[ConstnatFolding] Teach the folder how to fold ConstantVector
A ConstantVector can have ConstantExpr operands and vice versa.
However, the folder had no ability to fold ConstantVectors which, in
some cases, was an optimization barrier.
Instead, rephrase the folder in terms of Constants instead of
ConstantExprs and teach callers how to deal with failure.
llvm-svn: 277099
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
index 08e16a7..279eaad 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -194,8 +194,10 @@
else
V = IC.Builder->CreateLShr(C, NumBits);
// If we got a constantexpr back, try to simplify it with TD info.
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
- V = ConstantFoldConstantExpression(CE, DL, IC.getTargetLibraryInfo());
+ if (auto *C = dyn_cast<Constant>(V))
+ if (auto *FoldedC =
+ ConstantFoldConstant(C, DL, IC.getTargetLibraryInfo()))
+ V = FoldedC;
return V;
}