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git_commit commit b3a199469c9d54fb3bdabf6dff5677b401f8fef6
Author: Louis Dionne <ldionne.2@gmail.com>
Date: Thu Oct 16 23:40:58 2025 -0400

[libc++] Properly implement array cookies in the ARM ABI (#160182)

When we implemented array cookie support for hardening std::unique_ptr,
the implementation was only done for the Itanium ABI. I did not
initially realize that ARM was using a different ABI for array cookies,
so unique_ptr should not have been hardened on ARM.

However, we were also incorrectly setting the ABI-detection macro: we
were pretending to be using a vanilla Itanium ABI when in reality the
(similar but different) ARM ABI was in use. As a result, unique_ptr was
using the wrong representation for array cookies on ARM, which
fortunately only mattered in the case of overaligned types.

This patch fixes that.

rdar://160852193
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ldionne-old-macbook-results test results

Run Order Start Time Duration
Current 556303 2025-12-16T16:40:01 0:00:00
Previous 556296 2025-12-16T16:40:01 0:00:00
Baseline 485288 2025-12-16T16:40:01 0:00:00


Tests Summary

Status Group # # (B)
Performance Regressions 2 0
Performance Improvements 2 0
Added Tests 0 16
Unchanged Tests 76 64
Total Tests 80

Performance Regressions - execution_time Δ Previous Current σ Δ (B) σ (B)
710_omnetpp_r 4.42% 8.310 8.678 - 0.00% -
727_cppcheck_r 1.60% 24.456 24.846 - 0.00% -

Performance Improvements - execution_time Δ Previous Current σ Δ (B) σ (B)
753_ns3_r -1.93% 10.297 10.098 - 0.00% -
766_femflow_r -1.59% 12.971 12.765 - 0.00% -

Added Tests - execution_time
706_stockfish_r
707_ntest_r
709_cactus_r
710_omnetpp_r
721_gcc_r
723_llvm_r
727_cppcheck_r
729_abc_r
731_astcenc_r
735_gem5_r
736_ocio_r
737_gmsh_r
748_flightdm_r
750_sealcrypto_r
753_ns3_r
766_femflow_r


Report Time: 0.06s
Name Current %
706_stockfish_r 20.652 -
707_ntest_r 16.227 -
709_cactus_r 19.276 -
710_omnetpp_r 8.678 4.42%
721_gcc_r 12.921 -
723_llvm_r 11.469 -
727_cppcheck_r 24.846 1.60%
729_abc_r 18.829 -
731_astcenc_r 10.115 -
735_gem5_r 13.321 -
736_ocio_r 16.160 -
737_gmsh_r 12.843 -
748_flightdm_r 8.813 -
750_sealcrypto_r 18.490 -
753_ns3_r 10.098 -1.93%
766_femflow_r 12.765 -1.59%
Geometric Mean 14.041 -