[PATCH] MSP430: Fix CFA generation during function epilogues

[Jeff Law]

On 9/9/20 4:33 AM, Jozef Lawrynowicz wrote:
> There is no CFA information generated for instructions which manipulate the
> stack during function epilogues. This means a debugger cannot determine the
> position of variables on the stack whilst the epilogue is in progress.
>
> This can cause the debugger to give erroneous information when printing a
> backtrace whilst stepping through the epilogue, or cause software watchpoints
> set on stack variables to become invalidated after a function epilogue
> is executed.
>
> The patch fixes this by marking stack manipulation insns as
> frame_related, and adding reg_note RTXs to stack pop instructions in the
> epilogue.
>
> Successfully regtested on trunk for msp430-elf in the default, -mlarge,
> -mcpu=msp430 and -mlarge/-mcode-region=either/-mdata-region=either
> configurations.
>
> This fixes some tests from watchpoint.exp in the GDB testsuite.
>
> Ok for trunk?
>
> Thanks,
> Jozef
>
> 0001-MSP430-Fix-CFA-generation-during-function-epilogues.patch
>
> From 272b38a374eddf7327a61ff9b1730f0a2dd40233 Mon Sep 17 00:00:00 2001
> From: Jozef Lawrynowicz <jozef.l@mittosystems.com>
> Date: Mon, 7 Sep 2020 20:34:40 +0100
> Subject: [PATCH] MSP430: Fix CFA generation during function epilogues
>
> There is no CFA information generated for instructions which manipulate the
> stack during function epilogues. This means a debugger cannot determine the
> position of variables on the stack whilst the epilogue is in progress.
>
> This can cause the debugger to give erroneous information when printing a
> backtrace whilst stepping through the epilogue, or cause software watchpoints
> set on stack variables to become invalidated after a function epilogue
> is executed.
>
> The patch fixes this by marking stack manipulation insns as
> frame_related, and adding reg_note RTXs to stack pop instructions in the
> epilogue.
>
> gcc/ChangeLog:
>
> 	* config/msp430/msp430.c (increment_stack): Mark insns which increment
> 	the stack as frame_related.
> 	(msp430_expand_prologue): Add comments.
> 	(msp430_expand_epilogue): Mark insns which decrement
> 	the stack as frame_related.
> 	Add reg_note to stack pop insns describing position of register
> 	variables on the stack.

OK

jeff


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