From 1d47a80e1cccb9f7d7c06a3f2a7f0d478c10cbfc Mon Sep 17 00:00:00 2001 From: Kewen12 Date: Wed, 23 Jul 2025 13:28:56 -0700 Subject: [PATCH] Revert "[libc] Make FPUtils' rounding_mode.h functions constexpr. (#149167)" This reverts commit e0a48bb256ffa380d226d9cc50b29196ef587741. --- libc/src/__support/FPUtil/CMakeLists.txt | 1 - libc/src/__support/FPUtil/rounding_mode.h | 67 ++++++++--------------- 2 files changed, 23 insertions(+), 45 deletions(-) diff --git a/libc/src/__support/FPUtil/CMakeLists.txt b/libc/src/__support/FPUtil/CMakeLists.txt index 3024ac62b2951..372eba374d8eb 100644 --- a/libc/src/__support/FPUtil/CMakeLists.txt +++ b/libc/src/__support/FPUtil/CMakeLists.txt @@ -16,7 +16,6 @@ add_header_library( rounding_mode.h DEPENDS libc.hdr.fenv_macros - libc.src.__support.CPP.type_traits libc.src.__support.macros.attributes libc.src.__support.macros.properties.architectures libc.src.__support.macros.sanitizer diff --git a/libc/src/__support/FPUtil/rounding_mode.h b/libc/src/__support/FPUtil/rounding_mode.h index 4ee0a0b0490fc..bc66d09b94160 100644 --- a/libc/src/__support/FPUtil/rounding_mode.h +++ b/libc/src/__support/FPUtil/rounding_mode.h @@ -10,7 +10,6 @@ #define LLVM_LIBC_SRC___SUPPORT_FPUTIL_ROUNDING_MODE_H #include "hdr/fenv_macros.h" -#include "src/__support/CPP/type_traits.h" // is_constant_evaluated #include "src/__support/macros/attributes.h" // LIBC_INLINE #include "src/__support/macros/config.h" @@ -21,26 +20,18 @@ namespace fputil { // Using the following observation: // 1.0f + 2^-25 = 1.0f for FE_TONEAREST, FE_DOWNWARD, FE_TOWARDZERO // = 0x1.000002f for FE_UPWARD. -LIBC_INLINE static constexpr bool fenv_is_round_up() { - if (cpp::is_constant_evaluated()) { - return false; - } else { - volatile float x = 0x1.0p-25f; - return (1.0f + x != 1.0f); - } +LIBC_INLINE bool fenv_is_round_up() { + volatile float x = 0x1.0p-25f; + return (1.0f + x != 1.0f); } // Quick free-standing test whether fegetround() == FE_DOWNWARD. // Using the following observation: // -1.0f - 2^-25 = -1.0f for FE_TONEAREST, FE_UPWARD, FE_TOWARDZERO // = -0x1.000002f for FE_DOWNWARD. -LIBC_INLINE static constexpr bool fenv_is_round_down() { - if (cpp::is_constant_evaluated()) { - return false; - } else { - volatile float x = 0x1.0p-25f; - return (-1.0f - x != -1.0f); - } +LIBC_INLINE bool fenv_is_round_down() { + volatile float x = 0x1.0p-25f; + return (-1.0f - x != -1.0f); } // Quick free-standing test whether fegetround() == FE_TONEAREST. @@ -49,14 +40,10 @@ LIBC_INLINE static constexpr bool fenv_is_round_down() { // = 0x1.100002p0f for FE_UPWARD, // 1.5f - 2^-24 = 1.5f for FE_TONEAREST, FE_UPWARD // = 0x1.0ffffep-1f for FE_DOWNWARD, FE_TOWARDZERO -LIBC_INLINE static constexpr bool fenv_is_round_to_nearest() { - if (cpp::is_constant_evaluated()) { - return true; - } else { - volatile float x = 0x1.0p-24f; - float y = 1.5f + x; - return (y == 1.5f - x); - } +LIBC_INLINE bool fenv_is_round_to_nearest() { + static volatile float x = 0x1.0p-24f; + float y = x; + return (1.5f + y == 1.5f - y); } // Quick free-standing test whether fegetround() == FE_TOWARDZERO. @@ -69,31 +56,23 @@ LIBC_INLINE static constexpr bool fenv_is_round_to_nearest() { // (0x1.000002p0f + 2^-24) + (-1.0f - 2^-24) = 2^-23 for FE_TOWARDZERO // = 2^-22 for FE_TONEAREST, FE_UPWARD // = 0 for FE_DOWNWARD -LIBC_INLINE static constexpr bool fenv_is_round_to_zero() { - if (cpp::is_constant_evaluated()) { - return false; - } else { - volatile float x = 0x1.0p-24f; - volatile float y = 0x1.000002p0f + x; - return (y + (-1.0f - x) == 0x1.0p-23f); - } +LIBC_INLINE bool fenv_is_round_to_zero() { + static volatile float x = 0x1.0p-24f; + float y = x; + return ((0x1.000002p0f + y) + (-1.0f - y) == 0x1.0p-23f); } // Quick free standing get rounding mode based on the above observations. -LIBC_INLINE static constexpr int quick_get_round() { - if (cpp::is_constant_evaluated()) { - return FE_TONEAREST; - } else { - volatile float x = 0x1.0p-24f; - volatile float y = 0x1.000002p0f + x; - float z = y + (-1.0f - x); +LIBC_INLINE int quick_get_round() { + static volatile float x = 0x1.0p-24f; + float y = x; + float z = (0x1.000002p0f + y) + (-1.0f - y); - if (z == 0.0f) - return FE_DOWNWARD; - if (z == 0x1.0p-23f) - return FE_TOWARDZERO; - return (2.0f + x == 2.0f) ? FE_TONEAREST : FE_UPWARD; - } + if (z == 0.0f) + return FE_DOWNWARD; + if (z == 0x1.0p-23f) + return FE_TOWARDZERO; + return (2.0f + y == 2.0f) ? FE_TONEAREST : FE_UPWARD; } } // namespace fputil