[mlir][arith] Fix arith.select canonicalization patterns
#84685
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Because `arith.select` does not propagate poison of the second or third operand depending on the condition, some canonicalization patterns were incorrect. This patch removes these incorrect patterns, and adds a new pattern to fix the case of `i1` select with constants. Patterns that are removed: * select(predA, select(predB, x, y), y) => select(and(predA, predB), x, y) * select(predA, select(predB, y, x), y) => select(and(predA, not(predB)), x, y) * select(predA, x, select(predB, x, y)) => select(or(predA, predB), x, y) * select(predA, x, select(predB, y, x)) => select(or(predA, not(predB)), x, y) * arith.select %arg, %x, %y : i1 => and(%arg, %x) or and(!%arg, %y) The first two patterns are incorrect when `predB` is poison and `predA` is false, as a non-poison `y` gets compiled to `poison`. The next two patterns are incorrect when `predB` is poison and `predA` is true, as a non-poison `x` gets compiled to `poison`. The last pattern is incorrect as it propagates poison from all operands afer compilation.
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@llvm/pr-subscribers-mlir @llvm/pr-subscribers-mlir-arith Author: Fehr Mathieu (math-fehr) ChangesBecause Patterns that are removed:
Pattern that is added:
The first two patterns are incorrect when Full diff: https://github.com/llvm/llvm-project/pull/84685.diff 3 Files Affected:
diff --git a/mlir/lib/Dialect/Arith/IR/ArithCanonicalization.td b/mlir/lib/Dialect/Arith/IR/ArithCanonicalization.td
index 11c4a29718e1d9..caca2ff81964f7 100644
--- a/mlir/lib/Dialect/Arith/IR/ArithCanonicalization.td
+++ b/mlir/lib/Dialect/Arith/IR/ArithCanonicalization.td
@@ -253,9 +253,6 @@ def CmpIExtUI :
// SelectOp
//===----------------------------------------------------------------------===//
-def GetScalarOrVectorTrueAttribute :
- NativeCodeCall<"cast<TypedAttr>(getBoolAttribute($0.getType(), true))">;
-
// select(not(pred), a, b) => select(pred, b, a)
def SelectNotCond :
Pat<(SelectOp (Arith_XOrIOp $pred, (ConstantLikeMatcher APIntAttr:$ones)), $a, $b),
@@ -272,31 +269,12 @@ def RedundantSelectFalse :
Pat<(SelectOp $pred, $a, (SelectOp $pred, $b, $c)),
(SelectOp $pred, $a, $c)>;
-// select(predA, select(predB, x, y), y) => select(and(predA, predB), x, y)
-def SelectAndCond :
- Pat<(SelectOp $predA, (SelectOp $predB, $x, $y), $y),
- (SelectOp (Arith_AndIOp $predA, $predB), $x, $y)>;
-
-// select(predA, select(predB, y, x), y) => select(and(predA, not(predB)), x, y)
-def SelectAndNotCond :
- Pat<(SelectOp $predA, (SelectOp $predB, $y, $x), $y),
- (SelectOp (Arith_AndIOp $predA,
- (Arith_XOrIOp $predB,
- (Arith_ConstantOp (GetScalarOrVectorTrueAttribute $predB)))),
- $x, $y)>;
-
-// select(predA, x, select(predB, x, y)) => select(or(predA, predB), x, y)
-def SelectOrCond :
- Pat<(SelectOp $predA, $x, (SelectOp $predB, $x, $y)),
- (SelectOp (Arith_OrIOp $predA, $predB), $x, $y)>;
-
-// select(predA, x, select(predB, y, x)) => select(or(predA, not(predB)), x, y)
-def SelectOrNotCond :
- Pat<(SelectOp $predA, $x, (SelectOp $predB, $y, $x)),
- (SelectOp (Arith_OrIOp $predA,
- (Arith_XOrIOp $predB,
- (Arith_ConstantOp (GetScalarOrVectorTrueAttribute $predB)))),
- $x, $y)>;
+// select(pred, false, true) => not(pred)
+def SelectI1ToNot :
+ Pat<(SelectOp $pred,
+ (ConstantLikeMatcher ConstantAttr<I1Attr, "0">),
+ (ConstantLikeMatcher ConstantAttr<I1Attr, "1">)),
+ (Arith_XOrIOp $pred, (Arith_ConstantOp ConstantAttr<I1Attr, "1">))>;
//===----------------------------------------------------------------------===//
// IndexCastOp
diff --git a/mlir/lib/Dialect/Arith/IR/ArithOps.cpp b/mlir/lib/Dialect/Arith/IR/ArithOps.cpp
