[llvm] [DAGCombiner] add fold (xor (smin(x, C), C)) and fold (xor (smax(x, C), C)) (PR #155141)
guan jian via llvm-commits
llvm-commits at lists.llvm.org
Mon Sep 15 09:19:58 PDT 2025
https://github.com/rez5427 updated https://github.com/llvm/llvm-project/pull/155141
>From 13c0f6d967accbcef8a0b1495b236faeef3a6a13 Mon Sep 17 00:00:00 2001
From: Yui5427 <785369607 at qq.com>
Date: Sun, 24 Aug 2025 13:34:01 +0800
Subject: [PATCH 01/10] [DAGCombiner] add fold (xor (smin(x, C), C)) -> select
(x < C), xor(x, C), 0
---
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 42 +++++++++++
llvm/test/CodeGen/AArch64/xor-smin-smax.ll | 75 +++++++++++++++++++
2 files changed, 117 insertions(+)
create mode 100644 llvm/test/CodeGen/AArch64/xor-smin-smax.ll
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index d130efe96b56b..80565b5d0bd7d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10092,6 +10092,48 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
if (SDValue Combined = combineCarryDiamond(DAG, TLI, N0, N1, N))
return Combined;
+ // fold (xor (smin(x, C), C)) -> select (x < C), xor(x, C), 0
+ // fold (xor (smin(C, x), C)) -> select (x < C), xor(x, C), 0
+ if (N0.getOpcode() == ISD::SMIN && N0.hasOneUse()) {
+ SDValue Op0 = N0.getOperand(0);
+ SDValue Op1 = N0.getOperand(1);
+
+ if (Op1 != N1) {
+ std::swap(Op0, Op1);
+ }
+
+ if (Op1 == N1) {
+ if (isa<ConstantSDNode>(N1)) {
+ EVT CCVT = getSetCCResultType(VT);
+ SDValue Cmp = DAG.getSetCC(SDLoc(N), CCVT, Op0, N1, ISD::SETLT);
+ SDValue XorXC = DAG.getNode(ISD::XOR, SDLoc(N), VT, Op0, N1);
+ SDValue Zero = DAG.getConstant(0, SDLoc(N), VT);
+ return DAG.getSelect(SDLoc(N), VT, Cmp, XorXC, Zero);
+ }
+ }
+ }
+
+ // fold (xor (smax(x, C), C)) -> select (x > C), xor(x, C), 0
+ // fold (xor (smax(C, x), C)) -> select (x > C), xor(x, C), 0
+ if (N0.getOpcode() == ISD::SMAX && N0.hasOneUse()) {
+ SDValue Op0 = N0.getOperand(0);
+ SDValue Op1 = N0.getOperand(1);
+
+ if (Op1 != N1) {
+ std::swap(Op0, Op1);
+ }
+
+ if (Op1 == N1) {
+ if (isa<ConstantSDNode>(N1)) {
+ EVT CCVT = getSetCCResultType(VT);
+ SDValue Cmp = DAG.getSetCC(SDLoc(N), CCVT, Op0, N1, ISD::SETGT);
+ SDValue XorXC = DAG.getNode(ISD::XOR, SDLoc(N), VT, Op0, N1);
+ SDValue Zero = DAG.getConstant(0, SDLoc(N), VT);
+ return DAG.getSelect(SDLoc(N), VT, Cmp, XorXC, Zero);
+ }
+ }
+ }
+
return SDValue();
}
diff --git a/llvm/test/CodeGen/AArch64/xor-smin-smax.ll b/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
new file mode 100644
index 0000000000000..cfdec2da61c7a
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
@@ -0,0 +1,75 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=aarch64-unknown-unknown | FileCheck %s
+
+; Test for DAGCombiner optimization: fold (xor (smin(x, C), C)) -> select (x < C), xor (x, C), 0
+
+define i64 @test_smin_neg_one(i64 %a) {
+; CHECK-LABEL: test_smin_neg_one:
+; CHECK: // %bb.0:
+; CHECK-NEXT: cmn x0, #1
+; CHECK-NEXT: csinv x0, xzr, x0, ge
+; CHECK-NEXT: ret
+ %1 = tail call i64 @llvm.smin.i64(i64 %a, i64 -1)
+ %retval.0 = xor i64 %1, -1
+ ret i64 %retval.0
+}
+
+define i64 @test_smin_zero(i64 %a) {
+; CHECK-LABEL: test_smin_zero:
+; CHECK: // %bb.0:
+; CHECK-NEXT: and x0, x0, x0, asr #63
+; CHECK-NEXT: ret
+ %1 = tail call i64 @llvm.smin.i64(i64 %a, i64 0)
+ %retval.0 = xor i64 %1, 0
+ ret i64 %retval.0
+}
+
+define i64 @test_smin_constant(i64 %a) {
+; CHECK-LABEL: test_smin_constant:
+; CHECK: // %bb.0:
+; CHECK-NEXT: eor x8, x0, #0x8
+; CHECK-NEXT: cmp x0, #8
+; CHECK-NEXT: csel x0, x8, xzr, lt
+; CHECK-NEXT: ret
+ %1 = tail call i64 @llvm.smin.i64(i64 %a, i64 8)
+ %retval.0 = xor i64 %1, 8
+ ret i64 %retval.0
+}
+
+; Test for DAGCombiner optimization: fold (xor (smax(x, C), C)) -> select (x > C), xor (x, C), 0
