cortex-m-rt: Remove LR push, to ensure the stack is 8-byte aligned. #467
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jamesmunns
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Feb 13, 2023
jamesmunns
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Feb 13, 2023
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This was causing incorrect execution of code optimized with the assumption the stack is 8-byte aligned.
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adamgreig
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On balance I want to go this route, instead of #463. Thanks for preparing all the PRs @Dirbaio, and thanks to everyone else who helped investigate, especially @Dirbaio and @jamesmunns, and @peter9477 for spotting the issue in the first place.
There's a lot of useful context, explanation, and research in the #463 thread, though, so future readers should check it out.
Apologies in advance to the probe-run team; I think in the end it's best to go directly to the solution we want to stick with, and hopefully it's not too bad to patch up probe-run to eliminate the warning it will start emitting.
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470: Prepare for cortex-m-rt v0.7.3 r=thalesfragoso a=adamgreig This fixes the miscompilation in #467, so I'd like to release it as soon as possible. Co-authored-by: Adam Greig <[email protected]>
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This was causing incorrect execution of code optimized with the assumption the stack is 8-byte aligned.
Alternate version of #463
bl mainanyway.Remove the .cfi directives, since Reset now has no correct CFI info. I think this is the "correct" thing to do here.Initialize the frame pointer in R7 (suggestion from @jamesmunns)