[libc-commits] [libc] [libc][math] Implement nearest integer functions using builtins when available (PR #98376)

Wed Jul 10 13:15:01 PDT 2024

llvmbot wrote:




@llvm/pr-subscribers-libc

Author: OverMighty (overmighty)

<details>
<summary>Changes</summary>



---

Patch is 34.78 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/98376.diff


27 Files Affected:

- (modified) libc/cmake/modules/CheckCompilerFeatures.cmake (+24-2) 
- (modified) libc/cmake/modules/LLVMLibCCompileOptionRules.cmake (+17-3) 
- (modified) libc/cmake/modules/LLVMLibCFlagRules.cmake (+2-1) 
- (added) libc/cmake/modules/compiler_features/check_builtin_ceil_floor_trunc.cpp (+9) 
- (added) libc/cmake/modules/compiler_features/check_builtin_round.cpp (+5) 
- (added) libc/cmake/modules/compiler_features/check_builtin_roundeven.cpp (+5) 
- (modified) libc/config/linux/aarch64/entrypoints.txt (+1) 
- (modified) libc/src/__support/FPUtil/NearestIntegerOperations.h (+21-16) 
- (modified) libc/src/math/generic/CMakeLists.txt (+35) 
- (modified) libc/src/math/generic/ceil.cpp (+7-1) 
- (modified) libc/src/math/generic/ceilf.cpp (+7-1) 
- (modified) libc/src/math/generic/ceilf16.cpp (+9-1) 
- (modified) libc/src/math/generic/floor.cpp (+7-1) 
- (modified) libc/src/math/generic/floorf.cpp (+7-1) 
- (modified) libc/src/math/generic/floorf16.cpp (+9-1) 
- (modified) libc/src/math/generic/round.cpp (+7-1) 
- (modified) libc/src/math/generic/roundeven.cpp (+4) 
- (modified) libc/src/math/generic/roundevenf.cpp (+4) 
- (modified) libc/src/math/generic/roundevenf16.cpp (+6) 
- (modified) libc/src/math/generic/roundf.cpp (+7-1) 
- (modified) libc/src/math/generic/roundf16.cpp (+8-1) 
- (modified) libc/src/math/generic/trunc.cpp (+7-1) 
- (modified) libc/src/math/generic/truncf.cpp (+7-1) 
- (modified) libc/src/math/generic/truncf16.cpp (+9-1) 
- (modified) libc/test/src/math/performance_testing/CMakeLists.txt (+19) 
- (added) libc/test/src/math/performance_testing/NearestIntegerPerf.h (+110) 
- (added) libc/test/src/math/performance_testing/nearest_integer_funcs_perf.cpp (+165) 


``````````diff

diff --git a/libc/cmake/modules/CheckCompilerFeatures.cmake b/libc/cmake/modules/CheckCompilerFeatures.cmake
index d84c07b35d2d7..83822892c8096 100644
--- a/libc/cmake/modules/CheckCompilerFeatures.cmake
+++ b/libc/cmake/modules/CheckCompilerFeatures.cmake
@@ -2,7 +2,15 @@
 # Compiler features definition and flags
 # ------------------------------------------------------------------------------
 
-set(ALL_COMPILER_FEATURES "float16" "float128" "fixed_point")
+set(
+  ALL_COMPILER_FEATURES
+    "builtin_ceil_floor_trunc"
+    "builtin_round"
+    "builtin_roundeven"
+    "float16"
+    "float128"
+    "fixed_point"
+)
 
 # Making sure ALL_COMPILER_FEATURES is sorted.
 list(SORT ALL_COMPILER_FEATURES)
@@ -39,11 +47,19 @@ endfunction()
 set(AVAILABLE_COMPILER_FEATURES "")
 
 # Try compile a C file to check if flag is supported.
-set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
 foreach(feature IN LISTS ALL_COMPILER_FEATURES)
+  set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
   set(compile_options ${LIBC_COMPILE_OPTIONS_NATIVE})
   if(${feature} STREQUAL "fixed_point")
     list(APPEND compile_options "-ffixed-point")
+  elseif(${feature} MATCHES "^builtin_")
+    set(compile_options ${LIBC_COMPILE_OPTIONS_DEFAULT})
+    # The compiler might handle calls to rounding builtins by generating calls
+    # to the respective libc math functions, in which case we cannot use these
+    # builtins in our implementations of these functions. We check that this is
+    # not the case by trying to link an executable, since linking would fail due
+    # to unresolved references if calls to libc functions were generated.
