https://github.com/xakep8 created https://github.com/llvm/llvm-project/pull/214931
Added CIRGen support for __builtin_stdc_trailing_zeros by lowering it to cir.ctz with zero behaviour defined, matching with the C23 stdbit semantics. Added CodeGen test for the same. FIxes #214443 >From 72297a6b7a99238527e926e29392fda314201c4f Mon Sep 17 00:00:00 2001 From: Kunal Dubey <[email protected]> Date: Sat, 8 Aug 2026 10:19:23 +0530 Subject: [PATCH] [CIR] Lowering __builtin_stdc_trailing_zeros Added CIRGen support for __builtin_stdc_trailing_zeros by lowering it to cir.ctz with zero behaviour defined, matching with the C23 stdbit semantics. Added CodeGen test for the same. --- clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp | 7 +++++++ clang/test/CIR/CodeGenBuiltins/builtin-stdc-bit.c | 10 ++++++++++ 2 files changed, 17 insertions(+) create mode 100644 clang/test/CIR/CodeGenBuiltins/builtin-stdc-bit.c diff --git a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp index 1efe2b81d5cae..2eb9d6c3bb661 100644 --- a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp +++ b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp @@ -1247,6 +1247,13 @@ RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl &gd, unsigned builtinID, getTarget().isCLZForZeroUndef()); case Builtin::BI__builtin_ctzg: return emitBuiltinBitOpWithFallback<cir::BitCtzOp>(*this, e); + case Builtin::BIstdc_trailing_zeros_uc: + case Builtin::BIstdc_trailing_zeros_us: + case Builtin::BIstdc_trailiing_zeros_ui: + case Builtin::BIstdc_trailing_zeros_ul: + case Builtin::BIstdc_trailing_zeros_ull: + case Builtin::BI__builtin_stdc_trailing_zeros: + return emitBuiltinBitOp<cir::BitCtzOp>(*this, e, /*poisonZero=*/false); case Builtin::BI__builtin_clzs: case Builtin::BI__builtin_clz: diff --git a/clang/test/CIR/CodeGenBuiltins/builtin-stdc-bit.c b/clang/test/CIR/CodeGenBuiltins/builtin-stdc-bit.c new file mode 100644 index 0000000000000..6d285c259a96f --- /dev/null +++ b/clang/test/CIR/CodeGenBuiltins/builtin-stdc-bit.c @@ -0,0 +1,10 @@ +// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o - | FileCheck %s + +void test_stdc_trailing_zeros(unsigned long long x) { + int cnt = __builtin_stdc_trailing_zeros(x); + (void)cnt; +} + +// CHECK-LABEL: test_stdc_trailing_zeros +// CHECK: cir.ctz +// CHECK-NOT: poison_zero _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
