[llvm] 6b6f272 - [DAGCombiner] Require same type of splat & element for build_vector (#88284)
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Thu Apr 11 19:14:00 PDT 2024
Author: Feng Zou
Date: 2024-04-12T10:13:56+08:00
New Revision: 6b6f272f355a2cbc753e9057dd7aefb1a74a0409
URL: https://github.com/llvm/llvm-project/commit/6b6f272f355a2cbc753e9057dd7aefb1a74a0409
DIFF: https://github.com/llvm/llvm-project/commit/6b6f272f355a2cbc753e9057dd7aefb1a74a0409.diff
LOG: [DAGCombiner] Require same type of splat & element for build_vector (#88284)
Only allow to change build_vector to concat_vector when the splat type
and vector element type is same. It's to fix assertion of failing to
bitcast types of different sizes.
Added:
llvm/test/CodeGen/X86/buildvec-bitcast.ll
Modified:
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 95c1cde0b9347b..24f50b87c4cf2f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -23428,7 +23428,10 @@ SDValue DAGCombiner::visitBUILD_VECTOR(SDNode *N) {
// If X is a build_vector itself, the concat can become a larger build_vector.
// TODO: Maybe this is useful for non-splat too?
if (!LegalOperations) {
- if (SDValue Splat = cast<BuildVectorSDNode>(N)->getSplatValue()) {
+ SDValue Splat = cast<BuildVectorSDNode>(N)->getSplatValue();
+ // Only change build_vector to a concat_vector if the splat value type is
+ // same as the vector element type.
+ if (Splat && Splat.getValueType() == VT.getVectorElementType()) {
Splat = peekThroughBitcasts(Splat);
EVT SrcVT = Splat.getValueType();
if (SrcVT.isVector()) {
@@ -23437,8 +23440,8 @@ SDValue DAGCombiner::visitBUILD_VECTOR(SDNode *N) {
SrcVT.getVectorElementType(), NumElts);
if (!LegalTypes || TLI.isTypeLegal(NewVT)) {
SmallVector<SDValue, 8> Ops(N->getNumOperands(), Splat);
- SDValue Concat = DAG.getNode(ISD::CONCAT_VECTORS, SDLoc(N),
- NewVT, Ops);
+ SDValue Concat =
+ DAG.getNode(ISD::CONCAT_VECTORS, SDLoc(N), NewVT, Ops);
return DAG.getBitcast(VT, Concat);
}
}
diff --git a/llvm/test/CodeGen/X86/buildvec-bitcast.ll b/llvm/test/CodeGen/X86/buildvec-bitcast.ll
new file mode 100644
index 00000000000000..980fd2dee0915b
--- /dev/null
+++ b/llvm/test/CodeGen/X86/buildvec-bitcast.ll
@@ -0,0 +1,25 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
+; RUN: llc < %s -mtriple=x86_64 -mattr=avx512bw | FileCheck %s
+
+; Verify that the DAGCombiner doesn't change build_vector to concat_vectors if
+; the vector element type is
diff erent than splat type. The example here:
+; v8i1 = build_vector (i8 (bitcast (v8i1 X))), ..., (i8 (bitcast (v8i1 X))))
+
+define <8 x i1> @foo(<8 x i1> %mask.i1) {
+; CHECK-LABEL: foo:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: vxorps %xmm0, %xmm0, %xmm0
+; CHECK-NEXT: retq
+entry:
+ %0 = and <8 x i1> %mask.i1, <i1 true, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false, i1 false>
+ %1 = bitcast <8 x i1> %0 to i8
+ %2 = icmp ne i8 %1, 0
+ %insert54 = insertelement <8 x i1> zeroinitializer, i1 %2, i64 0
+ %splat55 = shufflevector <8 x i1> %insert54, <8 x i1> zeroinitializer, <8 x i32> zeroinitializer
+ %3 = and <8 x i1> %0, %splat55
+ br label %end
+
+end: ; preds = %entry
+ %4 = select <8 x i1> %3, <8 x i1> zeroinitializer, <8 x i1> zeroinitializer
+ ret <8 x i1> %4
+}
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