[Mlir-commits] [mlir] [mlir][arith] Fold min/max ops using absorption law and redundant con… (PR #160224)
llvmlistbot at llvm.org
llvmlistbot at llvm.org
Mon Sep 22 20:20:38 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-mlir
Author: Ziliang Zhang (ziliangzl)
<details>
<summary>Changes</summary>
…secutive ops
Supported folding for arith.maxsi, arith.maxui, arith.minsi, and arith.minui.
1. Fold redundant consecutive min/max operations: max(max(a, b), b) -> max(a, b) max(max(a, b), a) -> max(a, b) max(a, max(a, b)) -> max(a, b) max(b, max(a, b)) -> max(a, b) (similar cases for min)
2. Fold using the absorption law: max(min(a, b), a) -> a max(min(b, a), a) -> a max(a, min(a, b)) -> a max(a, min(b, a)) -> a (similar cases for min)
---
Full diff: https://github.com/llvm/llvm-project/pull/160224.diff
2 Files Affected:
- (modified) mlir/lib/Dialect/Arith/IR/ArithOps.cpp (+96)
- (modified) mlir/test/Dialect/Arith/canonicalize.mlir (+136-1)
``````````diff
diff --git a/mlir/lib/Dialect/Arith/IR/ArithOps.cpp b/mlir/lib/Dialect/Arith/IR/ArithOps.cpp
index 7cfd6d3a98df8..ea95d15b96f0c 100644
--- a/mlir/lib/Dialect/Arith/IR/ArithOps.cpp
+++ b/mlir/lib/Dialect/Arith/IR/ArithOps.cpp
@@ -1156,6 +1156,30 @@ OpFoldResult MaxSIOp::fold(FoldAdaptor adaptor) {
return getLhs();
}
+ // max(max(a, b), b) -> max(a, b)
+ // max(max(a, b), a) -> max(a, b)
+ if (auto max = getLhs().getDefiningOp<MaxSIOp>())
+ if (getRhs() == max.getRhs() || getRhs() == max.getLhs())
+ return getLhs();
+
+ // max(a, max(a, b)) -> max(a, b)
+ // max(b, max(a, b)) -> max(a, b)
+ if (auto max = getRhs().getDefiningOp<MaxSIOp>())
+ if (getLhs() == max.getRhs() || getLhs() == max.getLhs())
+ return getRhs();
+
+ // max(min(a, b), a) -> a
+ // max(min(b, a), a) -> a
+ if (auto min = getLhs().getDefiningOp<MinSIOp>())
+ if (getRhs() == min.getRhs() || getRhs() == min.getLhs())
+ return getRhs();
+
+ // max(a, min(a, b)) -> a
+ // max(a, min(b, a)) -> a
+ if (auto min = getRhs().getDefiningOp<MinSIOp>())
+ if (getLhs() == min.getRhs() || getLhs() == min.getLhs())
+ return getLhs();
+
return constFoldBinaryOp<IntegerAttr>(adaptor.getOperands(),
[](const APInt &a, const APInt &b) {
return llvm::APIntOps::smax(a, b);
@@ -1181,6 +1205,30 @@ OpFoldResult MaxUIOp::fold(FoldAdaptor adaptor) {
return getLhs();
}
+ // max(max(a, b), b) -> max(a, b)
+ // max(max(a, b), a) -> max(a, b)
+ if (auto max = getLhs().getDefiningOp<MaxUIOp>())
+ if (getRhs() == max.getRhs() || getRhs() == max.getLhs())
+ return getLhs();
+
+ // max(a, max(a, b)) -> max(a, b)
+ // max(b, max(a, b)) -> max(a, b)
+ if (auto max = getRhs().getDefiningOp<MaxUIOp>())
+ if (getLhs() == max.getRhs() || getLhs() == max.getLhs())
