https://github.com/c8ef created https://github.com/llvm/llvm-project/pull/112459
The current built-in abs function cannot be used in a constexpr environment. This patch fixes the issue. See also: https://godbolt.org/z/s8x3Yd8ne. >From dfa1585af3f080987cbd15830c45c34bfecc1fca Mon Sep 17 00:00:00 2001 From: c8ef <c...@outlook.com> Date: Wed, 16 Oct 2024 01:18:13 +0000 Subject: [PATCH] implement constexpr builtin {l}abs --- clang/include/clang/Basic/Builtins.td | 1 + clang/lib/AST/ExprConstant.cpp | 11 +++++++++++ clang/test/AST/ByteCode/builtin-functions.cpp | 9 +++++++++ 3 files changed, 21 insertions(+) diff --git a/clang/include/clang/Basic/Builtins.td b/clang/include/clang/Basic/Builtins.td index bda8a48be92bda..e1b4d5b1fdc0a5 100644 --- a/clang/include/clang/Basic/Builtins.td +++ b/clang/include/clang/Basic/Builtins.td @@ -2714,6 +2714,7 @@ def Abs : IntMathTemplate, LibBuiltin<"stdlib.h"> { let Attributes = [NoThrow, Const]; let Prototype = "T(T)"; let AddBuiltinPrefixedAlias = 1; + let OnlyBuiltinPrefixedAliasIsConstexpr = 1; } def Calloc : LibBuiltin<"stdlib.h"> { diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index 52a7f5778ce6d2..69539a7f03feba 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -13055,6 +13055,17 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E, return Success(Val.popcount() % 2, E); } + case Builtin::BI__builtin_abs: + case Builtin::BI__builtin_labs: + case Builtin::BI__builtin_llabs: { + APSInt Val; + if (!EvaluateInteger(E->getArg(0), Val, Info)) + return false; + if (Val.isNegative()) + Val.negate(); + return Success(Val, E); + } + case Builtin::BI__builtin_popcount: case Builtin::BI__builtin_popcountl: case Builtin::BI__builtin_popcountll: diff --git a/clang/test/AST/ByteCode/builtin-functions.cpp b/clang/test/AST/ByteCode/builtin-functions.cpp index 450ff5671314db..46e5b0579bd575 100644 --- a/clang/test/AST/ByteCode/builtin-functions.cpp +++ b/clang/test/AST/ByteCode/builtin-functions.cpp @@ -265,6 +265,15 @@ namespace fpclassify { char classify_subnorm [__builtin_fpclassify(-1, -1, -1, +1, -1, 1.0e-38f)]; } +namespace abs { +static_assert(__builtin_abs(14) == 14, ""); +static_assert(__builtin_labs(14L) == 14L, ""); +static_assert(__builtin_llabs(14LL) == 14LL, ""); +static_assert(__builtin_abs(-14) == 14, ""); +static_assert(__builtin_labs(-14L) == 14L, ""); +static_assert(__builtin_llabs(-14LL) == 14LL, ""); +} // namespace abs + namespace fabs { static_assert(__builtin_fabs(-14.0) == 14.0, ""); } _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
