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[X86][SSE] combineScalarToVector - only reuse broadcasts for scalar_to_vector if the source operands scalar types match

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We were hitting an issue when the scalar_to_vector source was being implicitly truncated (in this case to i8 to vXi1) but we were also using the i8 source in a broadcast to a vXi8 value.

Fixes PR50374
This commit is contained in:
Simon Pilgrim 2021-06-02 22:05:14 +01:00
parent fc07b73b83
commit 7b5702378b
2 changed files with 45 additions and 10 deletions
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24
lib/Target/X86/X86ISelLowering.cpp
View File

@ -50473,16 +50473,20 @@ static SDValue combineScalarToVector(SDNode *N, SelectionDAG &DAG) {
// See if we're broadcasting the scalar value, in which case just reuse that.
// Ensure the same SDValue from the SDNode use is being used.
for (SDNode *User : Src->uses())
if (User->getOpcode() == X86ISD::VBROADCAST && Src == User->getOperand(0)) {
unsigned SizeInBits = VT.getFixedSizeInBits();
unsigned BroadcastSizeInBits = User->getValueSizeInBits(0).getFixedSize();
if (BroadcastSizeInBits == SizeInBits)
return SDValue(User, 0);
if (BroadcastSizeInBits > SizeInBits)
return extractSubVector(SDValue(User, 0), 0, DAG, DL, SizeInBits);
// TODO: Handle BroadcastSizeInBits < SizeInBits when we have test coverage.
}
if (VT.getScalarType() == Src.getValueType())
for (SDNode *User : Src->uses())
if (User->getOpcode() == X86ISD::VBROADCAST &&
Src == User->getOperand(0)) {
unsigned SizeInBits = VT.getFixedSizeInBits();
unsigned BroadcastSizeInBits =
User->getValueSizeInBits(0).getFixedSize();
if (BroadcastSizeInBits == SizeInBits)
return SDValue(User, 0);
if (BroadcastSizeInBits > SizeInBits)
return extractSubVector(SDValue(User, 0), 0, DAG, DL, SizeInBits);
// TODO: Handle BroadcastSizeInBits < SizeInBits when we have test
// coverage.
}
return SDValue();
}

31
test/CodeGen/X86/pr50374.ll Normal file
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@ -0,0 +1,31 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=skx | FileCheck %s
define void @PR50374() {
; CHECK-LABEL: PR50374:
; CHECK: # %bb.0: # %while.84.body.preheader
; CHECK-NEXT: .p2align 4, 0x90
; CHECK-NEXT: .LBB0_1: # %vector.body1999
; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
; CHECK-NEXT: jmp .LBB0_1
while.84.body.preheader:
%0 = load i8, i8* undef, align 1
%1 = load i8, i8* undef, align 4
%.not14.2.2 = icmp eq i8 0, 0
%2 = and i8 %0, 1
%.not14.1.2 = icmp eq i8 %2, 0
%3 = select i1 %.not14.2.2, i1 %.not14.1.2, i1 false
%.not14.2361 = icmp eq i8 0, 0
%4 = select i1 %3, i1 %.not14.2361, i1 false
%add.10961.i.2.2 = select reassoc nsz contract i1 %4, float 0.000000e+00, float 0x7FF8000000000000
%broadcast.splatinsert2024 = insertelement <8 x float> poison, float %add.10961.i.2.2, i32 0
%broadcast.splat2025 = shufflevector <8 x float> %broadcast.splatinsert2024, <8 x float> poison, <8 x i32> zeroinitializer
%broadcast.splatinsert2049 = insertelement <8 x i8> poison, i8 %1, i32 0
%broadcast.splat2050 = shufflevector <8 x i8> %broadcast.splatinsert2049, <8 x i8> poison, <8 x i32> zeroinitializer
br label %vector.body1999
vector.body1999: ; preds = %vector.body1999, %while.84.body.preheader
%predphi2026 = select <8 x i1> undef, <8 x float> undef, <8 x float> %broadcast.splat2025
%predphi2051 = select <8 x i1> undef, <8 x i8> %broadcast.splat2050, <8 x i8> undef
br label %vector.body1999
}