index 0f71c19c23b654..9f64a07f31e3af 100644
--- a/mlir/lib/Dialect/Arith/IR/ArithOps.cpp
+++ b/mlir/lib/Dialect/Arith/IR/ArithOps.cpp
@@ -969,7 +969,6 @@ OpFoldResult arith::MaxNumFOp::fold(FoldAdaptor adaptor) {
[](const APFloat &a, const APFloat &b) { return llvm::maximum(a, b); });
}
-
//===----------------------------------------------------------------------===//
// MaxSIOp
//===----------------------------------------------------------------------===//
@@ -2173,35 +2172,6 @@ void arith::CmpFOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
// SelectOp
//===----------------------------------------------------------------------===//
-// Transforms a select of a boolean to arithmetic operations
-//
-// arith.select %arg, %x, %y : i1
-//
-// becomes
-//
-// and(%arg, %x) or and(!%arg, %y)
-struct SelectI1Simplify : public OpRewritePattern<arith::SelectOp> {
- using OpRewritePattern<arith::SelectOp>::OpRewritePattern;
-
- LogicalResult matchAndRewrite(arith::SelectOp op,
- PatternRewriter &rewriter) const override {
- if (!op.getType().isInteger(1))
- return failure();
-
- Value falseConstant =
- rewriter.create<arith::ConstantIntOp>(op.getLoc(), true, 1);
- Value notCondition = rewriter.create<arith::XOrIOp>(
- op.getLoc(), op.getCondition(), falseConstant);
-
- Value trueVal = rewriter.create<arith::AndIOp>(
- op.getLoc(), op.getCondition(), op.getTrueValue());
- Value falseVal = rewriter.create<arith::AndIOp>(op.getLoc(), notCondition,
- op.getFalseValue());
- rewriter.replaceOpWithNewOp<arith::OrIOp>(op, trueVal, falseVal);
- return success();
- }
-};
-
// select %arg, %c1, %c0 => extui %arg
struct SelectToExtUI : public OpRewritePattern<arith::SelectOp> {
using OpRewritePattern<arith::SelectOp>::OpRewritePattern;
@@ -2238,9 +2208,8 @@ struct SelectToExtUI : public OpRewritePattern<arith::SelectOp> {
void arith::SelectOp::getCanonicalizationPatterns(RewritePatternSet &results,
MLIRContext *context) {
- results.add<RedundantSelectFalse, RedundantSelectTrue, SelectI1Simplify,
- SelectAndCond, SelectAndNotCond, SelectOrCond, SelectOrNotCond,
- SelectNotCond, SelectToExtUI>(context);
+ results.add<RedundantSelectFalse, RedundantSelectTrue, SelectNotCond,
+ SelectI1ToNot, SelectToExtUI>(context);
}
OpFoldResult arith::SelectOp::fold(FoldAdaptor adaptor) {
diff --git a/mlir/test/Dialect/Arith/canonicalize.mlir b/mlir/test/Dialect/Arith/canonicalize.mlir
index cb98a10048a309..bdc6c91d926775 100644
--- a/mlir/test/Dialect/Arith/canonicalize.mlir
+++ b/mlir/test/Dialect/Arith/canonicalize.mlir
@@ -116,18 +116,6 @@ func.func @selToNot(%arg0: i1) -> i1 {
return %res : i1
}
-// CHECK-LABEL: @selToArith
-// CHECK-NEXT: %[[trueval:.+]] = arith.constant true
-// CHECK-NEXT: %[[notcmp:.+]] = arith.xori %arg0, %[[trueval]] : i1
-// CHECK-NEXT: %[[condtrue:.+]] = arith.andi %arg0, %arg1 : i1
-// CHECK-NEXT: %[[condfalse:.+]] = arith.andi %[[notcmp]], %arg2 : i1
-// CHECK-NEXT: %[[res:.+]] = arith.ori %[[condtrue]], %[[condfalse]] : i1
-// CHECK: return %[[res]]
-func.func @selToArith(%arg0: i1, %arg1 : i1, %arg2 : i1) -> i1 {
- %res = arith.select %arg0, %arg1, %arg2 : i1
- return %res : i1
-}
-
// CHECK-LABEL: @redundantSelectTrue
// CHECK-NEXT: %[[res:.+]] = arith.select %arg0, %arg1, %arg3
// CHECK-NEXT: return %[[res]]
@@ -160,74 +148,6 @@ func.func @selNotCond(%arg0: i1, %arg1 : i32, %arg2 : i32, %arg3 : i32, %arg4 :
return %res1, %res2 : i32, i32
}
-// CHECK-LABEL: @selAndCond
-// CHECK-NEXT: %[[and:.+]] = arith.andi %arg1, %arg0
-// CHECK-NEXT: %[[res:.+]] = arith.select %[[and]], %arg2, %arg3
-// CHECK-NEXT: return %[[res]]
-func.func @selAndCond(%arg0: i1, %arg1: i1, %arg2 : i32, %arg3 : i32) -> i32 {
