[InstCombine] Fix miscompile in FoldSPFofSPF

We had a select of a cast of a select but attempted to replace the outer
select with the inner select dispite their incompatible types.

Patch by Anton Korobeynikov!

This fixes PR27236.

llvm-svn: 265805

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 7260dd2093d..8595996c29c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -642,6 +642,9 @@ Instruction *InstCombiner::FoldSPFofSPF(Instruction *Inner,
                                         Value *A, Value *B,
                                         Instruction &Outer,
                                         SelectPatternFlavor SPF2, Value *C) {
+  if (Outer.getType() != Inner->getType())
+    return nullptr;
+
   if (C == A || C == B) {
     // MAX(MAX(A, B), B) -> MAX(A, B)
     // MIN(MIN(a, b), a) -> MIN(a, b)