+    set(CMAKE_TRY_COMPILE_TARGET_TYPE EXECUTABLE)
   endif()
 
   try_compile(
@@ -60,6 +76,12 @@ foreach(feature IN LISTS ALL_COMPILER_FEATURES)
       set(LIBC_TYPES_HAS_FLOAT128 TRUE)
     elseif(${feature} STREQUAL "fixed_point")
       set(LIBC_COMPILER_HAS_FIXED_POINT TRUE)
+    elseif(${feature} STREQUAL "builtin_ceil_floor_trunc")
+      set(LIBC_COMPILER_HAS_BUILTIN_CEIL_FLOOR_TRUNC TRUE)
+    elseif(${feature} STREQUAL "builtin_round")
+      set(LIBC_COMPILER_HAS_BUILTIN_ROUND TRUE)
+    elseif(${feature} STREQUAL "builtin_roundeven")
+      set(LIBC_COMPILER_HAS_BUILTIN_ROUNDEVEN TRUE)
     endif()
   endif()
 endforeach()
diff --git a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
index c5e7dfe8abd0f..855d69d2a0fc9 100644
--- a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
+++ b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
@@ -4,7 +4,7 @@ function(_get_compile_options_from_flags output_var)
   if(LIBC_TARGET_ARCHITECTURE_IS_RISCV64 OR(LIBC_CPU_FEATURES MATCHES "FMA"))
     check_flag(ADD_FMA_FLAG ${FMA_OPT_FLAG} ${ARGN})
   endif()
-  check_flag(ADD_SSE4_2_FLAG ${ROUND_OPT_FLAG} ${ARGN})
+  check_flag(ADD_ROUND_OPT_FLAG ${ROUND_OPT_FLAG} ${ARGN})
   check_flag(ADD_EXPLICIT_SIMD_OPT_FLAG ${EXPLICIT_SIMD_OPT_FLAG} ${ARGN})
 
   if(LLVM_COMPILER_IS_GCC_COMPATIBLE)
@@ -16,8 +16,22 @@ function(_get_compile_options_from_flags output_var)
         list(APPEND compile_options "-D__LIBC_RISCV_USE_FMA")
       endif()
     endif()
-    if(ADD_SSE4_2_FLAG)
-      list(APPEND compile_options "-msse4.2")
+    if(ADD_ROUND_OPT_FLAG)
+      if(LIBC_TARGET_ARCHITECTURE_IS_X86)
+        # ROUND_OPT_FLAG is only enabled if SSE4.2 is detected, not just SSE4.1,
+        # because there was code to check for SSE4.2 already, and few CPUs only
+        # have SSE4.1.