+ return getRhs();
+
+ // max(min(a, b), a) -> a
+ // max(min(b, a), a) -> a
+ if (auto min = getLhs().getDefiningOp<MinUIOp>())
+ if (getRhs() == min.getRhs() || getRhs() == min.getLhs())
+ return getRhs();
+
+ // max(a, min(a, b)) -> a
+ // max(a, min(b, a)) -> a
+ if (auto min = getRhs().getDefiningOp<MinUIOp>())
+ if (getLhs() == min.getRhs() || getLhs() == min.getLhs())
+ return getLhs();
+
return constFoldBinaryOp<IntegerAttr>(adaptor.getOperands(),
[](const APInt &a, const APInt &b) {
return llvm::APIntOps::umax(a, b);
@@ -1242,6 +1290,30 @@ OpFoldResult MinSIOp::fold(FoldAdaptor adaptor) {
return getLhs();
}
+ // min(min(a, b), b) -> min(a, b)
+ // min(min(a, b), a) -> min(a, b)
+ if (auto min = getLhs().getDefiningOp<MinSIOp>())
+ if (getRhs() == min.getRhs() || getRhs() == min.getLhs())
+ return getLhs();
+
+ // min(a, min(a, b)) -> min(a, b)
+ // min(b, min(a, b)) -> min(a, b)
+ if (auto min = getRhs().getDefiningOp<MinSIOp>())
+ if (getLhs() == min.getRhs() || getLhs() == min.getLhs())
+ return getRhs();
+
+ // min(max(a, b), a) -> a
+ // min(max(b, a), a) -> a
+ if (auto max = getLhs().getDefiningOp<MaxSIOp>())
+ if (getRhs() == max.getRhs() || getRhs() == max.getLhs())
+ return getRhs();
+
+ // min(a, max(a, b)) -> a
+ // min(a, max(b, a)) -> a
+ if (auto max = getRhs().getDefiningOp<MaxSIOp>())
+ if (getLhs() == max.getRhs() || getLhs() == max.getLhs())
+ return getLhs();
+
return constFoldBinaryOp<IntegerAttr>(adaptor.getOperands(),
[](const APInt &a, const APInt &b) {
return llvm::APIntOps::smin(a, b);
@@ -1267,6 +1339,30 @@ OpFoldResult MinUIOp::fold(FoldAdaptor adaptor) {
return getLhs();
}
+ // min(min(a, b), b) -> min(a, b)
+ // min(min(a, b), a) -> min(a, b)
+ if (auto min = getLhs().getDefiningOp<MinUIOp>())
+ if (getRhs() == min.getRhs() || getRhs() == min.getLhs())
+ return getLhs();
+
+ // min(a, min(a, b)) -> min(a, b)
+ // min(b, min(a, b)) -> min(a, b)
+ if (auto min = getRhs().getDefiningOp<MinUIOp>())
+ if (getLhs() == min.getRhs() || getLhs() == min.getLhs())
+ return getRhs();
+
+ // min(max(a, b), a) -> a
+ // min(max(b, a), a) -> a
+ if (auto max = getLhs().getDefiningOp<MaxUIOp>())
+ if (getRhs() == max.getRhs() || getRhs() == max.getLhs())
+ return getRhs();
+
+ // min(a, max(a, b)) -> a
+ // min(a, max(b, a)) -> a
+ if (auto max = getRhs().getDefiningOp<MaxUIOp>())
+ if (getLhs() == max.getRhs() || getLhs() == max.getLhs())
+ return getLhs();
+
return constFoldBinaryOp<IntegerAttr>(adaptor.getOperands(),
[](const APInt &a, const APInt &b) {
return llvm::APIntOps::umin(a, b);
diff --git a/mlir/test/Dialect/Arith/canonicalize.mlir b/mlir/test/Dialect/Arith/canonicalize.mlir
index ca3de3a2d7703..afa53a33e79fe 100644
