Udit Jain 6f0da60bd7 libs/libbuiltin/compiler-rt: skip unsupported Arm VFP builtins asm
The compiler-rt builtins build globs every arm/*.S source, but several of
those hand-written assembly files require FPU features the target may not
have.  Upstream compiler-rt selects them conditionally; NuttX did not, so
BUILTIN_COMPILER_RT builds for single-precision-FPU Arm targets (e.g.
Cortex-M33, -mfpu=fpv5-sp-d16) failed to assemble with errors such as
"selected FPU does not support instruction -- vadd.f64".

Filter the source list to match the configured FPU, in both the Makefile
and CMake builds:
  - chkstk.S / chkstk2.S are Windows/MinGW-only stack probes, always dropped;
  - with no hardware FPU (!CONFIG_ARCH_FPU) all arm/*vfp.S are dropped;
  - with a single-precision FPU (!CONFIG_ARCH_DPFPU) the double-precision
    *df*vfp.S routines are dropped.

Reproduced against compiler-rt 17.0.1 with arm-none-eabi-gcc 14.2 using the
Cortex-M33 single-precision flags: 18 of 86 arm/*.S files failed to assemble
(17 double-precision *df*vfp.S plus chkstk.S); after the filter all remaining
68 files assemble cleanly.

Fixes: https://github.com/apache/nuttx/issues/17386
Generated-by: Claude (Anthropic)
Signed-off-by: Udit Jain <uditjainstjis@gmail.com>
2026-07-31 15:37:33 -03:00

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