+        list(APPEND compile_options "-msse4.2")
+      endif()
+      if(LIBC_COMPILER_HAS_BUILTIN_CEIL_FLOOR_TRUNC)
+        list(APPEND compile_options "-D__LIBC_USE_BUILTIN_CEIL_FLOOR_TRUNC")
+      endif()
+      if(LIBC_COMPILER_HAS_BUILTIN_ROUND)
+        list(APPEND compile_options "-D__LIBC_USE_BUILTIN_ROUND")
+      endif()
+      if(LIBC_COMPILER_HAS_BUILTIN_ROUNDEVEN)
+        list(APPEND compile_options "-D__LIBC_USE_BUILTIN_ROUNDEVEN")
+      endif()
     endif()
     if(ADD_EXPLICIT_SIMD_OPT_FLAG)
       list(APPEND compile_options "-D__LIBC_EXPLICIT_SIMD_OPT")
diff --git a/libc/cmake/modules/LLVMLibCFlagRules.cmake b/libc/cmake/modules/LLVMLibCFlagRules.cmake
index 18e36dfde5cc1..eca7ba8d183e6 100644
--- a/libc/cmake/modules/LLVMLibCFlagRules.cmake
+++ b/libc/cmake/modules/LLVMLibCFlagRules.cmake
@@ -277,6 +277,7 @@ if(NOT(LIBC_TARGET_ARCHITECTURE_IS_X86 AND (LIBC_CPU_FEATURES MATCHES "SSE2")))
 endif()
 
 # Skip ROUND_OPT flag for targets that don't support SSE 4.2.
-if(NOT(LIBC_TARGET_ARCHITECTURE_IS_X86 AND (LIBC_CPU_FEATURES MATCHES "SSE4_2")))
+if(NOT((LIBC_TARGET_ARCHITECTURE_IS_X86 AND (LIBC_CPU_FEATURES MATCHES "SSE4_2")) OR
+       LIBC_TARGET_ARCHITECTURE_IS_AARCH64))
   set(SKIP_FLAG_EXPANSION_ROUND_OPT TRUE)
 endif()
diff --git a/libc/cmake/modules/compiler_features/check_builtin_ceil_floor_trunc.cpp b/libc/cmake/modules/compiler_features/check_builtin_ceil_floor_trunc.cpp
new file mode 100644
index 0000000000000..031dd9376f3c1
--- /dev/null
+++ b/libc/cmake/modules/compiler_features/check_builtin_ceil_floor_trunc.cpp
@@ -0,0 +1,9 @@
+float try_builtin_ceilf(float x) { return __builtin_ceilf(x); }
+float try_builtin_floorf(float x) { return __builtin_ceilf(x); }
+float try_builtin_truncf(float x) { return __builtin_truncf(x); }
+
+double try_builtin_ceil(double x) { return __builtin_ceil(x); }
+double try_builtin_floor(double x) { return __builtin_ceil(x); }
+double try_builtin_trunc(double x) { return __builtin_trunc(x); }
+
+int main() {}
diff --git a/libc/cmake/modules/compiler_features/check_builtin_round.cpp b/libc/cmake/modules/compiler_features/check_builtin_round.cpp
new file mode 100644
index 0000000000000..8c3065c2de06a
--- /dev/null
+++ b/libc/cmake/modules/compiler_features/check_builtin_round.cpp
@@ -0,0 +1,5 @@
+float try_builtin_roundf(float x) { return __builtin_roundf(x); }
+
+double try_builtin_round(double x) { return __builtin_round(x); }
+
+int main() {}
diff --git a/libc/cmake/modules/compiler_features/check_builtin_roundeven.cpp b/libc/cmake/modules/compiler_features/check_builtin_roundeven.cpp
new file mode 100644
index 0000000000000..2480abae84c36
--- /dev/null
+++ b/libc/cmake/modules/compiler_features/check_builtin_roundeven.cpp
@@ -0,0 +1,5 @@
+float try_builtin_roundevenf(float x) { return __builtin_roundevenf(x); }
+
+double try_builtin_roundeven(double x) { return __builtin_roundeven(x); }
+
+int main() {}
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 030c3d3a99a02..515c472ef309e 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -489,6 +489,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.rintl
     libc.src.math.round
     libc.src.math.roundf
+    libc.src.math.roundevenf
     libc.src.math.roundl
     libc.src.math.scalbn
     libc.src.math.scalbnf
diff --git a/libc/src/__support/FPUtil/NearestIntegerOperations.h b/libc/src/__support/FPUtil/NearestIntegerOperations.h
index cff32938229d0..a9a0a97eebb5c 100644
--- a/libc/src/__support/FPUtil/NearestIntegerOperations.h
+++ b/libc/src/__support/FPUtil/NearestIntegerOperations.h
@@ -75,15 +75,17 @@ LIBC_INLINE T ceil(T x) {
   }
 
   uint32_t trim_size = FPBits<T>::FRACTION_LEN - exponent;
-  StorageType trunc_mantissa =
-      static_cast<StorageType>((bits.get_mantissa() >> trim_size) << trim_size);
-  bits.set_mantissa(trunc_mantissa);
-  T trunc_value = bits.get_val();
+  StorageType x_u = bits.uintval();
+  StorageType trunc_u =
+      static_cast<StorageType>((x_u >> trim_size) << trim_size);
 
   // If x is already an integer, return it.
