[InstCombine] Don't divide by zero when evaluating a potential transform
Trivial multiplication by zero may survive the worklist. We tried to
reassociate the multiplication with a division instruction, causing us
to divide by zero; bail out instead.
This fixes PR24726.
llvm-svn: 246939
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index a554e9f..bb3d928 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -95,6 +95,14 @@
assert(C1.getBitWidth() == C2.getBitWidth() &&
"Inconsistent width of constants!");
+ // Bail if we will divide by zero.
+ if (C2.isMinValue())
+ return false;
+
+ // Bail if we would divide INT_MIN by -1.
+ if (IsSigned && C1.isMinSignedValue() && C2.isAllOnesValue())
+ return false;
+
APInt Remainder(C1.getBitWidth(), /*Val=*/0ULL, IsSigned);
if (IsSigned)
APInt::sdivrem(C1, C2, Quotient, Remainder);