llvm-project

0c9f909b - [AArch64][SME] Fix restoring callee-saves from FP with hazard padding (#143371)

[AArch64][SME] Fix restoring callee-saves from FP with hazard padding (#143371) Currently, when hazard-padding is enabled a (fixed-size) hazard slot is placed in the CS area, just after the frame record. The size of this slot is part of the "CalleeSaveBaseToFrameRecordOffset". The SVE epilogue emission code assumed this offset was always zero, and incorrectly setting the stack pointer, resulting in all SVE registers being reloaded from incorrect offsets. ``` | prev_lr | | prev_fp | | (a.k.a. "frame record") | |-----------------------------------| <- fp(=x29) | <hazard padding> | |-----------------------------------| <- callee-saved base | | | callee-saved fp/simd/SVE regs | | | |-----------------------------------| <- SVE callee-save base ``` i.e. in the above diagram, the code assumed `fp == callee-saved base`.