+
+define i64 @test_smax_neg_one(i64 %a) {
+; CHECK-LABEL: test_smax_neg_one:
+; CHECK: // %bb.0:
+; CHECK-NEXT: mvn x8, x0
+; CHECK-NEXT: bic x0, x8, x0, asr #63
+; CHECK-NEXT: ret
+ %1 = tail call i64 @llvm.smax.i64(i64 %a, i64 -1)
+ %retval.0 = xor i64 %1, -1
+ ret i64 %retval.0
+}
+
+define i64 @test_smax_zero(i64 %a) {
+; CHECK-LABEL: test_smax_zero:
+; CHECK: // %bb.0:
+; CHECK-NEXT: bic x0, x0, x0, asr #63
+; CHECK-NEXT: ret
+ %1 = tail call i64 @llvm.smax.i64(i64 %a, i64 0)
+ %retval.0 = xor i64 %1, 0
+ ret i64 %retval.0
+}
+
+define i64 @test_smax_constant(i64 %a) {
+; CHECK-LABEL: test_smax_constant:
+; CHECK: // %bb.0:
+; CHECK-NEXT: eor x8, x0, #0x8
+; CHECK-NEXT: cmp x0, #8
+; CHECK-NEXT: csel x0, x8, xzr, gt
+; CHECK-NEXT: ret
+ %1 = tail call i64 @llvm.smax.i64(i64 %a, i64 8)
+ %retval.0 = xor i64 %1, 8
+ ret i64 %retval.0
+}
+
+declare i64 @llvm.smin.i64(i64, i64)
+declare i64 @llvm.smax.i64(i64, i64)
\ No newline at end of file
>From b83f0f90692d6ddb90245fa88459be0fb2036800 Mon Sep 17 00:00:00 2001
From: Yui5427 <785369607 at qq.com>
Date: Mon, 25 Aug 2025 21:42:42 +0800
Subject: [PATCH 02/10] Combining umax umin, smin, smax
---
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 59 ++---
llvm/test/CodeGen/AArch64/xor-smin-smax.ll | 205 +++++++++++++++++-
2 files changed, 235 insertions(+), 29 deletions(-)
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 80565b5d0bd7d..e8c404f2b471d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10093,40 +10093,43 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
return Combined;
// fold (xor (smin(x, C), C)) -> select (x < C), xor(x, C), 0
- // fold (xor (smin(C, x), C)) -> select (x < C), xor(x, C), 0
- if (N0.getOpcode() == ISD::SMIN && N0.hasOneUse()) {
- SDValue Op0 = N0.getOperand(0);
- SDValue Op1 = N0.getOperand(1);
-
- if (Op1 != N1) {
- std::swap(Op0, Op1);
- }
-
- if (Op1 == N1) {
- if (isa<ConstantSDNode>(N1)) {
- EVT CCVT = getSetCCResultType(VT);
- SDValue Cmp = DAG.getSetCC(SDLoc(N), CCVT, Op0, N1, ISD::SETLT);
- SDValue XorXC = DAG.getNode(ISD::XOR, SDLoc(N), VT, Op0, N1);
- SDValue Zero = DAG.getConstant(0, SDLoc(N), VT);
- return DAG.getSelect(SDLoc(N), VT, Cmp, XorXC, Zero);
- }
- }
- }
-
// fold (xor (smax(x, C), C)) -> select (x > C), xor(x, C), 0
- // fold (xor (smax(C, x), C)) -> select (x > C), xor(x, C), 0
- if (N0.getOpcode() == ISD::SMAX && N0.hasOneUse()) {
+ // fold (xor (umin(x, C), C)) -> select (x < C), xor(x, C), 0
+ // fold (xor (umax(x, C), C)) -> select (x > C), xor(x, C), 0
+ if ((N0.getOpcode() == ISD::SMIN || N0.getOpcode() == ISD::SMAX ||
+ N0.getOpcode() == ISD::UMIN || N0.getOpcode() == ISD::UMAX) &&
+ N0.hasOneUse()) {
SDValue Op0 = N0.getOperand(0);
SDValue Op1 = N0.getOperand(1);
- if (Op1 != N1) {
- std::swap(Op0, Op1);
- }
-
if (Op1 == N1) {
- if (isa<ConstantSDNode>(N1)) {
+ if (isa<ConstantSDNode>(N1) ||
+ ISD::isBuildVectorOfConstantSDNodes(N1.getNode())) {
+ // For vectors, only optimize when the constant is zero or all-ones to
+ // avoid generating more instructions
+ if (VT.isVector()) {
+ ConstantSDNode *N1C = isConstOrConstSplat(N1);
+ if (!N1C || (!N1C->isZero() && !N1C->isAllOnes()))
+ return SDValue();
+ }
+
EVT CCVT = getSetCCResultType(VT);
- SDValue Cmp = DAG.getSetCC(SDLoc(N), CCVT, Op0, N1, ISD::SETGT);
+ ISD::CondCode CC;
+ switch (N0.getOpcode()) {
+ case ISD::SMIN:
+ CC = ISD::SETLT;
+ break;
+ case ISD::SMAX:
+ CC = ISD::SETGT;
+ break;
+ case ISD::UMIN:
+ CC = ISD::SETULT;
+ break;
+ case ISD::UMAX:
+ CC = ISD::SETUGT;
+ break;
+ }
+ SDValue Cmp = DAG.getSetCC(SDLoc(N), CCVT, Op0, N1, CC);
SDValue XorXC = DAG.getNode(ISD::XOR, SDLoc(N), VT, Op0, N1);
SDValue Zero = DAG.getConstant(0, SDLoc(N), VT);
