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[SDAG] Intersect poison-generating flags after CSE #114650

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Merged
merged 1 commit into from
Nov 2, 2024
Merged

[SDAG] Intersect poison-generating flags after CSE #114650

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8 changes: 6 additions & 2 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -10318,8 +10318,10 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
AddNodeIDNode(ID, Opcode, VTs, Ops);
void *IP = nullptr;

if (SDNode *E = FindNodeOrInsertPos(ID, DL, IP))
if (SDNode *E = FindNodeOrInsertPos(ID, DL, IP)) {
E->intersectFlagsWith(Flags);
return SDValue(E, 0);
}

N = newSDNode<SDNode>(Opcode, DL.getIROrder(), DL.getDebugLoc(), VTs);
createOperands(N, Ops);
Expand Down Expand Up @@ -10524,8 +10526,10 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, SDVTList VTList,
FoldingSetNodeID ID;
AddNodeIDNode(ID, Opcode, VTList, Ops);
void *IP = nullptr;
if (SDNode *E = FindNodeOrInsertPos(ID, DL, IP))
if (SDNode *E = FindNodeOrInsertPos(ID, DL, IP)) {
E->intersectFlagsWith(Flags);
return SDValue(E, 0);
}

N = newSDNode<SDNode>(Opcode, DL.getIROrder(), DL.getDebugLoc(), VTList);
createOperands(N, Ops);
Expand Down
23 changes: 23 additions & 0 deletions llvm/test/CodeGen/ARM/dagcombine-drop-flags-freeze.ll
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@@ -0,0 +1,23 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
; RUN: llc -mtriple=arm-eabi -o - %s | FileCheck %s

; Ensure poison-generating flags are stripped by the time a freeze operand is visited.

define i1 @drop_flags(i32 noundef %numentries, i64 %cond, i64 %arg) {
; CHECK-LABEL: drop_flags:
; CHECK: @ %bb.0: @ %entry
; CHECK-NEXT: ldm sp, {r1, r12}
; CHECK-NEXT: subs r1, r2, r1
; CHECK-NEXT: sbcs r1, r3, r12
; CHECK-NEXT: movlo r0, r2
; CHECK-NEXT: rsbs r1, r0, #0
; CHECK-NEXT: adc r0, r0, r1
; CHECK-NEXT: mov pc, lr
entry:
%cmp4 = icmp samesign ult i64 %cond, %arg
%conv6 = trunc nuw i64 %cond to i32
%spec.select = select i1 %cmp4, i32 %conv6, i32 %numentries
%spec.select.fr = freeze i32 %spec.select
%cmpz = icmp eq i32 %spec.select.fr, 0
ret i1 %cmpz
}
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