-  if (trunc_value == x)
+  if (trunc_u == x_u)
     return x;
 
+  bits.set_uintval(trunc_u);
+  T trunc_value = bits.get_val();
+
   // If x is negative, the ceil operation is equivalent to the trunc operation.
   if (is_neg)
     return trunc_value;
@@ -130,15 +132,17 @@ LIBC_INLINE T round(T x) {
   uint32_t trim_size = FPBits<T>::FRACTION_LEN - exponent;
   bool half_bit_set =
       bool(bits.get_mantissa() & (StorageType(1) << (trim_size - 1)));
-  StorageType trunc_mantissa =
-      static_cast<StorageType>((bits.get_mantissa() >> trim_size) << trim_size);
-  bits.set_mantissa(trunc_mantissa);
-  T trunc_value = bits.get_val();
+  StorageType x_u = bits.uintval();
+  StorageType trunc_u =
+      static_cast<StorageType>((x_u >> trim_size) << trim_size);
 
   // If x is already an integer, return it.
-  if (trunc_value == x)
+  if (trunc_u == x_u)
     return x;
 
+  bits.set_uintval(trunc_u);
+  T trunc_value = bits.get_val();
+
   if (!half_bit_set) {
     // Franctional part is less than 0.5 so round value is the
     // same as the trunc value.
@@ -188,16 +192,17 @@ round_using_specific_rounding_mode(T x, int rnd) {
   }
 
   uint32_t trim_size = FPBits<T>::FRACTION_LEN - exponent;
-  FPBits<T> new_bits = bits;
-  StorageType trunc_mantissa =
-      static_cast<StorageType>((bits.get_mantissa() >> trim_size) << trim_size);
-  new_bits.set_mantissa(trunc_mantissa);
-  T trunc_value = new_bits.get_val();
+  StorageType x_u = bits.uintval();
+  StorageType trunc_u =
+      static_cast<StorageType>((x_u >> trim_size) << trim_size);
 
   // If x is already an integer, return it.
-  if (trunc_value == x)
+  if (trunc_u == x_u)
     return x;
 
+  FPBits<T> new_bits(trunc_u);
+  T trunc_value = new_bits.get_val();
+
   StorageType trim_value =
       bits.get_mantissa() &
       static_cast<StorageType>(((StorageType(1) << trim_size) - 1));
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index 5e920307d39de..915fc076826f9 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -70,6 +70,8 @@ add_entrypoint_object(
     -O3
   DEPENDS
     libc.src.__support.FPUtil.nearest_integer_operations
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -82,6 +84,8 @@ add_entrypoint_object(
     -O3
   DEPENDS
     libc.src.__support.FPUtil.nearest_integer_operations
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -107,6 +111,9 @@ add_entrypoint_object(
   DEPENDS
     libc.src.__support.macros.properties.types
     libc.src.__support.FPUtil.nearest_integer_operations
+    libc.src.__support.macros.properties.architectures
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -455,6 +462,8 @@ add_entrypoint_object(
     -O3
   DEPENDS
     libc.src.__support.FPUtil.nearest_integer_operations
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -467,6 +476,8 @@ add_entrypoint_object(
     -O3
   DEPENDS
     libc.src.__support.FPUtil.nearest_integer_operations
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -492,6 +503,9 @@ add_entrypoint_object(
   DEPENDS
     libc.src.__support.macros.properties.types
     libc.src.__support.FPUtil.nearest_integer_operations
+    libc.src.__support.macros.properties.architectures