return DAG.getSelect(SDLoc(N), VT, Cmp, XorXC, Zero);
diff --git a/llvm/test/CodeGen/AArch64/xor-smin-smax.ll b/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
index cfdec2da61c7a..74d80eeaefd4a 100644
--- a/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
+++ b/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
@@ -71,5 +71,208 @@ define i64 @test_smax_constant(i64 %a) {
ret i64 %retval.0
}
+define i64 @test_umin_neg_one(i64 %a) {
+; CHECK-LABEL: test_umin_neg_one:
+; CHECK: // %bb.0:
+; CHECK-NEXT: mvn x0, x0
+; CHECK-NEXT: ret
+ %1 = tail call i64 @llvm.umin.i64(i64 %a, i64 -1)
+ %retval.0 = xor i64 %1, -1
+ ret i64 %retval.0
+}
+
+define i64 @test_umin_zero(i64 %a) {
+; CHECK-LABEL: test_umin_zero:
+; CHECK: // %bb.0:
+; CHECK-NEXT: mov x0, xzr
+; CHECK-NEXT: ret
+ %1 = tail call i64 @llvm.umin.i64(i64 %a, i64 0)
+ %retval.0 = xor i64 %1, 0
+ ret i64 %retval.0
+}
+
+define i64 @test_umin_constant(i64 %a) {
+; CHECK-LABEL: test_umin_constant:
+; CHECK: // %bb.0:
+; CHECK-NEXT: eor x8, x0, #0x8
+; CHECK-NEXT: cmp x0, #8
+; CHECK-NEXT: csel x0, x8, xzr, lo
+; CHECK-NEXT: ret
+ %1 = tail call i64 @llvm.umin.i64(i64 %a, i64 8)
+ %retval.0 = xor i64 %1, 8
+ ret i64 %retval.0
+}
+
+define i64 @test_umax_neg_one(i64 %a) {
+; CHECK-LABEL: test_umax_neg_one:
+; CHECK: // %bb.0:
+; CHECK-NEXT: mov x0, xzr
+; CHECK-NEXT: ret
+ %1 = tail call i64 @llvm.umax.i64(i64 %a, i64 -1)
+ %retval.0 = xor i64 %1, -1
+ ret i64 %retval.0
+}
+
+define i64 @test_umax_zero(i64 %a) {
+; CHECK-LABEL: test_umax_zero:
+; CHECK: // %bb.0:
+; CHECK-NEXT: ret
+ %1 = tail call i64 @llvm.umax.i64(i64 %a, i64 0)
+ %retval.0 = xor i64 %1, 0
+ ret i64 %retval.0
+}
+
+define i64 @test_umax_constant(i64 %a) {
+; CHECK-LABEL: test_umax_constant:
+; CHECK: // %bb.0:
+; CHECK-NEXT: eor x8, x0, #0x8
+; CHECK-NEXT: cmp x0, #8
+; CHECK-NEXT: csel x0, x8, xzr, hi
+; CHECK-NEXT: ret
+ %1 = tail call i64 @llvm.umax.i64(i64 %a, i64 8)
+ %retval.0 = xor i64 %1, 8
+ ret i64 %retval.0
+}
+
+; Test vector cases
+
+define <4 x i32> @test_smin_vector_neg_one(<4 x i32> %a) {
+; CHECK-LABEL: test_smin_vector_neg_one:
+; CHECK: // %bb.0:
+; CHECK-NEXT: movi v1.2d, #0xffffffffffffffff
+; CHECK-NEXT: cmgt v1.4s, v1.4s, v0.4s
+; CHECK-NEXT: bic v0.16b, v1.16b, v0.16b
+; CHECK-NEXT: ret
+ %1 = tail call <4 x i32> @llvm.smin.v4i32(<4 x i32> %a, <4 x i32> <i32 -1, i32 -1, i32 -1, i32 -1>)
+ %retval.0 = xor <4 x i32> %1, <i32 -1, i32 -1, i32 -1, i32 -1>
+ ret <4 x i32> %retval.0
+}
+
+define <4 x i32> @test_smin_vector_zero(<4 x i32> %a) {
+; CHECK-LABEL: test_smin_vector_zero:
+; CHECK: // %bb.0:
+; CHECK-NEXT: movi v1.2d, #0000000000000000
+; CHECK-NEXT: smin v0.4s, v0.4s, v1.4s
+; CHECK-NEXT: ret
+ %1 = tail call <4 x i32> @llvm.smin.v4i32(<4 x i32> %a, <4 x i32> <i32 0, i32 0, i32 0, i32 0>)
+ %retval.0 = xor <4 x i32> %1, <i32 0, i32 0, i32 0, i32 0>
+ ret <4 x i32> %retval.0
+}
+
+define <4 x i32> @test_smin_vector_constant(<4 x i32> %a) {
+; CHECK-LABEL: test_smin_vector_constant:
+; CHECK: // %bb.0:
+; CHECK-NEXT: movi v1.4s, #8
+; CHECK-NEXT: smin v0.4s, v0.4s, v1.4s
+; CHECK-NEXT: eor v0.16b, v0.16b, v1.16b
+; CHECK-NEXT: ret
+ %1 = tail call <4 x i32> @llvm.smin.v4i32(<4 x i32> %a, <4 x i32> <i32 8, i32 8, i32 8, i32 8>)
+ %retval.0 = xor <4 x i32> %1, <i32 8, i32 8, i32 8, i32 8>
+ ret <4 x i32> %retval.0
+}
+
+define <4 x i32> @test_smax_vector_neg_one(<4 x i32> %a) {
+; CHECK-LABEL: test_smax_vector_neg_one:
+; CHECK: // %bb.0:
+; CHECK-NEXT: cmge v1.4s, v0.4s, #0
+; CHECK-NEXT: bic v0.16b, v1.16b, v0.16b
+; CHECK-NEXT: ret
+ %1 = tail call <4 x i32> @llvm.smax.v4i32(<4 x i32> %a, <4 x i32> <i32 -1, i32 -1, i32 -1, i32 -1>)
+ %retval.0 = xor <4 x i32> %1, <i32 -1, i32 -1, i32 -1, i32 -1>
