Re: [PATCH 1/2] gcc/file-prefix-map: Allow remapping of relative paths

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Fri, 2022-11-04 at 10:12 +0100, Eric Botcazou wrote:
> > gcc/ChangeLog:
> > 
> >     * file-prefix-map.cc (remap_filename): Allow remapping of
> > relative paths
> 
> Small regression in Ada though, probably a missing guard somewhere:
> 
>                 === gnat tests ===
> 
> 
> Running target unix
> FAIL: gnat.dg/specs/coverage1.ads (test for excess errors)
> 
> In order to reproduce, configure the compiler with Ada enabled, build
> it, and 
> copy $[srcdir)/gcc/testsuite/gnat.dg/specs/coverage1.ads into the
> build 
> directory, then just issue:
> 
> gcc/gnat1 -quiet coverage1.ads -ftest-coverage -Igcc/ada/rts
> 
> raised STORAGE_ERROR : stack overflow or erroneous memory access

It took me a while to work out how to get ada to build. When I did I
found it was faulting due to a NULL filename being passed to lbasename:

Program received signal SIGSEGV, Segmentation fault.
lbasename (name=0x0) at gcc/libiberty/lbasename.c:82
82	  return unix_lbasename (name);
(gdb) bt
#0  lbasename (name=0x0) at gcc/libiberty/lbasename.c:82
#1  0x0000000000f3d566 in remap_filename (maps=0x0, filename=filename@entry=0x0) at gcc/gcc/file-prefix-map.cc:76
#2  0x0000000000f3d6df in remap_profile_filename (filename=filename@entry=0x0) at gcc/gcc/file-prefix-map.cc:158
#3  0x0000000000e59f59 in coverage_begin_function (lineno_checksum=lineno_checksum@entry=595732889, cfg_checksum=cfg_checksum@entry=2754642872)
    at gcc/gcc/coverage.cc:650
#4  0x00000000012263c0 in branch_prob (thunk=thunk@entry=false) at gcc/gcc/profile.cc:1400
#5  0x00000000013b1205 in tree_profiling () at gcc/gcc/tree-profile.cc:782
#6  (anonymous namespace)::pass_ipa_tree_profile::execute (this=<optimised out>) at gcc/gcc/tree-profile.cc:888
#7  0x00000000011ef30b in execute_one_pass (pass=0x36ebea0) at gcc/gcc/passes.cc:2644
#8  0x00000000011f0697 in execute_ipa_pass_list (pass=0x36ebea0) at gcc/gcc/passes.cc:3093
#9  0x0000000000e4c28d in ipa_passes () at gcc/gcc/cgraphunit.cc:2170
#10 symbol_table::compile (this=0x7ffff718f000) at gcc/gcc/cgraphunit.cc:2291
#11 0x0000000000e4ec08 in symbol_table::compile (this=0x7ffff718f000) at gcc/gcc/cgraphunit.cc:2271
#12 symbol_table::finalize_compilation_unit (this=0x7ffff718f000) at gcc/gcc/cgraphunit.cc:2543
#13 0x00000000012cfea0 in compile_file () at gcc/gcc/toplev.cc:471
#14 0x00000000009a727c in do_compile (no_backend=false) at gcc/gcc/toplev.cc:2125
#15 toplev::main (this=this@entry=0x7fffffffe21e, argc=<optimised out>, argc@entry=4, argv=<optimised out>, argv@entry=0x7fffffffe348) at gcc/gcc/toplev.cc:2277
#16 0x00000000009a8a8b in main (argc=4, argv=0x7fffffffe348) at gcc/gcc/main.cc:39

I can send the obvious patch to make it work as before and ignore the
NULL which fixes this. I'm not sure if it should really be passing NULL
around in the first place or not which is why I'm sharing the
backtrace.

Cheers,

Richard