[libc][math] Qualify floor functions to constexpr (#192791)

Signed-off-by: udaykiriti <udaykiriti624@gmail.com>
Co-authored-by: Muhammad Bassiouni <60100307+bassiounix@users.noreply.github.com>

Author: udaykiriti

libc/src/__support/math/floor.h

@@ -15,8 +15,9 @@
 namespace LIBC_NAMESPACE_DECL {
 namespace math {
 
-LIBC_INLINE double floor(double x) {
-#ifdef __LIBC_USE_BUILTIN_CEIL_FLOOR_RINT_TRUNC
+LIBC_INLINE LIBC_CONSTEXPR double floor(double x) {
+#if defined(__LIBC_USE_BUILTIN_CEIL_FLOOR_RINT_TRUNC) &&                       \
+    !defined(LIBC_HAS_CONSTANT_EVALUATION)
   return __builtin_floor(x);
 #else
   return fputil::floor(x);

libc/src/__support/math/floorbf16.h

@@ -16,7 +16,9 @@
 namespace LIBC_NAMESPACE_DECL {
 namespace math {
 
-LIBC_INLINE bfloat16 floorbf16(bfloat16 x) { return fputil::floor(x); }
+LIBC_INLINE constexpr bfloat16 floorbf16(bfloat16 x) {
+  return fputil::floor(x);
+}
 
 } // namespace math
 } // namespace LIBC_NAMESPACE_DECL

libc/src/__support/math/floorf.h

@@ -15,8 +15,9 @@
 namespace LIBC_NAMESPACE_DECL {
 namespace math {
 
-LIBC_INLINE float floorf(float x) {
-#ifdef __LIBC_USE_BUILTIN_CEIL_FLOOR_RINT_TRUNC
+LIBC_INLINE LIBC_CONSTEXPR float floorf(float x) {
+#if defined(__LIBC_USE_BUILTIN_CEIL_FLOOR_RINT_TRUNC) &&                       \
+    !defined(LIBC_HAS_CONSTANT_EVALUATION)
   return __builtin_floorf(x);
 #else
   return fputil::floor(x);

libc/src/__support/math/floorf128.h

@@ -19,7 +19,9 @@
 namespace LIBC_NAMESPACE_DECL {
 namespace math {
 
-LIBC_INLINE float128 floorf128(float128 x) { return fputil::floor(x); }
+LIBC_INLINE constexpr float128 floorf128(float128 x) {
+  return fputil::floor(x);
+}
 
 } // namespace math
 } // namespace LIBC_NAMESPACE_DECL

libc/src/__support/math/floorf16.h

@@ -21,9 +21,10 @@
 namespace LIBC_NAMESPACE_DECL {
 namespace math {
 
-LIBC_INLINE float16 floorf16(float16 x) {
+LIBC_INLINE LIBC_CONSTEXPR float16 floorf16(float16 x) {
 #if defined(__LIBC_USE_BUILTIN_CEIL_FLOOR_RINT_TRUNC) &&                       \
-    defined(LIBC_TARGET_CPU_HAS_FAST_FLOAT16_OPS)
+    defined(LIBC_TARGET_CPU_HAS_FAST_FLOAT16_OPS) &&                           \
+    !defined(LIBC_HAS_CONSTANT_EVALUATION)
   return fputil::cast<float16>(__builtin_floorf(x));
 #else
   return fputil::floor(x);

libc/src/__support/math/floorl.h

@@ -15,7 +15,9 @@
 namespace LIBC_NAMESPACE_DECL {
 namespace math {
 
-LIBC_INLINE long double floorl(long double x) { return fputil::floor(x); }
+LIBC_INLINE constexpr long double floorl(long double x) {
+  return fputil::floor(x);
+}
 
 } // namespace math
 } // namespace LIBC_NAMESPACE_DECL

libc/test/shared/CMakeLists.txt

@@ -290,6 +290,12 @@ add_fp_unittest(
     libc.src.__support.math.copysignf128
     libc.src.__support.math.copysignf16
     libc.src.__support.math.copysignl
+    libc.src.__support.math.floor
+    libc.src.__support.math.floorbf16
+    libc.src.__support.math.floorf
+    libc.src.__support.math.floorf128
+    libc.src.__support.math.floorf16
+    libc.src.__support.math.floorl
     libc.src.__support.math.log
     libc.src.__support.math.logbbf16
 )

libc/test/shared/shared_math_constexpr_test.cpp

@@ -16,15 +16,17 @@
 //===----------------------------------------------------------------------===//
 
 static_assert(0.0 == LIBC_NAMESPACE::shared::ceil(0.0));
-static_assert(0.0 == LIBC_NAMESPACE::shared::log(1.0));
 static_assert(0.0 == LIBC_NAMESPACE::shared::copysign(0.0, 0.0));
+static_assert(1.0 == LIBC_NAMESPACE::shared::floor(1.2));
+static_assert(0.0 == LIBC_NAMESPACE::shared::log(1.0));
 
 //===----------------------------------------------------------------------===//
 //                       Float Tests
 //===----------------------------------------------------------------------===//
 
 static_assert(0.0f == LIBC_NAMESPACE::shared::ceilf(0.0f));
 static_assert(0.0f == LIBC_NAMESPACE::shared::copysignf(0.0f, 0.0f));
+static_assert(0.0f == LIBC_NAMESPACE::shared::floorf(0.0f));
 
 //===----------------------------------------------------------------------===//
 //                       Float16 Tests
@@ -34,6 +36,7 @@ static_assert(0.0f == LIBC_NAMESPACE::shared::copysignf(0.0f, 0.0f));
 
 static_assert(0.0f16 == LIBC_NAMESPACE::shared::ceilf16(0.0f16));
 static_assert(0.0f16 == LIBC_NAMESPACE::shared::copysignf16(0.0f16, 0.0f16));
+static_assert(3.0f16 == LIBC_NAMESPACE::shared::floorf16(3.7f16));
 
 #endif // LIBC_TYPES_HAS_FLOAT16
 
@@ -46,6 +49,7 @@ static_assert(0.0f16 == LIBC_NAMESPACE::shared::copysignf16(0.0f16, 0.0f16));
 
 static_assert(0.0L == LIBC_NAMESPACE::shared::ceill(0.0L));
 static_assert(0.0L == LIBC_NAMESPACE::shared::copysignl(0.0L, 0.0L));
+static_assert(0.0L == LIBC_NAMESPACE::shared::floorl(0.0L));
 
 #endif
 
@@ -60,6 +64,9 @@ static_assert(float128(0.0) ==
               LIBC_NAMESPACE::shared::copysignf128(float128(0.0),
                                                    float128(0.0)));
 
+static_assert(float128(0.0) ==
+              LIBC_NAMESPACE::shared::floorf128(float128(0.0)));
+
 #endif // LIBC_TYPES_HAS_FLOAT128
 
 //===----------------------------------------------------------------------===//
@@ -71,6 +78,8 @@ static_assert(bfloat16(0.0) == LIBC_NAMESPACE::shared::ceilbf16(bfloat16(0.0)));
 static_assert(bfloat16(0.0) ==
               LIBC_NAMESPACE::shared::copysignbf16(bfloat16(0.0),
                                                    bfloat16(0.0)));
+static_assert(bfloat16(0.0) ==
+              LIBC_NAMESPACE::shared::floorbf16(bfloat16(0.0f)));
 static_assert(bfloat16(0.0) ==
               LIBC_NAMESPACE::shared::logbbf16(bfloat16(1.0f)));