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[mlir][arith][transforms] Fix f4E2M1FN to f32 cast #160121

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Merged
merged 1 commit into from
Sep 22, 2025
Merged

[mlir][arith][transforms] Fix f4E2M1FN to f32 cast #160121

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11 changes: 7 additions & 4 deletions mlir/lib/Dialect/Arith/Transforms/ExpandOps.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -387,12 +387,15 @@ struct F4E2M1ExtFOpConverter : public OpRewritePattern<arith::ExtFOp> {
Value c0x1 = createConst(loc, i4Ty, 0x1, rewriter);
Value c0x2 = createConst(loc, i4Ty, 0x2, rewriter);
Value c0x4 = createConst(loc, i4Ty, 0x4, rewriter);
Value c0x7 = createConst(loc, i4Ty, 0x7, rewriter);

Value i4BitsNoSign = arith::AndIOp::create(b, i4Bits, c0x7);

// Set last Exponent bit and Mantissa.
Value c0x00000014 = createConst(loc, i32Ty, 0x14, rewriter);
Value bits1To24 = arith::ShLIOp::create(b, i4Bits, c0x2);
Value bits1To24 = arith::ShLIOp::create(b, i4BitsNoSign, c0x2);
Value isHalf =
arith::CmpIOp::create(b, arith::CmpIPredicate::eq, i4Bits, c0x1);
arith::CmpIOp::create(b, arith::CmpIPredicate::eq, i4BitsNoSign, c0x1);
bits1To24 = arith::SelectOp::create(b, isHalf, c0x0, bits1To24);
bits1To24 = arith::ExtUIOp::create(b, i32Ty, bits1To24);
bits1To24 = arith::ShLIOp::create(b, bits1To24, c0x00000014);
Expand All @@ -402,11 +405,11 @@ struct F4E2M1ExtFOpConverter : public OpRewritePattern<arith::ExtFOp> {
Value highExpBits = createConst(loc, i32Ty, 0x40000000, rewriter);
Value lowExpBits = createConst(loc, i32Ty, 0x3f000000, rewriter);
Value useLargerExp =
arith::CmpIOp::create(b, arith::CmpIPredicate::uge, i4Bits, c0x4);
arith::CmpIOp::create(b, arith::CmpIPredicate::uge, i4BitsNoSign, c0x4);
Value bits25To31 =
arith::SelectOp::create(b, useLargerExp, highExpBits, lowExpBits);
Value zeroExp =
arith::CmpIOp::create(b, arith::CmpIPredicate::eq, i4Bits, c0x0);
arith::CmpIOp::create(b, arith::CmpIPredicate::eq, i4BitsNoSign, c0x0);
bits25To31 = arith::SelectOp::create(b, zeroExp, zeroExpBits, bits25To31);