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -517,6 +531,8 @@ add_entrypoint_object(
     -O3
   DEPENDS
     libc.src.__support.FPUtil.nearest_integer_operations
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -529,6 +545,8 @@ add_entrypoint_object(
     -O3
   DEPENDS
     libc.src.__support.FPUtil.nearest_integer_operations
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -554,6 +572,9 @@ add_entrypoint_object(
   DEPENDS
     libc.src.__support.macros.properties.types
     libc.src.__support.FPUtil.nearest_integer_operations
+    libc.src.__support.macros.properties.architectures
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -579,6 +600,8 @@ add_entrypoint_object(
     -O3
   DEPENDS
     libc.src.__support.FPUtil.nearest_integer_operations
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -591,6 +614,8 @@ add_entrypoint_object(
     -O3
   DEPENDS
     libc.src.__support.FPUtil.nearest_integer_operations
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -616,6 +641,9 @@ add_entrypoint_object(
   DEPENDS
     libc.src.__support.macros.properties.types
     libc.src.__support.FPUtil.nearest_integer_operations
+    libc.src.__support.macros.properties.architectures
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -641,6 +669,8 @@ add_entrypoint_object(
     -O3
   DEPENDS
     libc.src.__support.FPUtil.nearest_integer_operations
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -653,6 +683,8 @@ add_entrypoint_object(
     -O3
   DEPENDS
     libc.src.__support.FPUtil.nearest_integer_operations
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
@@ -678,6 +710,9 @@ add_entrypoint_object(
   DEPENDS
     libc.src.__support.macros.properties.types
     libc.src.__support.FPUtil.nearest_integer_operations
+    libc.src.__support.macros.properties.architectures
+  FLAGS
+    ROUND_OPT
 )
 
 add_entrypoint_object(
diff --git a/libc/src/math/generic/ceil.cpp b/libc/src/math/generic/ceil.cpp
index efd0f246a9b90..63da803033e22 100644
--- a/libc/src/math/generic/ceil.cpp
+++ b/libc/src/math/generic/ceil.cpp
@@ -12,6 +12,12 @@
 
 namespace LIBC_NAMESPACE {
 
-LLVM_LIBC_FUNCTION(double, ceil, (double x)) { return fputil::ceil(x); }
+LLVM_LIBC_FUNCTION(double, ceil, (double x)) {
+#ifdef __LIBC_USE_BUILTIN_CEIL_FLOOR_TRUNC
+  return __builtin_ceil(x);
+#else
+  return fputil::ceil(x);
+#endif
+}
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/ceilf.cpp b/libc/src/math/generic/ceilf.cpp
index d49b34242da4f..51ef68f1dd871 100644
--- a/libc/src/math/generic/ceilf.cpp
+++ b/libc/src/math/generic/ceilf.cpp
@@ -12,6 +12,12 @@
 
 namespace LIBC_NAMESPACE {
 
-LLVM_LIBC_FUNCTION(float, ceilf, (float x)) { return fputil::ceil(x); }
+LLVM_LIBC_FUNCTION(float, ceilf, (float x)) {
+#ifdef __LIBC_USE_BUILTIN_CEIL_FLOOR_TRUNC
+  return __builtin_ceilf(x);
+#else
+  return fputil::ceil(x);
+#endif
+}
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/ceilf16.cpp b/libc/src/math/generic/ceilf16.cpp
index 205d7428f66e6..ee584c25a4ae9 100644
--- a/libc/src/math/generic/ceilf16.cpp
+++ b/libc/src/math/generic/ceilf16.cpp
@@ -9,9 +9,17 @@
 #include "src/math/ceilf16.h"