+ ret <4 x i32> %retval.0
+}
+
+define <4 x i32> @test_smax_vector_zero(<4 x i32> %a) {
+; CHECK-LABEL: test_smax_vector_zero:
+; CHECK: // %bb.0:
+; CHECK-NEXT: movi v1.2d, #0000000000000000
+; CHECK-NEXT: smax v0.4s, v0.4s, v1.4s
+; CHECK-NEXT: ret
+ %1 = tail call <4 x i32> @llvm.smax.v4i32(<4 x i32> %a, <4 x i32> <i32 0, i32 0, i32 0, i32 0>)
+ %retval.0 = xor <4 x i32> %1, <i32 0, i32 0, i32 0, i32 0>
+ ret <4 x i32> %retval.0
+}
+
+define <4 x i32> @test_smax_vector_constant(<4 x i32> %a) {
+; CHECK-LABEL: test_smax_vector_constant:
+; CHECK: // %bb.0:
+; CHECK-NEXT: movi v1.4s, #8
+; CHECK-NEXT: smax v0.4s, v0.4s, v1.4s
+; CHECK-NEXT: eor v0.16b, v0.16b, v1.16b
+; CHECK-NEXT: ret
+ %1 = tail call <4 x i32> @llvm.smax.v4i32(<4 x i32> %a, <4 x i32> <i32 8, i32 8, i32 8, i32 8>)
+ %retval.0 = xor <4 x i32> %1, <i32 8, i32 8, i32 8, i32 8>
+ ret <4 x i32> %retval.0
+}
+
+define <4 x i32> @test_umin_vector_neg_one(<4 x i32> %a) {
+; CHECK-LABEL: test_umin_vector_neg_one:
+; CHECK: // %bb.0:
+; CHECK-NEXT: mvn v0.16b, v0.16b
+; CHECK-NEXT: ret
+ %1 = tail call <4 x i32> @llvm.umin.v4i32(<4 x i32> %a, <4 x i32> <i32 -1, i32 -1, i32 -1, i32 -1>)
+ %retval.0 = xor <4 x i32> %1, <i32 -1, i32 -1, i32 -1, i32 -1>
+ ret <4 x i32> %retval.0
+}
+
+define <4 x i32> @test_umin_vector_zero(<4 x i32> %a) {
+; CHECK-LABEL: test_umin_vector_zero:
+; CHECK: // %bb.0:
+; CHECK-NEXT: movi v0.2d, #0000000000000000
+; CHECK-NEXT: ret
+ %1 = tail call <4 x i32> @llvm.umin.v4i32(<4 x i32> %a, <4 x i32> <i32 0, i32 0, i32 0, i32 0>)
+ %retval.0 = xor <4 x i32> %1, <i32 0, i32 0, i32 0, i32 0>
+ ret <4 x i32> %retval.0
+}
+
+define <4 x i32> @test_umin_vector_constant(<4 x i32> %a) {
+; CHECK-LABEL: test_umin_vector_constant:
+; CHECK: // %bb.0:
+; CHECK-NEXT: movi v1.4s, #8
+; CHECK-NEXT: umin v0.4s, v0.4s, v1.4s
+; CHECK-NEXT: eor v0.16b, v0.16b, v1.16b
+; CHECK-NEXT: ret
+ %1 = tail call <4 x i32> @llvm.umin.v4i32(<4 x i32> %a, <4 x i32> <i32 8, i32 8, i32 8, i32 8>)
+ %retval.0 = xor <4 x i32> %1, <i32 8, i32 8, i32 8, i32 8>
+ ret <4 x i32> %retval.0
+}
+
+define <4 x i32> @test_umax_vector_neg_one(<4 x i32> %a) {
+; CHECK-LABEL: test_umax_vector_neg_one:
+; CHECK: // %bb.0:
+; CHECK-NEXT: movi v0.2d, #0000000000000000
+; CHECK-NEXT: ret
+ %1 = tail call <4 x i32> @llvm.umax.v4i32(<4 x i32> %a, <4 x i32> <i32 -1, i32 -1, i32 -1, i32 -1>)
+ %retval.0 = xor <4 x i32> %1, <i32 -1, i32 -1, i32 -1, i32 -1>
+ ret <4 x i32> %retval.0
+}
+
+define <4 x i32> @test_umax_vector_zero(<4 x i32> %a) {
+; CHECK-LABEL: test_umax_vector_zero:
+; CHECK: // %bb.0:
+; CHECK-NEXT: ret
+ %1 = tail call <4 x i32> @llvm.umax.v4i32(<4 x i32> %a, <4 x i32> <i32 0, i32 0, i32 0, i32 0>)
+ %retval.0 = xor <4 x i32> %1, <i32 0, i32 0, i32 0, i32 0>
+ ret <4 x i32> %retval.0
+}
+
+define <4 x i32> @test_umax_vector_constant(<4 x i32> %a) {
+; CHECK-LABEL: test_umax_vector_constant:
+; CHECK: // %bb.0:
+; CHECK-NEXT: movi v1.4s, #8
+; CHECK-NEXT: umax v0.4s, v0.4s, v1.4s
+; CHECK-NEXT: eor v0.16b, v0.16b, v1.16b
+; CHECK-NEXT: ret
+ %1 = tail call <4 x i32> @llvm.umax.v4i32(<4 x i32> %a, <4 x i32> <i32 8, i32 8, i32 8, i32 8>)
+ %retval.0 = xor <4 x i32> %1, <i32 8, i32 8, i32 8, i32 8>
+ ret <4 x i32> %retval.0
+}
+
declare i64 @llvm.smin.i64(i64, i64)
-declare i64 @llvm.smax.i64(i64, i64)
\ No newline at end of file
+declare i64 @llvm.smax.i64(i64, i64)
+declare i64 @llvm.umin.i64(i64, i64)
+declare i64 @llvm.umax.i64(i64, i64)
+declare <4 x i32> @llvm.smin.v4i32(<4 x i32>, <4 x i32>)
+declare <4 x i32> @llvm.smax.v4i32(<4 x i32>, <4 x i32>)
+declare <4 x i32> @llvm.umin.v4i32(<4 x i32>, <4 x i32>)
+declare <4 x i32> @llvm.umax.v4i32(<4 x i32>, <4 x i32>)
