[PATCH] D153328: [DAG] Fold (abds x, y) -> (abdu x, y) iff both args are known positive
Simon Pilgrim via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Jun 20 07:31:58 PDT 2023
This revision was automatically updated to reflect the committed changes.
Closed by commit rGff23856c1c0c: [DAG] Fold (abds x, y) -> (abdu x, y) iff both args are known positive (authored by RKSimon).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D153328/new/
https://reviews.llvm.org/D153328
Files:
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
llvm/test/CodeGen/PowerPC/vec-zext-abdu.ll
Index: llvm/test/CodeGen/PowerPC/vec-zext-abdu.ll
===================================================================
--- llvm/test/CodeGen/PowerPC/vec-zext-abdu.ll
+++ llvm/test/CodeGen/PowerPC/vec-zext-abdu.ll
@@ -20,17 +20,11 @@
; CHECK-NEXT: vperm 1, 4, 3, 1
; CHECK-NEXT: vperm 2, 4, 2, 7
; CHECK-NEXT: vperm 3, 4, 3, 7
-; CHECK-NEXT: xvnegsp 36, 38
-; CHECK-NEXT: xvnegsp 35, 35
-; CHECK-NEXT: xvnegsp 34, 34
-; CHECK-NEXT: vabsduw 2, 2, 3
-; CHECK-NEXT: xvnegsp 35, 33
-; CHECK-NEXT: vabsduw 3, 4, 3
-; CHECK-NEXT: xvnegsp 36, 37
-; CHECK-NEXT: xvnegsp 37, 32
-; CHECK-NEXT: vpkuwum 2, 2, 2
-; CHECK-NEXT: vabsduw 4, 5, 4
+; CHECK-NEXT: vabsduw 4, 5, 0
+; CHECK-NEXT: vabsduw 2, 3, 2
+; CHECK-NEXT: vabsduw 3, 1, 6
; CHECK-NEXT: vpkuwum 3, 4, 3
+; CHECK-NEXT: vpkuwum 2, 2, 2
; CHECK-NEXT: vpkuhum 2, 2, 3
; CHECK-NEXT: blr
entry:
Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5207,6 +5207,11 @@
if (N0.isUndef() || N1.isUndef())
return DAG.getConstant(0, DL, VT);
+ // fold (abds x, y) -> (abdu x, y) iff both args are known positive
+ if (Opcode == ISD::ABDS && hasOperation(ISD::ABDU, VT) &&
+ DAG.SignBitIsZero(N0) && DAG.SignBitIsZero(N1))
+ return DAG.getNode(ISD::ABDU, DL, VT, N1, N0);
+
return SDValue();
}
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