Be careful when looking through a vbit_convert. Optimizing this:
(vector_shuffle
(vbitconvert (vbuildvector (copyfromreg v4f32), 1, v4f32), 4, f32),
(undef, undef, undef, undef), (0, 0, 0, 0), 4, f32)
to the
vbitconvert
is a very bad idea.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30989 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index ba90e23..a27adba 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3108,8 +3108,17 @@
// all scalar elements the same.
if (isSplat) {
SDNode *V = N0.Val;
- if (V->getOpcode() == ISD::VBIT_CONVERT)
- V = V->getOperand(0).Val;
+
+ // If this is a vbit convert that changes the element type of the vector but
+ // not the number of vector elements, look through it. Be careful not to
+ // look though conversions that change things like v4f32 to v2f64.
+ if (V->getOpcode() == ISD::VBIT_CONVERT) {
+ SDOperand ConvInput = V->getOperand(0);
+ if (NumElts ==
+ ConvInput.getConstantOperandVal(ConvInput.getNumOperands()-2))
+ V = ConvInput.Val;
+ }
+
if (V->getOpcode() == ISD::VBUILD_VECTOR) {
unsigned NumElems = V->getNumOperands()-2;
if (NumElems > BaseIdx) {