Fix jit crash on aarch64, mips

The jit testsuite was showing numerous segfaults and fatal
errors for trunk on aarch64; typically on the 2nd iteration of each
test, with errors like:
 test-volatile.c.exe: fatal error: pass ‘rnreg’ not found but is referenced by new pass ‘whole-program’
where the new pass' name varies, and can be bogus, e.g.:
 test-nested-loops.c.exe: fatal error: pass 'rnreg' not found but is referenced by new pass '/tmp/libgccjit-FMb7g3/fake.c'

This is a regression relative to gcc 5.

The root cause is that aarch64_register_fma_steering builds and
registers an "fma_steering" pass after "rnreg", but the
  struct register_pass_info
containing the arguments to register_pass is marked "static".
Hence after the 1st iteration, the pointer to the pass isn't touched,
and we have a use-after-free of the 1st iteration's pass_fma_steering.

The attached patch removes the "static" from the relevant local, so
that the pass pointer is updated before each call to register_pass.

With this patch, the jit testsuite runs successfully (8514 passes) on
gcc113 (aarch64-unknown-linux-gnu).

I used grep to see if there were any other
  "static struct register_pass_info"
in the code, and there's one in the mips backend, so I did the same
change there (untested).

Bootstrap on aarch64 in progress; I don't have mips handy.

OK for trunk if it passes?

gcc/ChangeLog:
	* config/aarch64/cortex-a57-fma-steering.c
	(aarch64_register_fma_steering): Remove "static" from arguments
	to register_pass.
	* config/mips/frame-header-opt.c (mips_register_frame_header_opt):
	Likewise.
---
 gcc/config/aarch64/cortex-a57-fma-steering.c | 2 +-
 gcc/config/mips/frame-header-opt.c           | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

On Thu, Feb 04, 2016 at 10:31:27AM -0500, David Malcolm wrote:
> The jit testsuite was showing numerous segfaults and fatal
> errors for trunk on aarch64; typically on the 2nd iteration of each
> test, with errors like:
>  test-volatile.c.exe: fatal error: pass ‘rnreg’ not found but is referenced by new pass ‘whole-program’
> where the new pass' name varies, and can be bogus, e.g.:
>  test-nested-loops.c.exe: fatal error: pass 'rnreg' not found but is referenced by new pass '/tmp/libgccjit-FMb7g3/fake.c'
> 
> This is a regression relative to gcc 5.
> 
> The root cause is that aarch64_register_fma_steering builds and
> registers an "fma_steering" pass after "rnreg", but the
>   struct register_pass_info
> containing the arguments to register_pass is marked "static".
> Hence after the 1st iteration, the pointer to the pass isn't touched,
> and we have a use-after-free of the 1st iteration's pass_fma_steering.
> 
> The attached patch removes the "static" from the relevant local, so
> that the pass pointer is updated before each call to register_pass.
> 
> With this patch, the jit testsuite runs successfully (8514 passes) on
> gcc113 (aarch64-unknown-linux-gnu).
> 
> I used grep to see if there were any other
>   "static struct register_pass_info"
> in the code, and there's one in the mips backend, so I did the same
> change there (untested).
> 
> Bootstrap on aarch64 in progress; I don't have mips handy.
> 
> OK for trunk if it passes?

The AArch64 part is OK (assuming bootstrap and test succeed), thanks.

James

> 
> gcc/ChangeLog:
> 	* config/aarch64/cortex-a57-fma-steering.c
> 	(aarch64_register_fma_steering): Remove "static" from arguments
> 	to register_pass.
> 	* config/mips/frame-header-opt.c (mips_register_frame_header_opt):
> 	Likewise.
> ---
>  gcc/config/aarch64/cortex-a57-fma-steering.c | 2 +-
>  gcc/config/mips/frame-header-opt.c           | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>