[rascani]

Summary

The Cortex-M size tests should measure ExecuTorch's contribution to binary size. The POSIX platform layer and, for GNU, the full C/C++ libraries with exception support and demangling obscure that contribution. Select minimal PAL for both existing configurations and nano.specs for the GNU build to reduce this overhead and make the tests more sensitive to changes in ExecuTorch.

Initialize C and C++ flags with nano.specs so it applies during compilation and linking while preserving the build script's existing flags. Set the runtime size limits to 34,000 bytes for GNU and 57,000 bytes for Zephyr. The GNU configuration uses nano's abort-on-allocation-failure behavior.

Test plan

Built both size targets on base 0549e1ee61 using Cortex-M55, C++17, Release with size optimization and logging disabled; GNU Arm 15.2.Rel1 and Zephyr SDK 1.0.1 (GCC 14.3.0). Stripped ELF file sizes in bytes:

Configuration	Binary	Before	After	Saved
GNU bare-metal	size_test	117,348	33,372	83,976
GNU bare-metal	size_test_all_ops	1,245,820	1,156,180	89,640
Zephyr	size_test	56,332	55,800	532
Zephyr	size_test_all_ops	1,155,048	1,154,512	536

All 263 C/C++ compile commands and both size-test compile/link commands select nano.specs while retaining the existing compiler flags. Both GNU binaries retain FileDataLoader and contain no exception-unwinder or demangler symbols. Workflow YAML parsing, shell syntax, and both size limits pass.

Authored with AI assistance using Codex.

[rascani]

Stack from ghstack (oldest at bottom):

• Build operator lookup names without snprintf #24217
• -> Use minimal PAL and nano libraries in Cortex-M size tests #24216

[pytorch-bot]

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As of commit 038aacb with merge base 0549e1e ():
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