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[Clang] Support constexpr builtin fmax 

Support constexpr version of __builtin_fmax and its variations.

Reviewed By: jcranmer-intel

Differential Revision: https://reviews.llvm.org/D134369
This commit is contained in:
Evgeny Shulgin 2022-09-21 15:52:18 +00:00
parent 74ef03d38a
commit 0edff6faa2
3 changed files with 73 additions and 0 deletions
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1
clang/docs/LanguageExtensions.rst
View File

@ -4660,6 +4660,7 @@ The following builtin intrinsics can be used in constant expressions:
* ``__builtin_ffs``
* ``__builtin_ffsl``
* ``__builtin_ffsll``
* ``__builtin_fmax``
* ``__builtin_fpclassify``
* ``__builtin_inf``
* ``__builtin_isinf``

18
clang/lib/AST/ExprConstant.cpp
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@ -14023,6 +14023,24 @@ bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
Result.copySign(RHS);
return true;
}
case Builtin::BI__builtin_fmax:
case Builtin::BI__builtin_fmaxf:
case Builtin::BI__builtin_fmaxl:
case Builtin::BI__builtin_fmaxf16:
case Builtin::BI__builtin_fmaxf128: {
// TODO: Handle sNaN.
APFloat RHS(0.);
if (!EvaluateFloat(E->getArg(0), Result, Info) ||
!EvaluateFloat(E->getArg(1), RHS, Info))
return false;
// When comparing zeroes, return +0.0 if one of the zeroes is positive.
if (Result.isZero() && RHS.isZero() && Result.isNegative())
Result = RHS;
else if (Result.isNaN() || RHS > Result)
Result = RHS;
return true;
}
}
}

54
clang/test/Sema/constant-builtins-fmax.cpp Normal file
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@ -0,0 +1,54 @@
// RUN: %clang_cc1 -fsyntax-only -verify %s
// expected-no-diagnostics
constexpr double NaN = __builtin_nan("");
constexpr double Inf = __builtin_inf();
constexpr double NegInf = -__builtin_inf();
#define FMAX_TEST_SIMPLE(T, FUNC) \
static_assert(T(6.7890) == FUNC(T(1.2345), T(6.7890))); \
static_assert(T(6.7890) == FUNC(T(6.7890), T(1.2345)));
#define FMAX_TEST_NAN(T, FUNC) \
static_assert(Inf == FUNC(NaN, Inf)); \
static_assert(NegInf == FUNC(NegInf, NaN)); \
static_assert(0.0 == FUNC(NaN, 0.0)); \
static_assert(-0.0 == FUNC(-0.0, NaN)); \
static_assert(T(-1.2345) == FUNC(NaN, T(-1.2345))); \
static_assert(T(1.2345) == FUNC(T(1.2345), NaN)); \
static_assert(__builtin_isnan(FUNC(NaN, NaN)));
#define FMAX_TEST_INF(T, FUNC) \
static_assert(Inf == FUNC(NegInf, Inf)); \
static_assert(Inf == FUNC(Inf, 0.0)); \
static_assert(Inf == FUNC(-0.0, Inf)); \
static_assert(Inf == FUNC(Inf, T(1.2345))); \
static_assert(Inf == FUNC(T(-1.2345), Inf));
#define FMAX_TEST_NEG_INF(T, FUNC) \
static_assert(Inf == FUNC(Inf, NegInf)); \
static_assert(0.0 == FUNC(NegInf, 0.0)); \
static_assert(-0.0 == FUNC(-0.0, NegInf)); \
static_assert(T(-1.2345) == FUNC(NegInf, T(-1.2345))); \
static_assert(T(1.2345) == FUNC(T(1.2345), NegInf));
#define FMAX_TEST_BOTH_ZERO(T, FUNC) \
static_assert(__builtin_copysign(1.0, FUNC(0.0, 0.0)) == 1.0); \
static_assert(__builtin_copysign(1.0, FUNC(-0.0, 0.0)) == 1.0); \
static_assert(__builtin_copysign(1.0, FUNC(0.0, -0.0)) == 1.0); \
static_assert(__builtin_copysign(1.0, FUNC(-0.0, -0.0)) == -1.0);
#define LIST_FMAX_TESTS(T, FUNC) \
FMAX_TEST_SIMPLE(T, FUNC) \
FMAX_TEST_NAN(T, FUNC) \
FMAX_TEST_INF(T, FUNC) \
FMAX_TEST_NEG_INF(T, FUNC) \
FMAX_TEST_BOTH_ZERO(T, FUNC)
LIST_FMAX_TESTS(double, __builtin_fmax)
LIST_FMAX_TESTS(float, __builtin_fmaxf)
LIST_FMAX_TESTS((long double), __builtin_fmaxl)
LIST_FMAX_TESTS(__fp16, __builtin_fmaxf16)
#ifdef __FLOAT128__
LIST_FMAX_TESTS(__float128, __builtin_fmaxf128)
#endif