[mlir][tosa] Fix integer-to-boolean cast folder #150370
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According to the TOSA spec, casting to boolean should produce true if the input is non-zero, and false otherwise — i.e., `out = (in != 0) ? true : false`. Previous behavior incorrectly relied on truncation, which could yield incorrect results for non-zero values whose least significant bit is zero.
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@llvm/pr-subscribers-mlir Author: Longsheng Mou (CoTinker) ChangesAccording to the TOSA spec, casting to boolean should produce true if the input is non-zero, and false otherwise — i.e., Full diff: https://github.com/llvm/llvm-project/pull/150370.diff 2 Files Affected:
diff --git a/mlir/lib/Dialect/Tosa/IR/TosaCanonicalizations.cpp b/mlir/lib/Dialect/Tosa/IR/TosaCanonicalizations.cpp
index 606626dfe4d2c..080955bf94761 100644
--- a/mlir/lib/Dialect/Tosa/IR/TosaCanonicalizations.cpp
+++ b/mlir/lib/Dialect/Tosa/IR/TosaCanonicalizations.cpp
@@ -1302,9 +1302,13 @@ OpFoldResult CastOp::fold(FoldAdaptor adaptor) {
auto intVal = operand.getSplatValue<APInt>();
auto bitwidth = outETy.getIntOrFloatBitWidth();
+ // i1 types are boolean in TOSA
if (trunc) {
- intVal = intVal.trunc(bitwidth);
- // i1 types are boolean in TOSA
+ if (outETy.isInteger(1)) {
+ intVal = intVal.isZero() ? APInt(bitwidth, 0) : APInt(bitwidth, 1);
+ } else {
+ intVal = intVal.trunc(bitwidth);
+ }
} else if (unsignIn || inIntType.isInteger(1)) {
intVal = intVal.zext(bitwidth);
} else {
diff --git a/mlir/test/Dialect/Tosa/canonicalize.mlir b/mlir/test/Dialect/Tosa/canonicalize.mlir
index 11c8d54fda055..6b55442a82a0a 100644
--- a/mlir/test/Dialect/Tosa/canonicalize.mlir
+++ b/mlir/test/Dialect/Tosa/canonicalize.mlir
@@ -1349,3 +1349,14 @@ func.func @test_fold_i1_to_i32_cast() -> tensor<i32> {
%1 = "tosa.cast"(%0) : (tensor<i1>) -> tensor<i32>
return %1 : tensor<i32>
}
+
+// -----
+
+// CHECK-LABEL: @test_fold_i32_to_i1_cast
+// CHECK: %[[OUT:.*]] = "tosa.const"() <{values = dense<true> : tensor<i1>}> : () -> tensor<i1>
+// CHECK: return %[[OUT]] : tensor<i1>
+func.func @test_fold_i32_to_i1_cast() -> tensor<i1> {
+ %0 = "tosa.const"() <{values = dense<10> : tensor<i32>}> : () -> tensor<i32>
+ %1 = "tosa.cast"(%0) : (tensor<i32>) -> tensor<i1>
+ return %1 : tensor<i1>
+}
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Member
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@llvm/pr-subscribers-mlir-tosa Author: Longsheng Mou (CoTinker) ChangesAccording to the TOSA spec, casting to boolean should produce true if the input is non-zero, and false otherwise — i.e., Full diff: https://github.com/llvm/llvm-project/pull/150370.diff 2 Files Affected:
diff --git a/mlir/lib/Dialect/Tosa/IR/TosaCanonicalizations.cpp b/mlir/lib/Dialect/Tosa/IR/TosaCanonicalizations.cpp
index 606626dfe4d2c..080955bf94761 100644
--- a/mlir/lib/Dialect/Tosa/IR/TosaCanonicalizations.cpp
+++ b/mlir/lib/Dialect/Tosa/IR/TosaCanonicalizations.cpp
@@ -1302,9 +1302,13 @@ OpFoldResult CastOp::fold(FoldAdaptor adaptor) {
auto intVal = operand.getSplatValue<APInt>();
auto bitwidth = outETy.getIntOrFloatBitWidth();
+ // i1 types are boolean in TOSA
if (trunc) {
- intVal = intVal.trunc(bitwidth);
- // i1 types are boolean in TOSA
+ if (outETy.isInteger(1)) {
+ intVal = intVal.isZero() ? APInt(bitwidth, 0) : APInt(bitwidth, 1);
+ } else {
+ intVal = intVal.trunc(bitwidth);
+ }
} else if (unsignIn || inIntType.isInteger(1)) {
intVal = intVal.zext(bitwidth);
} else {
diff --git a/mlir/test/Dialect/Tosa/canonicalize.mlir b/mlir/test/Dialect/Tosa/canonicalize.mlir
index 11c8d54fda055..6b55442a82a0a 100644
--- a/mlir/test/Dialect/Tosa/canonicalize.mlir
+++ b/mlir/test/Dialect/Tosa/canonicalize.mlir
@@ -1349,3 +1349,14 @@ func.func @test_fold_i1_to_i32_cast() -> tensor<i32> {
%1 = "tosa.cast"(%0) : (tensor<i1>) -> tensor<i32>
return %1 : tensor<i32>
}
+
+// -----
+
+// CHECK-LABEL: @test_fold_i32_to_i1_cast
+// CHECK: %[[OUT:.*]] = "tosa.const"() <{values = dense<true> : tensor<i1>}> : () -> tensor<i1>
+// CHECK: return %[[OUT]] : tensor<i1>
+func.func @test_fold_i32_to_i1_cast() -> tensor<i1> {
+ %0 = "tosa.const"() <{values = dense<10> : tensor<i32>}> : () -> tensor<i32>
+ %1 = "tosa.cast"(%0) : (tensor<i32>) -> tensor<i1>
+ return %1 : tensor<i1>
+}
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lhutton1
approved these changes
Jul 24, 2025
mahesh-attarde
pushed a commit
to mahesh-attarde/llvm-project
that referenced
this pull request
Jul 28, 2025
According to the TOSA spec, casting to boolean should produce true if the input is non-zero, and false otherwise — i.e., `out = (in != 0) ? true : false`. Previous behavior incorrectly relied on truncation, which could yield incorrect results for non-zero values whose least significant bit is zero. Fixes llvm#150302.
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According to the TOSA spec, casting to boolean should produce true if the input is non-zero, and false otherwise — i.e.,
out = (in != 0) ? true : false. Previous behavior incorrectly relied on truncation, which could yield incorrect results for non-zero values whose least significant bit is zero. Fixes #150302.