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threadx/scripts
Frédéric Desbiens f3ab36dacc Made the example builds work with LLVM, and fixed four that were broken on Linux (#594)
* Made the example builds work with LLVM, and fixed four that were broken on Linux

The gnu example builds are the natural LLVM path: Arm Toolchain for Embedded is
LLVM based, consumes GNU ld linker scripts, and needs none of the scatter files
or Arm DS projects the ac6 examples carry. So rather than port the ac6 examples,
teach the gnu scripts to drive either toolchain.

Each script now selects the toolchain from a TOOLCHAIN variable that defaults to
gnu, so every existing invocation behaves exactly as before. TOOLCHAIN=atfe
switches the compiler, adds the target triple, passes the entry symbol through
to the linker rather than to the driver, and links the toolchain's own
semihosting library in place of --specs=nosys.specs, which is a GCC spec file
mechanism with no LLVM equivalent. That last choice avoids adding a syscall stub
source to every example.

The scripts are parameterised rather than duplicated. Copies of build scripts
would drift the first time one side was edited, which is the failure this
repository has just spent several changes recovering from.

Four sample scripts could not run on a case-sensitive filesystem at all. They
compiled MP_PrivateTimer.s and V7.s while the files on disk are
MP_PrivateTimer.S and v7.s, and the Cortex-A5 and A9 scripts named MP_GIC.s
where the file is MP_GIC.S. The link lines named V7.o accordingly. Corrected to
match the files, which is why the Cortex-A5, A7, A8 and A9 examples now build on
Linux where before they could not.

Extend scripts/check_clang.sh to link the example builds as well as compile the
sources, since compiling proves the sources parse while only linking exercises
entry symbols, linker scripts and the C library together.

Eight examples are listed as not expected to link, each with its reason, so the
gaps stay visible rather than being silently skipped. Five of them fail with the
GNU toolchain too and are therefore not LLVM problems: the Cortex-M0 example's
crt0 references __text_load_start__, __text_start__ and __text_end__, which its
linker script never defines, while the Cortex-M4 script defines the equivalents;
the arm9, arm11, Cortex-R4 and Cortex-R5 examples need newlib multilib variants
that are not present in every GNU toolchain packaging. The Cortex-A12, A15 and
A17 examples fail only with LLVM, because their link line omits -nostartfiles so
the toolchain's own crt0 is linked and wants picolibc's __data_start,
__data_source, __data_size and __bss_size, which their linker script does not
define.

Verified by building every example with both toolchains. Seven link with both:
Cortex-A5, A7, A8, A9, M3, M4 and M7. The GNU results are unchanged where they
worked before, and now also succeed for the four scripts with the case bug.

Assisted-by: Claude Code (Opus 5) <noreply@anthropic.com>

* Resolved the compiler path before running the example builds

The example stage runs each build script from inside its own directory, so a
relative path passed with --clang stopped resolving there and every example
build failed instantly. Local runs passed an absolute path and did not show it;
the CI job passes a path relative to the workspace root, which did.

Resolve the compiler to an absolute path once, before any directory change, and
print it so the toolchain in use is visible in the log.

Assisted-by: Claude Code (Opus 5) <noreply@anthropic.com>

* Parameterised the archiver as well, and stopped the check hiding failures

The toolchain selection covered the compiler but not arm-none-eabi-ar, which the
scripts invoke 628 times to assemble the library archive. A machine with an LLVM
toolchain and no GNU one therefore could not build any example, which is exactly
the situation in CI: the runner has no Arm GNU toolchain installed. Local runs
had one, so this only appeared once the job ran.

Select the archiver alongside the compiler, taking llvm-ar from beside clang in
the toolchain. The four scripts that call arm-none-eabi-ld directly are left
alone: they are arm9, arm11, Cortex-R4 and Cortex-R5, all already listed as not
expected to link, and their invocations are specific to GNU ld in ways that
parameterising would not resolve.

The check reported "example build produced no image" and then filtered the log
for lines containing "error", which hid the actual cause, since a missing tool
reports "command not found" or "No such file or directory". It now prints the
tail of the log. That filtering cost two CI round trips to diagnose something
the first run already knew.

Verified by shadowing arm-none-eabi-gcc, arm-none-eabi-ar, arm-none-eabi-ld and
the aarch64 equivalents with stubs that fail loudly, then running the whole
check: all 711 sources assemble, all eight profiles compile and all seven
example builds link without any GNU tool being invoked. The GNU default path
still produces an identical image. The diagnostics were confirmed by pointing
the archiver at a name that does not exist and checking that the reason appears.

Assisted-by: Claude Code (Opus 5) <noreply@anthropic.com>
2026-08-10 15:10:34 -04:00
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