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[DAGCombine] Fix for PR35761

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I had falsely assumed that constant operands would be operand(1) of
the bin ops that may need their constant operand to be masked.

Bugzilla: https://bugs.llvm.org/show_bug.cgi?id=35761

Differential Revision: https://reviews.llvm.org/D41667


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@321991 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sam Parker 2018-01-08 13:21:24 +00:00
parent c5a9d9b7a5
commit 14e29de03d
2 changed files with 46 additions and 4 deletions
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14
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -3923,10 +3923,16 @@ bool DAGCombiner::BackwardsPropagateMask(SDNode *N, SelectionDAG &DAG) {
// Narrow any constants that need it.
for (auto *LogicN : NodesWithConsts) {
auto *C = cast<ConstantSDNode>(LogicN->getOperand(1));
SDValue And = DAG.getNode(ISD::AND, SDLoc(C), C->getValueType(0),
SDValue(C, 0), MaskOp);
DAG.UpdateNodeOperands(LogicN, LogicN->getOperand(0), And);
SDValue Op0 = LogicN->getOperand(0);
SDValue Op1 = LogicN->getOperand(1);
if (isa<ConstantSDNode>(Op0))
std::swap(Op0, Op1);
SDValue And = DAG.getNode(ISD::AND, SDLoc(Op1), Op1.getValueType(),
Op1, MaskOp);
DAG.UpdateNodeOperands(LogicN, Op0, And);
}
// Create narrow loads.

36
test/CodeGen/X86/pr35761.ll Normal file
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@ -0,0 +1,36 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -mtriple=x86_64-unknown-linux %s -o - | FileCheck %s
@x = global i8 0, align 1
@y = global i32 0, align 4
@z = global i24 0, align 4
define void @PR35761(i32 %call) {
; CHECK-LABEL: PR35761:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: movzbl {{.*}}(%rip), %eax
; CHECK-NEXT: andl $1, %eax
; CHECK-NEXT: movzbl {{.*}}(%rip), %ecx
; CHECK-NEXT: xorl $255, %ecx
; CHECK-NEXT: orl %eax, %ecx
; CHECK-NEXT: movw %cx, {{.*}}(%rip)
; CHECK-NEXT: movb $0, z+{{.*}}(%rip)
; CHECK-NEXT: retq
entry:
%0 = load i8, i8* @x, align 1
%tobool = trunc i8 %0 to i1
%conv = zext i1 %tobool to i32
%or = or i32 32767, %call
%neg = xor i32 %or, -1
%neg1 = xor i32 %neg, -1
%1 = load i32, i32* @y, align 4
%xor = xor i32 %neg1, %1
%or2 = or i32 %conv, %xor
%conv3 = trunc i32 %or2 to i8
%bf.load = load i24, i24* @z, align 4
%2 = zext i8 %conv3 to i24
%bf.value = and i24 %2, 4194303
store i24 %bf.value, i24* @z, align 2
ret void
}