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[libc] Make LIBC_MATH_NO_ERRNO imply -fno-math-errno #125794

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Merged
merged 4 commits into from
Oct 16, 2025
Merged

[libc] Make LIBC_MATH_NO_ERRNO imply -fno-math-errno #125794

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6d9dac2
[libc] Make LIBC_MATH_NO_ERRNO imply `-fno-math-errno`
petrhosek Feb 5, 2025
92a0fd5
Move the check
petrhosek Feb 5, 2025
5688536
Merge remote-tracking branch 'origin/main' into libc-config-no-math-e…
petrhosek Oct 15, 2025
18520d4
Readd the null check
petrhosek Oct 15, 2025
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10 changes: 3 additions & 7 deletions libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -26,13 +26,6 @@ function(_get_compile_options_from_flags output_var)
list(APPEND compile_options "-mavx2")
list(APPEND compile_options "-mfma")
endif()
# For clang, we will build the math functions with `-fno-math-errno` so that
# __builtin_fma* will generate the fused-mutliply-add instructions. We
# don't put the control flag to the public config yet, and see if it makes
# sense to just enable this flag by default.
if(LIBC_ADD_FNO_MATH_ERRNO)
list(APPEND compile_options "-fno-math-errno")
endif()
endif()
if(ADD_ROUND_OPT_FLAG)
if(LIBC_TARGET_ARCHITECTURE_IS_X86_64)
Expand Down Expand Up @@ -102,6 +95,9 @@ function(_get_compile_options_from_config output_var)

if(LIBC_CONF_MATH_OPTIMIZATIONS)
list(APPEND config_options "-DLIBC_MATH=${LIBC_CONF_MATH_OPTIMIZATIONS}")
if(LIBC_CONF_MATH_OPTIMIZATIONS MATCHES "LIBC_MATH_NO_ERRNO")
list(APPEND config_options "-fno-math-errno")
endif()
endif()

if(LIBC_CONF_ERRNO_MODE)
Expand Down
5 changes: 0 additions & 5 deletions libc/cmake/modules/LLVMLibCTestRules.cmake
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Expand Up @@ -3,11 +3,6 @@ function(_get_common_test_compile_options output_var c_test flags)
_get_compile_options_from_config(config_flags)
_get_compile_options_from_arch(arch_flags)

# Remove -fno-math-errno if it was added.
if(LIBC_ADD_FNO_MATH_ERRNO)
list(REMOVE_ITEM compile_flags "-fno-math-errno")
endif()

# Death test executor is only available in Linux for now.
if(NOT ${LIBC_TARGET_OS} STREQUAL "linux")
list(REMOVE_ITEM config_flags "-DLIBC_ADD_NULL_CHECKS")
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2 changes: 1 addition & 1 deletion libc/config/baremetal/config.json
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Expand Up @@ -36,7 +36,7 @@
},
"math": {
"LIBC_CONF_MATH_OPTIMIZATIONS": {
"value": "(LIBC_MATH_SKIP_ACCURATE_PASS | LIBC_MATH_SMALL_TABLES)"
"value": "(LIBC_MATH_SKIP_ACCURATE_PASS | LIBC_MATH_SMALL_TABLES | LIBC_MATH_NO_ERRNO)"
}
},
"general": {
Expand Down
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