https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63837
--- Comment #7 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
(In reply to Manuel López-Ibáñez from comment #6)
> Thanks for the testcase. It seems that the GCC_COMPARE_DEBUG=0 uses a
> temporary file
>
> ./cc1 -quiet -iprefix
> /home/manuel/test1/217394M/build/gcc/../lib/gcc/x86_64-unknown-linux-gnu/5.0.
> 0/ -isystem ./include -isystem ./include-fixed /dev/null -quiet -dumpbase
> null "-mtune=generic" "-march=x86-64" -auxbase null -Wpointer-sign
> "-fcompare-debug=-gtoggle" "-frandom-seed=0x6daada6b94b95048"
> "-fdump-final-insns=/tmp/cc3xSGvK.gkd" -o /tmp/cc3L00jg.s
>
> but the GCC_COMPARE_DEBUG=1 uses /dev/null:
>
> ./cc1 -quiet -iprefix
> /home/manuel/test1/217394M/build/gcc/../lib/gcc/x86_64-unknown-linux-gnu/5.0.
> 0/ -isystem ./include -isystem ./include-fixed /dev/null -quiet -dumpbase
> null.gk "-mtune=generic" "-march=x86-64" -auxbase null -gtoggle
> -Wpointer-sign -w "-fcompare-debug=-gtoggle" -fcompare-debug-second -o
> /dev/null "-frandom-seed=0x6daada6b94b95048"
> "-fdump-final-insns=/tmp/ccMDEp8L.gk.gkd"
>
> which triggers the heuristic. I can simply ignore /dev/null when checking
> for input==output. I'm testing this patch:
>
> Index: gcc.c
> ===================================================================
> --- gcc.c (revision 217457)
> +++ gcc.c (working copy)
> @@ -4047,11 +4047,12 @@ process_command (unsigned int decoded_op
> read_cmdline_option (&global_options, &global_options_set,
> decoded_options + j, UNKNOWN_LOCATION,
> CL_DRIVER, &handlers, global_dc);
> }
>
> - if (output_file && strcmp (output_file, "-"))
> + if (output_file && strcmp (output_file, "-")
> + && strcmp (output_file, HOST_BIT_BUCKET))
> {
> int i;
> for (i = 0; i < n_infiles; i++)
> if ((!infiles[i].language || infiles[i].language[0] != '*')
> && canonical_filename_eq (infiles[i].name, output_file))
> Index: toplev.c
> ===================================================================
> --- toplev.c (revision 217457)
> +++ toplev.c (working copy)
> @@ -940,11 +940,12 @@ init_asm_output (const char *name)
> strcat (dumpname, ".s");
> asm_file_name = dumpname;
> }
> if (!strcmp (asm_file_name, "-"))
> asm_out_file = stdout;
> - else if (!canonical_filename_eq (asm_file_name, name))
> + else if (!canonical_filename_eq (asm_file_name, name)
> + || !strcmp (asm_file_name, HOST_BIT_BUCKET))
> asm_out_file = fopen (asm_file_name, "w");
> else
> /* Use fatal_error (UNKOWN_LOCATION) instead of just fatal_error to
> prevent gcc from printing the first line in the current file. */
> fatal_error (UNKNOWN_LOCATION,
>
> If you can test it on your side, it would be helpful.
Your patch fixes the issue. Thank you.