\ No newline at end of file
>From 841ae7ca9ebe91ad89826661929acf9aa050fe2c Mon Sep 17 00:00:00 2001
From: Yui5427 <785369607 at qq.com>
Date: Wed, 27 Aug 2025 18:10:36 +0800
Subject: [PATCH 03/10] Use sd_match
---
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index e8c404f2b471d..05f25b199389e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10096,11 +10096,11 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
// fold (xor (smax(x, C), C)) -> select (x > C), xor(x, C), 0
// fold (xor (umin(x, C), C)) -> select (x < C), xor(x, C), 0
// fold (xor (umax(x, C), C)) -> select (x > C), xor(x, C), 0
- if ((N0.getOpcode() == ISD::SMIN || N0.getOpcode() == ISD::SMAX ||
- N0.getOpcode() == ISD::UMIN || N0.getOpcode() == ISD::UMAX) &&
- N0.hasOneUse()) {
- SDValue Op0 = N0.getOperand(0);
- SDValue Op1 = N0.getOperand(1);
+ SDValue Op0, Op1;
+ if ((sd_match(N0, m_OneUse(m_AnyOf(m_SMin(m_Value(Op0), m_Value(Op1)),
+ m_SMax(m_Value(Op0), m_Value(Op1)),
+ m_UMin(m_Value(Op0), m_Value(Op1)),
+ m_UMax(m_Value(Op0), m_Value(Op1))))))) {
if (Op1 == N1) {
if (isa<ConstantSDNode>(N1) ||
>From 7e1effab1635ed9341cc57ba6a0ca2d4bf40e706 Mon Sep 17 00:00:00 2001
From: Yui5427 <785369607 at qq.com>
Date: Wed, 27 Aug 2025 22:08:37 +0800
Subject: [PATCH 04/10] Use m_specific and DL
---
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 70 +++++++++----------
1 file changed, 34 insertions(+), 36 deletions(-)
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 05f25b199389e..c401841c8c21b 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10096,44 +10096,42 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
// fold (xor (smax(x, C), C)) -> select (x > C), xor(x, C), 0
// fold (xor (umin(x, C), C)) -> select (x < C), xor(x, C), 0
// fold (xor (umax(x, C), C)) -> select (x > C), xor(x, C), 0
- SDValue Op0, Op1;
- if ((sd_match(N0, m_OneUse(m_AnyOf(m_SMin(m_Value(Op0), m_Value(Op1)),
- m_SMax(m_Value(Op0), m_Value(Op1)),
- m_UMin(m_Value(Op0), m_Value(Op1)),
- m_UMax(m_Value(Op0), m_Value(Op1))))))) {
-
- if (Op1 == N1) {
- if (isa<ConstantSDNode>(N1) ||
- ISD::isBuildVectorOfConstantSDNodes(N1.getNode())) {
- // For vectors, only optimize when the constant is zero or all-ones to
- // avoid generating more instructions
- if (VT.isVector()) {
- ConstantSDNode *N1C = isConstOrConstSplat(N1);
- if (!N1C || (!N1C->isZero() && !N1C->isAllOnes()))
- return SDValue();
- }
+ SDValue Op0;
+ if ((sd_match(N0, m_OneUse(m_AnyOf(m_SMin(m_Value(Op0), m_Specific(N1)),
+ m_SMax(m_Value(Op0), m_Specific(N1)),
+ m_UMin(m_Value(Op0), m_Specific(N1)),
+ m_UMax(m_Value(Op0), m_Specific(N1))))))) {
+
+ if (isa<ConstantSDNode>(N1) ||
+ ISD::isBuildVectorOfConstantSDNodes(N1.getNode())) {
+ // For vectors, only optimize when the constant is zero or all-ones to
+ // avoid generating more instructions
+ if (VT.isVector()) {
+ ConstantSDNode *N1C = isConstOrConstSplat(N1);
+ if (!N1C || (!N1C->isZero() && !N1C->isAllOnes()))
+ return SDValue();
+ }
- EVT CCVT = getSetCCResultType(VT);
- ISD::CondCode CC;
- switch (N0.getOpcode()) {
- case ISD::SMIN:
- CC = ISD::SETLT;
- break;
- case ISD::SMAX:
- CC = ISD::SETGT;
- break;
- case ISD::UMIN:
- CC = ISD::SETULT;
- break;
- case ISD::UMAX:
- CC = ISD::SETUGT;
- break;
- }
- SDValue Cmp = DAG.getSetCC(SDLoc(N), CCVT, Op0, N1, CC);
- SDValue XorXC = DAG.getNode(ISD::XOR, SDLoc(N), VT, Op0, N1);
- SDValue Zero = DAG.getConstant(0, SDLoc(N), VT);
- return DAG.getSelect(SDLoc(N), VT, Cmp, XorXC, Zero);
+ EVT CCVT = getSetCCResultType(VT);
+ ISD::CondCode CC;
+ switch (N0.getOpcode()) {
+ case ISD::SMIN:
+ CC = ISD::SETLT;
+ break;
+ case ISD::SMAX:
+ CC = ISD::SETGT;
+ break;
+ case ISD::UMIN:
+ CC = ISD::SETULT;
+ break;
+ case ISD::UMAX:
+ CC = ISD::SETUGT;
+ break;
}
+ SDValue Cmp = DAG.getSetCC(DL, CCVT, Op0, N1, CC);
+ SDValue XorXC = DAG.getNode(ISD::XOR, DL, VT, Op0, N1);
+ SDValue Zero = DAG.getConstant(0, DL, VT);
+ return DAG.getSelect(DL, VT, Cmp, XorXC, Zero);
}
}
>From a3a1b2b9309f0aee9de16a6fc1f2263ad1b1b7d6 Mon Sep 17 00:00:00 2001
From: guan jian <148229859+rez5427 at users.noreply.github.com>
Date: Thu, 28 Aug 2025 00:09:25 +0800
Subject: [PATCH 05/10] Update llvm/test/CodeGen/AArch64/xor-smin-smax.ll
Co-authored-by: Matt Arsenault <arsenm2 at gmail.com>
---
llvm/test/CodeGen/AArch64/xor-smin-smax.ll | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/llvm/test/CodeGen/AArch64/xor-smin-smax.ll b/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
index 74d80eeaefd4a..904397a23afd1 100644
--- a/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
+++ b/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
@@ -275,4 +275,4 @@ declare i64 @llvm.umax.i64(i64, i64)
declare <4 x i32> @llvm.smin.v4i32(<4 x i32>, <4 x i32>)
declare <4 x i32> @llvm.smax.v4i32(<4 x i32>, <4 x i32>)
declare <4 x i32> @llvm.umin.v4i32(<4 x i32>, <4 x i32>)
-declare <4 x i32> @llvm.umax.v4i32(<4 x i32>, <4 x i32>)
\ No newline at end of file
+declare <4 x i32> @llvm.umax.v4i32(<4 x i32>, <4 x i32>)
>From 8fe2c394cb93683ab7c91e4849d3931153d7ee9d Mon Sep 17 00:00:00 2001
From: Yui5427 <785369607 at qq.com>
Date: Fri, 29 Aug 2025 20:48:32 +0800
Subject: [PATCH 06/10] Use freeze N1
---
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index c401841c8c21b..72ab54cc7220f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10128,8 +10128,9 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
CC = ISD::SETUGT;
break;
}
- SDValue Cmp = DAG.getSetCC(DL, CCVT, Op0, N1, CC);
- SDValue XorXC = DAG.getNode(ISD::XOR, DL, VT, Op0, N1);
+ SDValue FN1 = DAG.getFreeze(N1);
+ SDValue Cmp = DAG.getSetCC(DL, CCVT, Op0, FN1, CC);
+ SDValue XorXC = DAG.getNode(ISD::XOR, DL, VT, Op0, FN1);
SDValue Zero = DAG.getConstant(0, DL, VT);
return DAG.getSelect(DL, VT, Cmp, XorXC, Zero);
}
>From baae52b8a8d43b7d80b28cdcb388768100cbd4cf Mon Sep 17 00:00:00 2001
From: Yui5427 <785369607 at qq.com>
Date: Thu, 4 Sep 2025 20:47:41 +0800
Subject: [PATCH 07/10] remove redundent bracket
---
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 72ab54cc7220f..54e05cf1cb352 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10097,10 +10097,10 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
// fold (xor (umin(x, C), C)) -> select (x < C), xor(x, C), 0
// fold (xor (umax(x, C), C)) -> select (x > C), xor(x, C), 0
SDValue Op0;
- if ((sd_match(N0, m_OneUse(m_AnyOf(m_SMin(m_Value(Op0), m_Specific(N1)),
- m_SMax(m_Value(Op0), m_Specific(N1)),
- m_UMin(m_Value(Op0), m_Specific(N1)),
- m_UMax(m_Value(Op0), m_Specific(N1))))))) {
+ if (sd_match(N0, m_OneUse(m_AnyOf(m_SMin(m_Value(Op0), m_Specific(N1)),
+ m_SMax(m_Value(Op0), m_Specific(N1)),
+ m_UMin(m_Value(Op0), m_Specific(N1)),
+ m_UMax(m_Value(Op0), m_Specific(N1)))))) {
if (isa<ConstantSDNode>(N1) ||
ISD::isBuildVectorOfConstantSDNodes(N1.getNode())) {
>From 9d5885b90a6953413d2dd3d5ce44ba4df82b8ece Mon Sep 17 00:00:00 2001
From: rez5427 <guanjian at stu.cdut.edu.cn>
Date: Mon, 8 Sep 2025 01:19:28 +0800
Subject: [PATCH 08/10] Add legal
---
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 5 +++++
llvm/test/CodeGen/AArch64/xor-smin-smax.ll | 6 +++---
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 54e05cf1cb352..4b20b756f8a15 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10112,6 +10112,11 @@ SDValue DAGCombiner::visitXOR(SDNode *N) {
return SDValue();
}
+ // Avoid the fold if the minmax operation is legal and select is expensive
+ if (TLI.isOperationLegal(N0.getOpcode(), VT) &&
