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[CIR][CIRGen][Builtin][X86] Lower lzcnt_u16, lzcnt_u32, lzcnt_u64 #1683

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Merged
merged 1 commit into from
Jun 18, 2025
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[CIR][CIRGen][Builtin][X86] Lower lzcnt_u16, lzcnt_u32, lzcnt_u64 #1683

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15 changes: 15 additions & 0 deletions clang/lib/CIR/CodeGen/CIRGenBuiltinX86.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -144,5 +144,20 @@ mlir::Value CIRGenFunction::emitX86BuiltinExpr(unsigned BuiltinID,
getLoc(E->getExprLoc()), builder.getStringAttr("x86.rdtsc"), intTy)
.getResult();
}
case X86::BI__builtin_ia32_rdtscp: {
llvm_unreachable("__rdtscp NYI");
}
case X86::BI__builtin_ia32_lzcnt_u16:
case X86::BI__builtin_ia32_lzcnt_u32:
case X86::BI__builtin_ia32_lzcnt_u64: {
mlir::Value V = builder.create<cir::ConstantOp>(
getLoc(E->getExprLoc()), cir::BoolAttr::get(&getMLIRContext(), false));

return builder
.create<cir::LLVMIntrinsicCallOp>(
getLoc(E->getExprLoc()), builder.getStringAttr("ctlz"),
Ops[0].getType(), mlir::ValueRange{Ops[0], V})
.getResult();
}
}
}
24 changes: 24 additions & 0 deletions clang/test/CIR/CodeGen/X86/lzcnt-builtins.c
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Original file line number Diff line number Diff line change
@@ -0,0 +1,24 @@
// RUN: %clang_cc1 -ffreestanding -triple x86_64-unknown-linux -Wno-implicit-function-declaration -fclangir -emit-cir -o %t.cir %s
// RUN: FileCheck --check-prefix=CIR --input-file=%t.cir %s
// RUN: %clang_cc1 -ffreestanding -triple x86_64-unknown-linux -Wno-implicit-function-declaration -fclangir -emit-llvm -o %t.ll %s
// RUN: FileCheck --check-prefix=LLVM --input-file=%t.ll %s

#include <immintrin.h>

unsigned int test_lzcnt_u32(unsigned int __X)
{
// CIR-LABEL: _lzcnt_u32
// LLVM-LABEL: _lzcnt_u32
return _lzcnt_u32(__X);
// CIR: {{%.*}} = cir.llvm.intrinsic "ctlz" {{%.*}} : (!u32i, !cir.bool) -> !u32i
// LLVM: @llvm.ctlz.i32(i32 %{{.*}}, i1 false)
}

unsigned long long test__lzcnt_u64(unsigned long long __X)
{
// CIR-LABEL: _lzcnt_u64
// LLVM-LABEL: _lzcnt_u64
return _lzcnt_u64(__X);
// CIR: {{%.*}} = cir.llvm.intrinsic "ctlz" {{%.*}} : (!u64i, !cir.bool) -> !u64i
// LLVM: @llvm.ctlz.i64(i64 %{{.*}}, i1 false)
}
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