[libc-commits] [libc] [llvm] [libc][math] Refactor fmaximum_mag_num family to header-only (PR #182169)

Sat Apr 25 15:11:16 PDT 2026

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `libc-aarch64-ubuntu-fullbuild-dbg` running on `libc-aarch64-ubuntu` while building `libc,utils` at step 4 "annotate".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/71/builds/46755

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 4 (annotate) failure: 'python ../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py ...' (failure)
...
[78/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.fma.dir/fma.cpp.o
[79/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.canonicalizef.dir/canonicalizef.cpp.o
[80/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.fabsf128.__internal__.dir/fabsf128.cpp.o
[81/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.llroundbf16.dir/llroundbf16.cpp.o
[82/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.fmaximumf.__NO_MISC_MATH_BASIC_OPS_OPT.__internal__.dir/fmaximumf.cpp.o
[83/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.fromfpxbf16.dir/fromfpxbf16.cpp.o
[84/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.nextupbf16.__internal__.dir/nextupbf16.cpp.o
[85/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.asinbf16.dir/asinbf16.cpp.o
[86/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.fminimum_numf128.__internal__.dir/fminimum_numf128.cpp.o
[87/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.fmaximumf.dir/fmaximumf.cpp.o
FAILED: libc/src/math/generic/CMakeFiles/libc.src.math.generic.fmaximumf.dir/fmaximumf.cpp.o 
/usr/bin/clang++ -DLIBC_NAMESPACE=__llvm_libc_20_0_0_git -D_DEBUG -I/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc -isystem libc/include -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wstring-conversion -Wno-pass-failed -fdiagnostics-color -g -D__LIBC_MISC_MATH_BASIC_OPS_OPT -D__LIBC_USE_BUILTIN_FMAX_FMIN -D__LIBC_USE_BUILTIN_FMAXF16_FMINF16 -Xclang -target-feature -Xclang +fullfp16 -DLIBC_QSORT_IMPL=LIBC_QSORT_QUICK_SORT -DLIBC_COPT_STRING_LENGTH_IMPL=clang_vector -DLIBC_COPT_FIND_FIRST_CHARACTER_IMPL=word -DLIBC_ADD_NULL_CHECKS -DLIBC_ERRNO_MODE=LIBC_ERRNO_MODE_DEFAULT -DLIBC_THREAD_MODE=LIBC_THREAD_MODE_PLATFORM -DLIBC_COPT_TIMEOUT_ENSURE_MONOTONICITY -DLIBC_CONF_WCTYPE_MODE=LIBC_WCTYPE_MODE_ASCII -DLIBC_COPT_RAW_MUTEX_DEFAULT_SPIN_COUNT=100 -fpie -ffreestanding -DLIBC_FULL_BUILD -nostdlibinc -idirafter/usr/include -fno-builtin -fno-exceptions -fno-lax-vector-conversions -fno-unwind-tables -fno-asynchronous-unwind-tables -fno-rtti -ftrivial-auto-var-init=pattern -fno-omit-frame-pointer -fstack-protector-strong -Wall -Wextra -Werror -Wconversion -Wno-sign-conversion -Wdeprecated -Wno-c99-extensions -Wno-gnu-imaginary-constant -Wno-pedantic -Wimplicit-fallthrough -Wwrite-strings -Wextra-semi -Wnewline-eof -Wnonportable-system-include-path -Wstrict-prototypes -Wthread-safety -Wglobal-constructors -DLIBC_COPT_PUBLIC_PACKAGING -std=gnu++17 -MD -MT libc/src/math/generic/CMakeFiles/libc.src.math.generic.fmaximumf.dir/fmaximumf.cpp.o -MF libc/src/math/generic/CMakeFiles/libc.src.math.generic.fmaximumf.dir/fmaximumf.cpp.o.d -o libc/src/math/generic/CMakeFiles/libc.src.math.generic.fmaximumf.dir/fmaximumf.cpp.o -c /home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc/src/math/generic/fmaximumf.cpp
In file included from /home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc/src/math/generic/fmaximumf.cpp:10:
/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc/src/__support/FPUtil/BasicOperations.h:71:41: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
template <> LIBC_INLINE constexpr float max(float x, float y) {
                                        ^
/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc/src/__support/FPUtil/BasicOperations.h:72:10: note: subexpression not valid in a constant expression
  return __builtin_fmaxf(x, y);
         ^
/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc/src/__support/FPUtil/BasicOperations.h:75:42: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
template <> LIBC_INLINE constexpr double max(double x, double y) {
                                         ^
/home/libc-buildbot/libc-aarch64-ubuntu/libc-aarch64-ubuntu-fullbuild-dbg/llvm-project/libc/src/__support/FPUtil/BasicOperations.h:76:10: note: subexpression not valid in a constant expression
  return __builtin_fmax(x, y);
         ^
2 errors generated.
[88/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.fmaximum_num.__NO_MISC_MATH_BASIC_OPS_OPT.dir/fmaximum_num.cpp.o
[89/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.nextafterbf16.dir/nextafterbf16.cpp.o
[90/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.frexpbf16.dir/frexpbf16.cpp.o
[91/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.lrintbf16.__internal__.dir/lrintbf16.cpp.o
[92/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.nextafterbf16.__internal__.dir/nextafterbf16.cpp.o
[93/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.fdiml.dir/fdiml.cpp.o
[94/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.fsub.__internal__.dir/fsub.cpp.o
[95/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.getpayloadl.__internal__.dir/getpayloadl.cpp.o
[96/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.nearbyintbf16.dir/nearbyintbf16.cpp.o
[97/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.fmaxf.__NO_MISC_MATH_BASIC_OPS_OPT.__internal__.dir/fmaxf.cpp.o
[98/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.truncbf16.__NO_ROUND_OPT.dir/truncbf16.cpp.o
[99/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.nearbyintbf16.__internal__.dir/nearbyintbf16.cpp.o
[100/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.fminimumbf16.__NO_MISC_MATH_BASIC_OPS_OPT.__internal__.dir/fminimumbf16.cpp.o
[101/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.setpayloadbf16.dir/setpayloadbf16.cpp.o
[102/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.getpayloadbf16.__internal__.dir/getpayloadbf16.cpp.o
[103/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.llrintbf16.dir/llrintbf16.cpp.o
[104/1824] Building CXX object libc/src/math/generic/CMakeFiles/libc.src.math.generic.lrintbf16.dir/lrintbf16.cpp.o
ninja: build stopped: subcommand failed.
['ninja', 'libc-unit-tests'] exited with return code 1.
The build step threw an exception...
Traceback (most recent call last):
  File "../llvm-zorg/zorg/buildbot/builders/annotated/libc-linux.py", line 181, in step
    yield

```

</details>

https://github.com/llvm/llvm-project/pull/182169