+ TLI.isPredictableSelectExpensive())
+ return SDValue();
+
EVT CCVT = getSetCCResultType(VT);
ISD::CondCode CC;
switch (N0.getOpcode()) {
diff --git a/llvm/test/CodeGen/AArch64/xor-smin-smax.ll b/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
index 904397a23afd1..012a2094f8197 100644
--- a/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
+++ b/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
@@ -1,5 +1,5 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc < %s -mtriple=aarch64-unknown-unknown | FileCheck %s
+; RUN: llc < %s -mtriple=aarch64-unknown-unknown -mcpu=cortex-a53 | FileCheck %s
; Test for DAGCombiner optimization: fold (xor (smin(x, C), C)) -> select (x < C), xor (x, C), 0
@@ -141,7 +141,7 @@ define <4 x i32> @test_smin_vector_neg_one(<4 x i32> %a) {
; CHECK: // %bb.0:
; CHECK-NEXT: movi v1.2d, #0xffffffffffffffff
; CHECK-NEXT: cmgt v1.4s, v1.4s, v0.4s
-; CHECK-NEXT: bic v0.16b, v1.16b, v0.16b
+; CHECK-NEXT: bic v0.16b, v1.16b, v0.16b
; CHECK-NEXT: ret
%1 = tail call <4 x i32> @llvm.smin.v4i32(<4 x i32> %a, <4 x i32> <i32 -1, i32 -1, i32 -1, i32 -1>)
%retval.0 = xor <4 x i32> %1, <i32 -1, i32 -1, i32 -1, i32 -1>
@@ -175,7 +175,7 @@ define <4 x i32> @test_smax_vector_neg_one(<4 x i32> %a) {
; CHECK-LABEL: test_smax_vector_neg_one:
; CHECK: // %bb.0:
; CHECK-NEXT: cmge v1.4s, v0.4s, #0
-; CHECK-NEXT: bic v0.16b, v1.16b, v0.16b
+; CHECK-NEXT: bic v0.16b, v1.16b, v0.16b
; CHECK-NEXT: ret
%1 = tail call <4 x i32> @llvm.smax.v4i32(<4 x i32> %a, <4 x i32> <i32 -1, i32 -1, i32 -1, i32 -1>)
%retval.0 = xor <4 x i32> %1, <i32 -1, i32 -1, i32 -1, i32 -1>
>From 1fe7fd5e8f126549d7db20b5a2f6cf78a48c1c0d Mon Sep 17 00:00:00 2001
From: rez5427 <guanjian at stu.cdut.edu.cn>
Date: Mon, 8 Sep 2025 22:25:50 +0800
Subject: [PATCH 09/10] remove constant zero tests
---
llvm/test/CodeGen/AArch64/xor-smin-smax.ll | 82 ----------------------
1 file changed, 82 deletions(-)
diff --git a/llvm/test/CodeGen/AArch64/xor-smin-smax.ll b/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
index 012a2094f8197..2d6696e1c556e 100644
--- a/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
+++ b/llvm/test/CodeGen/AArch64/xor-smin-smax.ll
@@ -14,16 +14,6 @@ define i64 @test_smin_neg_one(i64 %a) {
ret i64 %retval.0
}
-define i64 @test_smin_zero(i64 %a) {
-; CHECK-LABEL: test_smin_zero:
-; CHECK: // %bb.0:
-; CHECK-NEXT: and x0, x0, x0, asr #63
-; CHECK-NEXT: ret
- %1 = tail call i64 @llvm.smin.i64(i64 %a, i64 0)
- %retval.0 = xor i64 %1, 0
- ret i64 %retval.0
-}
-
define i64 @test_smin_constant(i64 %a) {
; CHECK-LABEL: test_smin_constant:
; CHECK: // %bb.0:
@@ -37,7 +27,6 @@ define i64 @test_smin_constant(i64 %a) {
}
; Test for DAGCombiner optimization: fold (xor (smax(x, C), C)) -> select (x > C), xor (x, C), 0
-
define i64 @test_smax_neg_one(i64 %a) {
; CHECK-LABEL: test_smax_neg_one:
; CHECK: // %bb.0:
@@ -49,16 +38,6 @@ define i64 @test_smax_neg_one(i64 %a) {
ret i64 %retval.0
}
-define i64 @test_smax_zero(i64 %a) {
-; CHECK-LABEL: test_smax_zero:
-; CHECK: // %bb.0:
-; CHECK-NEXT: bic x0, x0, x0, asr #63
-; CHECK-NEXT: ret
- %1 = tail call i64 @llvm.smax.i64(i64 %a, i64 0)
- %retval.0 = xor i64 %1, 0
- ret i64 %retval.0
-}
-
define i64 @test_smax_constant(i64 %a) {
; CHECK-LABEL: test_smax_constant:
; CHECK: // %bb.0:
@@ -81,16 +60,6 @@ define i64 @test_umin_neg_one(i64 %a) {
ret i64 %retval.0
}
-define i64 @test_umin_zero(i64 %a) {
-; CHECK-LABEL: test_umin_zero:
-; CHECK: // %bb.0:
-; CHECK-NEXT: mov x0, xzr
-; CHECK-NEXT: ret
- %1 = tail call i64 @llvm.umin.i64(i64 %a, i64 0)
- %retval.0 = xor i64 %1, 0
- ret i64 %retval.0
-}
-
define i64 @test_umin_constant(i64 %a) {
; CHECK-LABEL: test_umin_constant:
; CHECK: // %bb.0:
@@ -113,15 +82,6 @@ define i64 @test_umax_neg_one(i64 %a) {
ret i64 %retval.0
}
-define i64 @test_umax_zero(i64 %a) {
-; CHECK-LABEL: test_umax_zero:
-; CHECK: // %bb.0:
-; CHECK-NEXT: ret
- %1 = tail call i64 @llvm.umax.i64(i64 %a, i64 0)
- %retval.0 = xor i64 %1, 0
- ret i64 %retval.0
-}
-
define i64 @test_umax_constant(i64 %a) {
; CHECK-LABEL: test_umax_constant:
; CHECK: // %bb.0:
@@ -135,7 +95,6 @@ define i64 @test_umax_constant(i64 %a) {
}
; Test vector cases
-
define <4 x i32> @test_smin_vector_neg_one(<4 x i32> %a) {
; CHECK-LABEL: test_smin_vector_neg_one:
; CHECK: // %bb.0:
@@ -148,17 +107,6 @@ define <4 x i32> @test_smin_vector_neg_one(<4 x i32> %a) {
ret <4 x i32> %retval.0
}
-define <4 x i32> @test_smin_vector_zero(<4 x i32> %a) {
-; CHECK-LABEL: test_smin_vector_zero:
-; CHECK: // %bb.0:
-; CHECK-NEXT: movi v1.2d, #0000000000000000
-; CHECK-NEXT: smin v0.4s, v0.4s, v1.4s
-; CHECK-NEXT: ret
- %1 = tail call <4 x i32> @llvm.smin.v4i32(<4 x i32> %a, <4 x i32> <i32 0, i32 0, i32 0, i32 0>)
- %retval.0 = xor <4 x i32> %1, <i32 0, i32 0, i32 0, i32 0>
- ret <4 x i32> %retval.0
-}
-
define <4 x i32> @test_smin_vector_constant(<4 x i32> %a) {
; CHECK-LABEL: test_smin_vector_constant:
; CHECK: // %bb.0:
@@ -182,17 +130,6 @@ define <4 x i32> @test_smax_vector_neg_one(<4 x i32> %a) {
ret <4 x i32> %retval.0
}
-define <4 x i32> @test_smax_vector_zero(<4 x i32> %a) {
-; CHECK-LABEL: test_smax_vector_zero:
-; CHECK: // %bb.0:
-; CHECK-NEXT: movi v1.2d, #0000000000000000
-; CHECK-NEXT: smax v0.4s, v0.4s, v1.4s
-; CHECK-NEXT: ret
- %1 = tail call <4 x i32> @llvm.smax.v4i32(<4 x i32> %a, <4 x i32> <i32 0, i32 0, i32 0, i32 0>)
- %retval.0 = xor <4 x i32> %1, <i32 0, i32 0, i32 0, i32 0>
- ret <4 x i32> %retval.0
-}
-
define <4 x i32> @test_smax_vector_constant(<4 x i32> %a) {
; CHECK-LABEL: test_smax_vector_constant:
; CHECK: // %bb.0:
@@ -215,16 +152,6 @@ define <4 x i32> @test_umin_vector_neg_one(<4 x i32> %a) {
ret <4 x i32> %retval.0
}
-define <4 x i32> @test_umin_vector_zero(<4 x i32> %a) {
-; CHECK-LABEL: test_umin_vector_zero:
-; CHECK: // %bb.0:
-; CHECK-NEXT: movi v0.2d, #0000000000000000
-; CHECK-NEXT: ret
- %1 = tail call <4 x i32> @llvm.umin.v4i32(<4 x i32> %a, <4 x i32> <i32 0, i32 0, i32 0, i32 0>)
- %retval.0 = xor <4 x i32> %1, <i32 0, i32 0, i32 0, i32 0>
- ret <4 x i32> %retval.0
-}
-
define <4 x i32> @test_umin_vector_constant(<4 x i32> %a) {
; CHECK-LABEL: test_umin_vector_constant:
; CHECK: // %bb.0:
@@ -247,15 +174,6 @@ define <4 x i32> @test_umax_vector_neg_one(<4 x i32> %a) {
ret <4 x i32> %retval.0
}
-define <4 x i32> @test_umax_vector_zero(<4 x i32> %a) {
-; CHECK-LABEL: test_umax_vector_zero:
-; CHECK: // %bb.0:
-; CHECK-NEXT: ret
- %1 = tail call <4 x i32> @llvm.umax.v4i32(<4 x i32> %a, <4 x i32> <i32 0, i32 0, i32 0, i32 0>)
- %retval.0 = xor <4 x i32> %1, <i32 0, i32 0, i32 0, i32 0>
- ret <4 x i32> %retval.0
-}
-
define <4 x i32> @test_umax_vector_constant(<4 x i32> %a) {
; CHECK-LABEL: test_umax_vector_constant:
; CHECK: // %bb.0:
>From 8793ff37cbaa6bd866e32494ba640edb5acd2afd Mon Sep 17 00:00:00 2001
From: rez5427 <guanjian at stu.cdut.edu.cn>
Date: Tue, 16 Sep 2025 00:19:38 +0800
Subject: [PATCH 10/10] rename xor-smin-smax to xor-min-max
---
llvm/test/CodeGen/AArch64/{xor-smin-smax.ll => xor-min-max.ll} | 0
1 file changed, 0 insertions(+), 0 deletions(-)
rename llvm/test/CodeGen/AArch64/{xor-smin-smax.ll => xor-min-max.ll} (100%)
diff --git a/llvm/test/CodeGen/AArch64/xor-smin-smax.ll b/llvm/test/CodeGen/AArch64/xor-min-max.ll
similarity index 100%
rename from llvm/test/CodeGen/AArch64/xor-smin-smax.ll
rename to llvm/test/CodeGen/AArch64/xor-min-max.ll
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