- %sel = arith.select %arg0, %arg2, %arg3 : i32
- %res = arith.select %arg1, %sel, %arg3 : i32
- return %res : i32
-}
-
-// CHECK-LABEL: @selAndNotCond
-// CHECK-NEXT: %[[one:.+]] = arith.constant true
-// CHECK-NEXT: %[[not:.+]] = arith.xori %arg0, %[[one]]
-// CHECK-NEXT: %[[and:.+]] = arith.andi %arg1, %[[not]]
-// CHECK-NEXT: %[[res:.+]] = arith.select %[[and]], %arg3, %arg2
-// CHECK-NEXT: return %[[res]]
-func.func @selAndNotCond(%arg0: i1, %arg1: i1, %arg2 : i32, %arg3 : i32) -> i32 {
- %sel = arith.select %arg0, %arg2, %arg3 : i32
- %res = arith.select %arg1, %sel, %arg2 : i32
- return %res : i32
-}
-
-// CHECK-LABEL: @selAndNotCondVec
-// CHECK-NEXT: %[[one:.+]] = arith.constant dense<true> : vector<4xi1>
-// CHECK-NEXT: %[[not:.+]] = arith.xori %arg0, %[[one]]
-// CHECK-NEXT: %[[and:.+]] = arith.andi %arg1, %[[not]]
-// CHECK-NEXT: %[[res:.+]] = arith.select %[[and]], %arg3, %arg2
-// CHECK-NEXT: return %[[res]]
-func.func @selAndNotCondVec(%arg0: vector<4xi1>, %arg1: vector<4xi1>, %arg2 : vector<4xi32>, %arg3 : vector<4xi32>) -> vector<4xi32> {
- %sel = arith.select %arg0, %arg2, %arg3 : vector<4xi1>, vector<4xi32>
- %res = arith.select %arg1, %sel, %arg2 : vector<4xi1>, vector<4xi32>
- return %res : vector<4xi32>
-}
-
-// CHECK-LABEL: @selOrCond
-// CHECK-NEXT: %[[or:.+]] = arith.ori %arg1, %arg0
-// CHECK-NEXT: %[[res:.+]] = arith.select %[[or]], %arg2, %arg3
-// CHECK-NEXT: return %[[res]]
-func.func @selOrCond(%arg0: i1, %arg1: i1, %arg2 : i32, %arg3 : i32) -> i32 {
- %sel = arith.select %arg0, %arg2, %arg3 : i32
- %res = arith.select %arg1, %arg2, %sel : i32
- return %res : i32
-}
-
-// CHECK-LABEL: @selOrNotCond
-// CHECK-NEXT: %[[one:.+]] = arith.constant true
-// CHECK-NEXT: %[[not:.+]] = arith.xori %arg0, %[[one]]
-// CHECK-NEXT: %[[or:.+]] = arith.ori %arg1, %[[not]]
-// CHECK-NEXT: %[[res:.+]] = arith.select %[[or]], %arg3, %arg2
-// CHECK-NEXT: return %[[res]]
-func.func @selOrNotCond(%arg0: i1, %arg1: i1, %arg2 : i32, %arg3 : i32) -> i32 {
- %sel = arith.select %arg0, %arg2, %arg3 : i32
- %res = arith.select %arg1, %arg3, %sel : i32
- return %res : i32
-}
-
-// CHECK-LABEL: @selOrNotCondVec
-// CHECK-NEXT: %[[one:.+]] = arith.constant dense<true> : vector<4xi1>
-// CHECK-NEXT: %[[not:.+]] = arith.xori %arg0, %[[one]]
-// CHECK-NEXT: %[[or:.+]] = arith.ori %arg1, %[[not]]
-// CHECK-NEXT: %[[res:.+]] = arith.select %[[or]], %arg3, %arg2
-// CHECK-NEXT: return %[[res]]
-func.func @selOrNotCondVec(%arg0: vector<4xi1>, %arg1: vector<4xi1>, %arg2 : vector<4xi32>, %arg3 : vector<4xi32>) -> vector<4xi32> {
- %sel = arith.select %arg0, %arg2, %arg3 : vector<4xi1>, vector<4xi32>
- %res = arith.select %arg1, %arg3, %sel : vector<4xi1>, vector<4xi32>
- return %res : vector<4xi32>
-}
-
// Test case: Folding of comparisons with equal operands.
// CHECK-LABEL: @cmpi_equal_operands
// CHECK-DAG: %[[T:.*]] = arith.constant true
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kuhar
approved these changes
Mar 10, 2024
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Because
arith.selectdoes not propagate poison of the second or third operand depending on the condition, some canonicalization patterns are currently incorrect. This patch removes these incorrect patterns, and adds a new pattern to fix the case ofi1select with constants.Patterns that are removed:
Pattern that is added:
The first two patterns are incorrect when
predBis poison andpredAis false, as a non-poisonygets compiled topoison. The next two patterns are incorrect whenpredBis poison andpredAis true, as a non-poisonxgets compiled topoison. The last pattern is incorrect as it propagates poison from all operands afer compilation.