--- a/mlir/test/Dialect/Arith/canonicalize.mlir
+++ b/mlir/test/Dialect/Arith/canonicalize.mlir
@@ -1984,6 +1984,40 @@ func.func @test_maxsi2(%arg0 : i8) -> (i8, i8, i8, i8) {
return %0, %1, %2, %3: i8, i8, i8, i8
}
+// CHECK-LABEL: foldMaxsiMaxsi1
+// CHECK: %[[MAXSI:.*]] = arith.maxsi %arg1, %arg0 : i32
+// CHECK: return %[[MAXSI]] : i32
+func.func public @foldMaxsiMaxsi1(%arg0: i32, %arg1: i32) -> i32 {
+ %max1 = arith.maxsi %arg1, %arg0 : i32
+ %max2 = arith.maxsi %max1, %arg1 : i32
+ func.return %max2 : i32
+}
+
+// CHECK-LABEL: foldMaxsiMaxsi2
+// CHECK: %[[MAXSI:.*]] = arith.maxsi %arg1, %arg0 : i32
+// CHECK: return %[[MAXSI]] : i32
+func.func public @foldMaxsiMaxsi2(%arg0: i32, %arg1: i32) -> i32 {
+ %max1 = arith.maxsi %arg1, %arg0 : i32
+ %max2 = arith.maxsi %arg1, %max1 : i32
+ func.return %max2 : i32
+}
+
+// CHECK-LABEL: foldMaxsiMinsi1
+// CHECK: return %arg0 : i32
+func.func public @foldMaxsiMinsi1(%arg0: i32, %arg1: i32) -> i32 {
+ %min1 = arith.minsi %arg1, %arg0 : i32
+ %max2 = arith.maxsi %min1, %arg0 : i32
+ func.return %max2 : i32
+}
+
+// CHECK-LABEL: foldMaxsiMinsi2
+// CHECK: return %arg0 : i32
+func.func public @foldMaxsiMinsi2(%arg0: i32, %arg1: i32) -> i32 {
+ %min1 = arith.minsi %arg1, %arg0 : i32
+ %max2 = arith.maxsi %arg0, %min1 : i32
+ func.return %max2 : i32
+}
+
// -----
// CHECK-LABEL: test_maxui
@@ -2018,6 +2052,40 @@ func.func @test_maxui2(%arg0 : i8) -> (i8, i8, i8, i8) {
return %0, %1, %2, %3: i8, i8, i8, i8
}
+// CHECK-LABEL: foldMaxuiMaxui1
+// CHECK: %[[MAXUI:.*]] = arith.maxui %arg1, %arg0 : i32
+// CHECK: return %[[MAXUI]] : i32
+func.func public @foldMaxuiMaxui1(%arg0: i32, %arg1: i32) -> i32 {
+ %max1 = arith.maxui %arg1, %arg0 : i32
+ %max2 = arith.maxui %max1, %arg1 : i32
+ func.return %max2 : i32
+}
+
+// CHECK-LABEL: foldMaxuiMaxui2
+// CHECK: %[[MAXUI:.*]] = arith.maxui %arg1, %arg0 : i32
+// CHECK: return %[[MAXUI]] : i32
+func.func public @foldMaxuiMaxui2(%arg0: i32, %arg1: i32) -> i32 {
+ %max1 = arith.maxui %arg1, %arg0 : i32
+ %max2 = arith.maxui %arg1, %max1 : i32
+ func.return %max2 : i32
+}
+
+// CHECK-LABEL: foldMaxuiMinui1
+// CHECK: return %arg0 : i32
+func.func public @foldMaxuiMinui1(%arg0: i32, %arg1: i32) -> i32 {
+ %min1 = arith.minui %arg1, %arg0 : i32
+ %max2 = arith.maxui %min1, %arg0 : i32
+ func.return %max2 : i32
+}
+
+// CHECK-LABEL: foldMaxuiMinui2
+// CHECK: return %arg0 : i32
+func.func public @foldMaxuiMinui2(%arg0: i32, %arg1: i32) -> i32 {
+ %min1 = arith.minui %arg1, %arg0 : i32
+ %max2 = arith.maxui %arg0, %min1 : i32
+ func.return %max2 : i32
+}
+
// -----
// CHECK-LABEL: test_minsi
@@ -2052,6 +2120,40 @@ func.func @test_minsi2(%arg0 : i8) -> (i8, i8, i8, i8) {
