[PATCH][AARCH64] PR target/84521 Fix frame pointer corruption with -fomit-frame-pointer with __builtin_setjmp

[Sudakshina Das]

Hi Eric

On 07/06/18 16:33, Eric Botcazou wrote:
>> Sorry this fell off my radar. I have reg-tested it on x86 and tried it
>> on the sparc machine from the gcc farm but I think I couldn't finished
>> the run and now its showing to he unreachable.
> 
> The patch is a no-op for SPARC because it defines the nonlocal_goto pattern.
> 
> But I would nevertheless strongly suggest _not_ fiddling with the generic code
> like that and just defining the nonlocal_goto pattern for Aarch64 instead.
> 

Thank you for the suggestion, I have edited the patch accordingly and
defined the nonlocal_goto pattern for AArch64. This has also helped take
care of the issue with __builtin_longjmp that Wilco had mentioned in his
comment on the PR (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84521#c19).

I have also modified the test case according to Wilco's comment to add 
an extra jump buffer. This test case passes with AArch64 but fails on
x86 trunk as follows (It may fail on other targets as well):

FAIL: gcc.c-torture/execute/pr84521.c   -O1  execution test
FAIL: gcc.c-torture/execute/pr84521.c   -O2  execution test
FAIL: gcc.c-torture/execute/pr84521.c   -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions  execution test
FAIL: gcc.c-torture/execute/pr84521.c   -O3 -g  execution test
FAIL: gcc.c-torture/execute/pr84521.c   -Os  execution test
FAIL: gcc.c-torture/execute/pr84521.c   -O2 -flto -fno-use-linker-plugin
-flto-partition=none  execution test
FAIL: gcc.c-torture/execute/pr84521.c   -O2 -flto -fuse-linker-plugin
-fno-fat-lto-objects  execution test

Testing: Bootstrapped and regtested on aarch64-none-linux-gnu.

Is this ok for trunk?

Sudi

*** gcc/ChangeLog ***

2018-06-14  Sudakshina Das  <sudi.das@arm.com>

	PR target/84521
	* config/aarch64/aarch64.h (DONT_USE_BUILTIN_SETJMP): Update comment.
	* config/aarch64/aarch64.c (aarch64_needs_frame_chain): Add
	cfun->has_nonlocal_label to force frame chain.
	(aarch64_builtin_setjmp_frame_value): New.
	(TARGET_BUILTIN_SETJMP_FRAME_VALUE): Define.
	* config/aarch64/aarch64.md (nonlocal_goto): New.

*** gcc/testsuite/ChangeLog ***

2018-06-14  Sudakshina Das  <sudi.das@arm.com>

	PR target/84521
	* gcc.c-torture/execute/pr84521.c: New test.
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