 #include "src/__support/FPUtil/NearestIntegerOperations.h"
 #include "src/__support/common.h"
+#include "src/__support/macros/properties/architectures.h"
 
 namespace LIBC_NAMESPACE {
 
-LLVM_LIBC_FUNCTION(float16, ceilf16, (float16 x)) { return fputil::ceil(x); }
+LLVM_LIBC_FUNCTION(float16, ceilf16, (float16 x)) {
+#if defined(__LIBC_USE_BUILTIN_CEIL_FLOOR_TRUNC) &&                            \
+    defined(LIBC_TARGET_ARCH_IS_AARCH64)
+  return static_cast<float16>(__builtin_ceilf(x));
+#else
+  return fputil::ceil(x);
+#endif
+}
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/floor.cpp b/libc/src/math/generic/floor.cpp
index 60386f0c9cf81..bb58ca6a35402 100644
--- a/libc/src/math/generic/floor.cpp
+++ b/libc/src/math/generic/floor.cpp
@@ -12,6 +12,12 @@
 
 namespace LIBC_NAMESPACE {
 
-LLVM_LIBC_FUNCTION(double, floor, (double x)) { return fputil::floor(x); }
+LLVM_LIBC_FUNCTION(double, floor, (double x)) {
+#ifdef __LIBC_USE_BUILTIN_CEIL_FLOOR_TRUNC
+  return __builtin_floor(x);
+#else
+  return fputil::floor(x);
+#endif
+}
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/floorf.cpp b/libc/src/math/generic/floorf.cpp
index 85666688685dc..459f338d897be 100644
--- a/libc/src/math/generic/floorf.cpp
+++ b/libc/src/math/generic/floorf.cpp
@@ -12,6 +12,12 @@
 
 namespace LIBC_NAMESPACE {
 
-LLVM_LIBC_FUNCTION(float, floorf, (float x)) { return fputil::floor(x); }
+LLVM_LIBC_FUNCTION(float, floorf, (float x)) {
+#ifdef __LIBC_USE_BUILTIN_CEIL_FLOOR_TRUNC
+  return __builtin_floorf(x);
+#else
+  return fputil::floor(x);
+#endif
+}
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/floorf16.cpp b/libc/src/math/generic/floorf16.cpp
index db0b326c0e5f6..6d8c497946c84 100644
--- a/libc/src/math/generic/floorf16.cpp
+++ b/libc/src/math/generic/floorf16.cpp
@@ -9,9 +9,17 @@
 #include "src/math/floorf16.h"
 #include "src/__support/FPUtil/NearestIntegerOperations.h"
 #include "src/__support/common.h"
+#include "src/__support/macros/properties/architectures.h"
 
 namespace LIBC_NAMESPACE {
 
-LLVM_LIBC_FUNCTION(float16, floorf16, (float16 x)) { return fputil::floor(x); }
+LLVM_LIBC_FUNCTION(float16, floorf16, (float16 x)) {
+#if defined(__LIBC_USE_BUILTIN_CEIL_FLOOR_TRUNC) &&                            \
+    defined(LIBC_TARGET_ARCH_IS_AARCH64)
+  return static_cast<float16>(__builtin_floorf(x));
+#else
+  return fputil::floor(x);
+#endif
+}
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/round.cpp b/libc/src/math/generic/round.cpp
index ca8f19f35f7fe..d873524ad9f42 100644
--- a/libc/src/math/generic/round.cpp
+++ b/libc/src/math/generic/round.cpp
@@ -12,6 +12,12 @@
 
 namespace LIBC_NAMESPACE {
 
-LLVM_LIBC_FUNCTION(double, round, (double x)) { return fputil::round(x); }
+LLVM_LIBC_FUNCTION(double, round, (double x)) {
+#ifdef __LIBC_USE_BUILTIN_ROUND
+  return __builtin_round(x);
+#else
+  return fputil::round(x);
+#endif
+}
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/roundeven.cpp b/libc/src/math/generic/roundeven.cpp
index 5f2adf9b5fce6..76409d526e208 100644
--- a/libc/src/math/generic/roundeven.cpp
+++ b/libc/src/math/generic/roundeven.cpp
@@ -13,7 +13,11 @@
 namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(double, roundeven, (double x)) {
+#ifdef __LIBC_USE_BUILTIN_ROUNDEVEN
+  return __builtin_roundeven(x);
+#else
   return fputil::round_using_specific_rounding_mode(x, FP_INT_TONEAREST);
+#endif
 }
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/roundevenf.cpp b/libc/src/math/generic/roundevenf.cpp
index 353bec74ecf02..22538272bedbd 100644
--- a/libc/src/math/generic/roundevenf.cpp
+++ b/libc/src/math/generic/roundevenf.cpp
@@ -13,7 +13,11 @@
 namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(float, roundevenf, (float x)) {
+#ifdef __LIBC_USE_BUILTIN_ROUNDEVEN
+  return __builtin_roundevenf(x);
+#else
   return fputil::round_using_specific_rounding_mode(x, FP_INT_TONEAREST);
+#endif
 }
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/roundevenf16.cpp b/libc/src/math/generic/roundevenf16.cpp
index 9ecf79ce6f6c2..90c75a10d3ddb 100644
--- a/libc/src/math/generic/roundevenf16.cpp
+++ b/libc/src/math/generic/roundevenf16.cpp
@@ -9,11 +9,17 @@
 #include "src/math/roundevenf16.h"
 #include "src/__support/FPUtil/NearestIntegerOperations.h"
 #include "src/__support/common.h"
+#include "src/__support/macros/properties/architectures.h"
 
 namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(float16, roundevenf16, (float16 x)) {
+#if defined(__LIBC_USE_BUILTIN_ROUNDEVEN) &&                                   \
+    defined(LIBC_TARGET_ARCH_IS_AARCH64)
+  return static_cast<float16>(__builtin_roundevenf(x));
+#else
   return fputil::round_using_specific_rounding_mode(x, FP_INT_TONEAREST);
+#endif
 }
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/roundf.cpp b/libc/src/math/generic/roundf.cpp
index 9627390ea8b8d..8b3add7cb9e2d 100644
--- a/libc/src/math/generic/roundf.cpp
+++ b/libc/src/math/generic/roundf.cpp
@@ -12,6 +12,12 @@
 
 namespace LIBC_NAMESPACE {
 
-LLVM_LIBC_FUNCTION(float, roundf, (float x)) { return fputil::round(x); }
+LLVM_LIBC_FUNCTION(float, roundf, (float x)) {
+#ifdef __LIBC_USE_BUILTIN_ROUND
+  return __builtin_roundf(x);
+#else
+  return fputil::round(x);
+#endif
+}
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/roundf16.cpp b/libc/src/math/generic/roundf16.cpp
index 75a255d7798d5..fca0194ec5dbb 100644
--- a/libc/src/math/generic/roundf16.cpp
+++ b/libc/src/math/generic/roundf16.cpp
@@ -9,9 +9,16 @@
 #include "src/math/roundf16.h"
 #include "src/__support/FPUtil/NearestIntegerOperations.h"
 #include "src/__support/common.h"
+#include "src/__support/macros/properties/architectures.h"
 
 namespace LIBC_NAMESPACE {
 
-LLVM_LIBC_FUNCTION(float16, roundf16, (float16 x)) { return fputil::round(x); }
+LLVM_LIBC_FUNCTION(float16, roundf16, (float16 x)) {
+#if defined(__LIBC_USE_BUILTIN_ROUND) && defined(LIBC_TARGET_ARCH_IS_AARCH64)
+  return static_cast<float16>(__builtin_roundf(x));
+#else
+  return fputil::round(x);
+#endif
+}
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/trunc.cpp b/libc/src/math/generic/trunc.cpp
index d171ab1f092fd..5761565646c36 100644
--- a/libc/src/math/generic/trunc.cpp
+++ b/libc/src/math/generic/trunc.cpp
@@ -12,6 +12,12 @@
 
 namespace L...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/98376
