[ was: Re: [PATCH, 0/4] Handle 
GOMP_OPENACC_NVPTX_{DISASM,SAVE_TEMPS,JIT} in libgomp nvptx plugin ]

On 06/26/2017 01:24 PM, Tom de Vries wrote:
> Hi,
> 
> I've written a patch series to facilitate debugging libgomp openacc 
> testcase failures on the nvptx accelerator.
> 
> 
> When running an openacc test-case on an nvptx accelerator, the following 
> happens:
> - the plugin obtains the ptx assembly for the acceleration kernels
> - it calls the cuda jit to compile and link the ptx into a module
> - it loads the module
> - it starts an acceleration kernel

A typical scenario when developing the compiler is:
- run gcc test.c -save-temps
- run a.out
- edit test.s to fix bug or make code faster or smaller
- run gcc test.s
- run a.out
- edit compiler sources to make the compiler do the same as the .s edit

With openacc test-cases, this scenario is currently not available for 
ptx assembly. Using -save-temps -foffload=-save-temps we can get a .s 
containing ptx. But to insert the edited .s back into the compilation 
flow is difficult.

This patch facilitates such a scenario in the nvptx plugin.
- we define GOMP_OPENACC_NVPTX_PTXRW == 'w', and the plugin writes the
   ptx assembly into a series of files
- we edit one of those files
- we define GOMP_OPENACC_NVPTX_PTXRW == 'r', and the plugin reads the
   ptx assembly back from those files, and uses that instead of the ptx
   in the executable.

I've tested this patch series on top of gomp-4_0-branch, by running an
openacc testcase from the command line and going through the 
write-edit-readscenario with an observable ptx edit.

OK for trunk if bootstrap and reg-test on x86_64 with nvidia accelerator
succeeds?

Thanks,
- Tom