSizeInBits();
   const APInt *ShAmtAPInt;
-  if (match(Op1, m_APInt(ShAmtAPInt))) {
+  if (match(Op1, m_APInt(ShAmtAPInt)) && ShAmtAPInt->ult(BitWidth)) {
     unsigned ShAmt = ShAmtAPInt->getZExtValue();
 
     // If the shift amount equals the difference in width of the destination
@@ -832,7 +832,8 @@ Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
     // We can't handle (X << C1) >>s C2. It shifts arbitrary bits in. However,
     // we can handle (X <<nsw C1) >>s C2 since it only shifts in sign bits.
     const APInt *ShOp1;
-    if (match(Op0, m_NSWShl(m_Value(X), m_APInt(ShOp1)))) {
+    if (match(Op0, m_NSWShl(m_Value(X), m_APInt(ShOp1))) &&
+        ShOp1->ult(BitWidth)) {
       unsigned ShlAmt = ShOp1->getZExtValue();
       if (ShlAmt < ShAmt) {
         // (X <<nsw C1) >>s C2 --> X >>s (C2 - C1)
@@ -850,7 +851,8 @@ Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
       }
     }
 
-    if (match(Op0, m_AShr(m_Value(X), m_APInt(ShOp1)))) {
+    if (match(Op0, m_AShr(m_Value(X), m_APInt(ShOp1))) &&
+        ShOp1->ult(BitWidth)) {
       unsigned AmtSum = ShAmt + ShOp1->getZExtValue();
       // Oversized arithmetic shifts replicate the sign bit.
       AmtSum = std::min(AmtSum, BitWidth - 1);