| commit | e1e1836bbd70e4f30bd0be97b9d81eabfd6b45c8 | [log] [tgz] |
|---|---|---|
| author | Omair Javaid <omair.javaid@linaro.org> | Thu Jun 12 19:38:42 2025 +0500 |
| committer | GitHub <noreply@github.com> | Thu Jun 12 19:38:42 2025 +0500 |
| tree | 161853a2d8cb724fdc46c3fabac05f2c4c2201df | |
| parent | cc17f68e566ab7db4ac8e95dc857e49e10d8366c [diff] |
[CodeGen] Inline stack guard check on Windows (#136290) This patch optimizes the Windows security cookie check mechanism by moving the comparison inline and only calling __security_check_cookie when the check fails. This reduces the overhead of making a DLL call for every function return. Previously, we implemented this optimization through a machine pass (X86WinFixupBufferSecurityCheckPass) in PR #95904 submitted by @mahesh-attarde. We have reverted that pass in favor of this new approach. Also we have abandoned the AArch64 specific implementation of same pass in PR #121938 in favor of this more general solution. The old machine instruction pass approach: - Scanned the generated code to find __security_check_cookie calls - Modified these calls by splitting basic blocks - Added comparison logic and conditional branching - Required complex block management and live register computation The new approach: - Implements the same optimization during instruction selection - Directly emits the comparison and conditional branching - No need for post-processing or basic block manipulation - Disables optimization at -Oz. Thanks @tamaspetz, @efriedma-quic and @arsenm for their help.
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