[FMV][AArch64] Fix missing FMV defines for AArch64 in LNT Makefile

[IamYJLee]

Add conditional CFLAGS definitions for AArch64 targets to support FMV-related behavior on Darwin and Linux platforms.

• Adds -DHAS_DARWIN_FMV when ARCH=AArch64 and TARGET_OS=Darwin
• Adds -DHAS_LINUX_FMV when ARCH=AArch64 and TARGET_OS=Linux

This change fixes build errors when running LNT tests on AArch64 systems with platform-specific FMV handling.

This patch reflects the changes from llvm/llvm-test-suite@d24d5dcd.

ERROR CONTEXT

Before this patch, LNT test runs on AArch64 platforms (e.g., macOS arm64) could fail with missing symbol errors:

--- Tested: 140 tests --
FAIL: SingleSource/Benchmarks/Misc/aarch64-init-cpu-features.compile_time (1 of 140)
FAIL: SingleSource/Benchmarks/Misc/aarch64-init-cpu-features.execution_time (29 of 140)
Processing Times

Undefined symbols for architecture arm64:
  "_RUNTIME_INIT", referenced from:
      _main in aarch64-init-cpu-features.llvm.o
      _main in aarch64-init-cpu-features.llvm.o
      _main in aarch64-init-cpu-features.llvm.o
ld: symbol(s) not found for architecture arm64

[labrinea]

I am a bit puzzled with the equivalent cmake code

file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/CheckHasAArch64FMV.h "void __init_cpu_features_resolver(void);")
check_symbol_exists(__init_cpu_features_resolver ${CMAKE_CURRENT_BINARY_DIR}/CheckHasAArch64FMV.h HAS_AARCH64_FMV)

The way I read it HAS_AARCH64_FMV is always true? Am I mistaken, do we need it here too perhaps? cc @jroelofs

[IamYJLee]

@labrinea Thank you for your comment.

I've confirmed how check_symbol_exists functions and understand that HAS_AARCH64_FMV is not always true. In my environment, when I configure the project using CMakeLists.txt, HAS_AARCH64_FMV is set to False.

However, when I run LNT with a Makefile that includes my modifications, the build and execution complete without any issues.

In other words, even though check_symbol_exists confirms that the __init_cpu_features_resolver symbol is missing, there are no problems compiling and running aarch64-init-cpu-features.c.

[IamYJLee]

@labrinea
I'm using the following command and encountering an Undefined Symbol error.

./mysandbox/bin/lnt runtest nt --sandbox ./result --cc ./llvm-project/build/bin/clang --test-suite ./llvm-test-suite -j 16 --only-test SingleSource/Benchmarks/Misc --isysroot `xcrun --show-sdk-path`

To match the CMakeLists.txt configuration and resolve this, I've made the following changes:

1. I added an #if defined() directive to aarch64-init-cpu-features.c to prevent the problematic code from being compiled when HAS_***_FW is False. (My initial attempt to use PROGRAM_TO_SKIP to exclude the file did not work.)

2. To replicate the logic from the CMakeLists.txt (below code), I added a step that generates and compiles a temporary header file. The result of this check is stored in the CHECK_FMV variable.
   

   llvm-test-suite/SingleSource/Benchmarks/Misc/CMakeLists.txt

   Lines 39 to 40 in 299a0b3

   	file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/CheckHasAArch64FMV.h "void __init_cpu_features_resolver(void);")
   	check_symbol_exists(__init_cpu_features_resolver ${CMAKE_CURRENT_BINARY_DIR}/CheckHasAArch64FMV.h HAS_AARCH64_FMV)

Testing

In my local environment, the check for the __init_cpu_features* symbol always results in 'no'. I've confirmed my changes work as intended by manually setting the CHECK_FMV variable to both 'yes' and 'no'.

Could you please test these changes in an environment where the __init_cpu_features* symbol check would result in 'yes'?