[InstCombine] Shift amount reassociation: fixup constantexpr handling (PR42484)

I was actually wondering if there was some nicer way than m_Value()+cast,
but apparently what i was really "subconsciously" thinking about
was correctness issue.

hasNoUnsignedWrap()/hasNoUnsignedWrap() exist for Instruction,
not for BinaryOperator, so let's just use m_Instruction(),
thus both avoiding a cast, and a crash.

Fixes https://bugs.llvm.org/show_bug.cgi?id=42484,
      https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15587

llvm-svn: 364915

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
index 1558795b530..0bbecde2184 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -29,12 +29,12 @@ static Instruction *
 reassociateShiftAmtsOfTwoSameDirectionShifts(BinaryOperator *Sh0,
                                              const SimplifyQuery &SQ) {
   // Look for:  (x shiftopcode ShAmt0) shiftopcode ShAmt1
-  Value *X, *ShAmt1, *Sh1Value, *ShAmt0;
+  Value *X, *ShAmt1, *ShAmt0;
+  Instruction *Sh1;
   if (!match(Sh0, m_Shift(m_CombineAnd(m_Shift(m_Value(X), m_Value(ShAmt1)),
-                                       m_Value(Sh1Value)),
+                                       m_Instruction(Sh1)),
                           m_Value(ShAmt0))))
     return nullptr;
-  auto *Sh1 = cast<BinaryOperator>(Sh1Value);
 
   // The shift opcodes must be identical.
   Instruction::BinaryOps ShiftOpcode = Sh0->getOpcode();