// Set sign.
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67 changes: 67 additions & 0 deletions mlir/test/Integration/Dialect/Arith/CPU/test-arith-expand-truncf-extf.mlir
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Expand Up @@ -28,7 +28,18 @@ func.func @entry() {
%zero = arith.constant 0.0 : f32
%half = arith.constant 0.5 : f32
%one = arith.constant 1.0 : f32
%oneAndAHalf = arith.constant 1.5 : f32
%two = arith.constant 2.0 : f32
%three = arith.constant 3.0 : f32
%four = arith.constant 4.0 : f32
%max = arith.constant 6.0 : f32
%minZero = arith.constant -0.0 : f32
%minHalf = arith.constant -0.5 : f32
%minOne = arith.constant -1.0 : f32
%minOneAndAHalf = arith.constant -1.5 : f32
%minTwo = arith.constant -2.0 : f32
%minThree = arith.constant -3.0 : f32
%minFour = arith.constant -4.0 : f32
%min = arith.constant -6.0 : f32
%lowerThanMin = arith.constant -1000000.0 : f32
%higherThanMax = arith.constant 1000000.0 : f32
Expand All @@ -41,8 +52,28 @@ func.func @entry() {
func.call @check_truncf(%half) : (f32) -> ()
// CHECK: 2
func.call @check_truncf(%one) : (f32) -> ()
// CHECK: 3
func.call @check_truncf(%oneAndAHalf) : (f32) -> ()
// CHECK: 4
func.call @check_truncf(%two) : (f32) -> ()
// CHECK: 5
func.call @check_truncf(%three) : (f32) -> ()
// CHECK: 6
func.call @check_truncf(%four) : (f32) -> ()
// CHECK: 7
func.call @check_truncf(%max) : (f32) -> ()
// CHECK: 9
func.call @check_truncf(%minHalf) : (f32) -> ()
// CHECK: 10
func.call @check_truncf(%minOne) : (f32) -> ()
// CHECK: 11
func.call @check_truncf(%minOneAndAHalf) : (f32) -> ()
// CHECK: 12
func.call @check_truncf(%minTwo) : (f32) -> ()
// CHECK: 13
func.call @check_truncf(%minThree) : (f32) -> ()
// CHECK: 14
func.call @check_truncf(%minFour) : (f32) -> ()
// CHECK: 15
func.call @check_truncf(%min) : (f32) -> ()
// CHECK: 7
Expand All @@ -60,9 +91,45 @@ func.func @entry() {
// CHECK: 0.5
%halfF4 = arith.truncf %half : f32 to f4E2M1FN
func.call @check_extf(%halfF4) : (f4E2M1FN) -> ()
// CHECK: 1
%oneF4 = arith.truncf %one : f32 to f4E2M1FN
func.call @check_extf(%oneF4) : (f4E2M1FN) -> ()
// CHECK: 1.5
%oneAndAHalfF4 = arith.truncf %oneAndAHalf : f32 to f4E2M1FN
func.call @check_extf(%oneAndAHalfF4) : (f4E2M1FN) -> ()
// CHECK: 2
%twoF4 = arith.truncf %two : f32 to f4E2M1FN
func.call @check_extf(%twoF4) : (f4E2M1FN) -> ()
// CHECK: 3
%threeF4 = arith.truncf %three : f32 to f4E2M1FN
func.call @check_extf(%threeF4) : (f4E2M1FN) -> ()
// CHECK: 4
%fourF4 = arith.truncf %four : f32 to f4E2M1FN
func.call @check_extf(%fourF4) : (f4E2M1FN) -> ()
// CHECK: 6
%higherThanMaxF4 = arith.truncf %higherThanMax : f32 to f4E2M1FN
func.call @check_extf(%higherThanMaxF4) : (f4E2M1FN) -> ()
// CHECK: -0
%minZeroF4 = arith.truncf %minZero : f32 to f4E2M1FN
func.call @check_extf(%minZeroF4) : (f4E2M1FN) -> ()
// CHECK: -0.5
%minHalfF4 = arith.truncf %minHalf : f32 to f4E2M1FN
func.call @check_extf(%minHalfF4) : (f4E2M1FN) -> ()
// CHECK: -1
%minOneF4 = arith.truncf %minOne : f32 to f4E2M1FN
func.call @check_extf(%minOneF4) : (f4E2M1FN) -> ()
// CHECK: -1.5
%minOneAndAHalfF4 = arith.truncf %minOneAndAHalf : f32 to f4E2M1FN
func.call @check_extf(%minOneAndAHalfF4) : (f4E2M1FN) -> ()
// CHECK: -2
%minTwoF4 = arith.truncf %minTwo : f32 to f4E2M1FN
func.call @check_extf(%minTwoF4) : (f4E2M1FN) -> ()
// CHECK: -3
%minThreeF4 = arith.truncf %minThree : f32 to f4E2M1FN
func.call @check_extf(%minThreeF4) : (f4E2M1FN) -> ()
// CHECK: -4
%minFourF4 = arith.truncf %minFour : f32 to f4E2M1FN
func.call @check_extf(%minFourF4) : (f4E2M1FN) -> ()
// CHECK: -6
%lowerThanMinF4 = arith.truncf %lowerThanMin : f32 to f4E2M1FN
func.call @check_extf(%lowerThanMinF4) : (f4E2M1FN) -> ()
Expand Down