return %0, %1, %2, %3: i8, i8, i8, i8
}
+// CHECK-LABEL: foldMinsiMinsi1
+// CHECK: %[[MINSI:.*]] = arith.minsi %arg1, %arg0 : i32
+// CHECK: return %[[MINSI]] : i32
+func.func public @foldMinsiMinsi1(%arg0: i32, %arg1: i32) -> i32 {
+ %min1 = arith.minsi %arg1, %arg0 : i32
+ %min2 = arith.minsi %min1, %arg1 : i32
+ func.return %min2 : i32
+}
+
+// CHECK-LABEL: foldMinsiMinsi2
+// CHECK: %[[MINSI:.*]] = arith.minsi %arg1, %arg0 : i32
+// CHECK: return %[[MINSI]] : i32
+func.func public @foldMinsiMinsi2(%arg0: i32, %arg1: i32) -> i32 {
+ %min1 = arith.minsi %arg1, %arg0 : i32
+ %min2 = arith.minsi %arg1, %min1 : i32
+ func.return %min2 : i32
+}
+
+// CHECK-LABEL: foldMinsiMaxsi1
+// CHECK: return %arg0 : i32
+func.func public @foldMinsiMaxsi1(%arg0: i32, %arg1: i32) -> i32 {
+ %min1 = arith.maxsi %arg1, %arg0 : i32
+ %min2 = arith.minsi %min1, %arg0 : i32
+ func.return %min2 : i32
+}
+
+// CHECK-LABEL: foldMinsiMaxsi2
+// CHECK: return %arg0 : i32
+func.func public @foldMinsiMaxsi2(%arg0: i32, %arg1: i32) -> i32 {
+ %min1 = arith.maxsi %arg1, %arg0 : i32
+ %min2 = arith.minsi %arg0, %min1 : i32
+ func.return %min2 : i32
+}
+
// -----
// CHECK-LABEL: test_minui
@@ -2086,6 +2188,40 @@ func.func @test_minui2(%arg0 : i8) -> (i8, i8, i8, i8) {
return %0, %1, %2, %3: i8, i8, i8, i8
}
+// CHECK-LABEL: foldMinuiMinui1
+// CHECK: %[[MINUI:.*]] = arith.minui %arg1, %arg0 : i32
+// CHECK: return %[[MINUI]] : i32
+func.func public @foldMinuiMinui1(%arg0: i32, %arg1: i32) -> i32 {
+ %min1 = arith.minui %arg1, %arg0 : i32
+ %min2 = arith.minui %min1, %arg1 : i32
+ func.return %min2 : i32
+}
+
+// CHECK-LABEL: foldMinuiMinui2
+// CHECK: %[[MINUI:.*]] = arith.minui %arg1, %arg0 : i32
+// CHECK: return %[[MINUI]] : i32
+func.func public @foldMinuiMinui2(%arg0: i32, %arg1: i32) -> i32 {
+ %min1 = arith.minui %arg1, %arg0 : i32
+ %min2 = arith.minui %arg1, %min1 : i32
+ func.return %min2 : i32
+}
+
+// CHECK-LABEL: foldMinuiMaxui1
+// CHECK: return %arg0 : i32
+func.func public @foldMinuiMaxui1(%arg0: i32, %arg1: i32) -> i32 {
+ %max1 = arith.maxui %arg1, %arg0 : i32
+ %min2 = arith.minui %max1, %arg0 : i32
+ func.return %min2 : i32
+}
+
+// CHECK-LABEL: foldMinuiMaxui2
+// CHECK: return %arg0 : i32
+func.func public @foldMinuiMaxui2(%arg0: i32, %arg1: i32) -> i32 {
+ %max1 = arith.maxui %arg1, %arg0 : i32
+ %min2 = arith.minui %arg0, %max1 : i32
+ func.return %min2 : i32
+}
+
// -----
// CHECK-LABEL: @test_minimumf(
@@ -3377,4 +3513,3 @@ func.func @unreachable() {
%add = arith.addi %add, %c1_i64 : i64
cf.br ^unreachable
}
-
``````````
</details>
https://github.com/llvm/llvm-project/pull/160224
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