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[MLIR] Zero-extend unsigned and 1-bit values when translating IntegerAttr #169751

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[MLIR] Zero-extend unsigned and 1-bit values when translating IntegerAttr #169751

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[MLIR] Zero-extend unsigned and 1-bit integers when translating to LL…
andykaylor Nov 26, 2025
49c4d1c
Fix global.fir test
andykaylor Dec 1, 2025
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6 changes: 6 additions & 0 deletions clang/test/CIR/CodeGen/globals.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -35,3 +35,9 @@ int *constArrAddr = &arr[2][1];
// LLVM: @constArrAddr = global ptr getelementptr inbounds nuw (i8, ptr @arr, i64 132), align 8

// OGCG: @constArrAddr = global ptr getelementptr (i8, ptr @arr, i64 132), align 8

bool bool_global = true;

// CIR: cir.global external @bool_global = #true {alignment = 1 : i64}
// LLVM: @bool_global = global i8 1, align 1
// OGCG: @bool_global = global i8 1, align 1
2 changes: 1 addition & 1 deletion flang/test/Fir/global.fir
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Expand Up @@ -50,7 +50,7 @@ fir.global internal @_QEmultiarray : !fir.array<32x32xi32> {
fir.has_value %2 : !fir.array<32x32xi32>
}

// CHECK: @_QEmasklogical = internal global [32768 x i32] [i32 -1, i32 -1,
// CHECK: @_QEmasklogical = internal global [32768 x i32] [i32 1, i32 1,
fir.global internal @_QEmasklogical : !fir.array<32768x!fir.logical<4>> {
%true = arith.constant true
%0 = fir.undefined !fir.array<32768x!fir.logical<4>>
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15 changes: 11 additions & 4 deletions mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
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Expand Up @@ -588,10 +588,17 @@ llvm::Constant *mlir::LLVM::detail::getLLVMConstant(
}
// For integer types, we allow a mismatch in sizes as the index type in
// MLIR might have a different size than the index type in the LLVM module.
if (auto intAttr = dyn_cast<IntegerAttr>(attr))
return llvm::ConstantInt::get(
llvmType,
intAttr.getValue().sextOrTrunc(llvmType->getIntegerBitWidth()));
if (auto intAttr = dyn_cast<IntegerAttr>(attr)) {
// If the attribute is an unsigned integer or a 1-bit integer, zero-extend
// the value to the bit width of the LLVM type. Otherwise, sign-extend.
auto intTy = mlir::dyn_cast<IntegerType>(intAttr.getType());
APInt value;
if (intTy && (intTy.isUnsigned() || intTy.getWidth() == 1))
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@andykaylor andykaylor Dec 1, 2025

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I wasn't entirely sure what the condition should be here. Sign-extending a signless value feels a bit arbitrary, but I think that's the behavior that's expected for index types, so I guess it makes sense for signless integers also. My motivation in making this change is that in global initializers true was being translated to i8 -1 whereas in local initializers it was i8 1.

value = intAttr.getValue().zextOrTrunc(llvmType->getIntegerBitWidth());
else
value = intAttr.getValue().sextOrTrunc(llvmType->getIntegerBitWidth());
return llvm::ConstantInt::get(llvmType, value);
}
if (auto floatAttr = dyn_cast<FloatAttr>(attr)) {
const llvm::fltSemantics &sem = floatAttr.getValue().getSemantics();
// Special case for 8-bit floats, which are represented by integers due to
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3 changes: 3 additions & 0 deletions mlir/test/Target/LLVMIR/llvmir.mlir
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Expand Up @@ -78,6 +78,9 @@ llvm.mlir.global internal @f8E8M0FNU_global_as_i8(1.0 : f8E8M0FNU) : i8
// CHECK: @bf16_global_as_i16 = internal global i16 16320
llvm.mlir.global internal @bf16_global_as_i16(1.5 : bf16) : i16

// CHECK: @bool_global_as_i8 = internal global i8 1
llvm.mlir.global internal @bool_global_as_i8(true) : i8

// CHECK: @explicit_undef = global i32 undef
llvm.mlir.global external @explicit_undef() : i32 {
%0 = llvm.mlir.undef : i32
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