[ATFE] Configure ATFE to exclude libc-provided AEABI builtins from compiler-rt #326
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
… the ATFE to exclude libc-provided AEABI builtins. We don't want two implementations of the __aeabi runtime in two different libraries. We could suppress the compiler-rt implementation at build time so there's only the picolibc definition. This patch llvm/llvm-project#137952 introduced a new cmake flag called COMPILER_RT_EXCLUDE_LIBC_PROVIDED_ARM_AEABI_BUILTINS to support this functionality. When enabled, this flag excludes the following ARM AEABI memory function implementations from the compiler-rt build: __aeabi_memcmp __aeabi_memset __aeabi_memcpy __aeabi_memmove These functions are already provided by standard C libraries like newlib, and picolibc, so excluding them avoids duplicate symbol definitions and reduces unnecessary code duplication. Also we can now remove the downstream patch that changed the library order to put -lc before compiler-rt builtins as there is now this recent upstream addition of the COMPILER_RT_EXCLUDE_LIBC_PROVIDED_ARM_AEABI_BUILTINS flag.
simpal01
changed the title
simpal01
changed the title
simpal01
added a commit
to simpal01/arm-toolchain
that referenced
this pull request
May 22, 2025
…th llvm-libc. Previously, the following symbols were excluded from the build due to the patch introduced in arm#326 __aeabi_memcmp __aeabi_memset __aeabi_memcpy __aeabi_memmove LLVM libc currently does not provide implementations for __aeabi* symbols. This change ensures that the above implementations from compiler-rt are preserved when linking with llvm-libc , to avoid missing symbol errors at link time.
simpal01
added a commit
that referenced
this pull request
May 22, 2025
…th llvm-libc. (#343) Previously, the following symbols were excluded from the build due to the patch introduced in #326 __aeabi_memcmp __aeabi_memset __aeabi_memcpy __aeabi_memmove LLVM libc currently does not provide implementations for __aeabi* symbols. This change ensures that the above implementations from compiler-rt are preserved when linking with llvm-libc , to avoid missing symbol errors at link time.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
We don't want two implementations of the __aeabi runtime in two different libraries. We could suppress the compiler-rt implementation at build time so there's only the picolibc definition. This patch llvm/llvm-project#137952 introduced a new cmake flag called
COMPILER_RT_EXCLUDE_LIBC_PROVIDED_ARM_AEABI_BUILTINS to support this functionality.
When enabled, this flag excludes the following ARM AEABI memory function implementations from the compiler-rt build:
These functions are already provided by standard C libraries like newlib, and picolibc, so excluding them avoids duplicate symbol definitions and reduces unnecessary code duplication.
Also we can now remove the downstream patch that changed the library order to put -lc before compiler-rt builtins as there is now this recent upstream addition of the
COMPILER_RT_EXCLUDE_LIBC_PROVIDED_ARM_AEABI_BUILTINS flag.