https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104596
Bug ID: 104596
Summary: Means to add a comment in the assembly
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: vries at gcc dot gnu.org
Target Milestone: ---
I wanted to mark some insns in a way that is visible in the assembly, without
having to tinker with the .md file.
The user-level equivalent would be something like:
...
asm ("// Start: added by x")
...
asm ("// End: added by x")
...
So I wrote:
...
static rtx
gen_comment (const char *s)
{
const char *sep = " ";
size_t len = strlen (ASM_COMMENT_START) + strlen (sep) + strlen (s) + 1;
char *comment = (char *) alloca (len);
snprintf (comment, len, "%s%s%s", ASM_COMMENT_START, sep, s);
return gen_rtx_ASM_INPUT_loc (VOIDmode, ggc_strdup (comment),
cfun->function_start_locus);
}
...
and used it to generate comments like this:
...
// #APP
// 2 "pr53465.c" 1
// Start: Added by -minit-regs=3:
// #NO_APP
mov.u32 %r25, 0;
// #APP
// 2 "pr53465.c" 1
// End: Added by -minit-regs=3:
// #NO_APP
...
This however is a bit verbose.
The APP/NO_APP is there to separate user insn from compiler insn, but in this
case, the compiler added the comments.
Furthermore, the file info is not meaningful either, we just use
cfun->function_start_locus because with UNKNOWN_LOCATION we run into a
segfault.
Both these issues are addressed by:
...
diff --git a/gcc/final.cc b/gcc/final.cc
index a9868861bd2c..5d47f3d5ba0e 100644
--- a/gcc/final.cc
+++ b/gcc/final.cc
@@ -2642,15 +2642,20 @@ final_scan_insn_1 (rtx_insn *insn, FILE *file, int
optimize_p
ATTRIBUTE_UNUSED,
if (string[0])
{
expanded_location loc;
-
- app_enable ();
- loc = expand_location (ASM_INPUT_SOURCE_LOCATION (body));
- if (*loc.file && loc.line)
- fprintf (asm_out_file, "%s %i \"%s\" 1\n",
- ASM_COMMENT_START, loc.line, loc.file);
+ bool unknown_loc_p
+ = ASM_INPUT_SOURCE_LOCATION (body) == UNKNOWN_LOCATION;
+
+ if (!unknown_loc_p)
+ {
+ app_enable ();
+ loc = expand_location (ASM_INPUT_SOURCE_LOCATION (body));
+ if (*loc.file && loc.line)
+ fprintf (asm_out_file, "%s %i \"%s\" 1\n",
+ ASM_COMMENT_START, loc.line, loc.file);
+ }
fprintf (asm_out_file, "\t%s\n", string);
#if HAVE_AS_LINE_ZERO
- if (*loc.file && loc.line)
+ if (!unknown_loc_p && loc.file && *loc.file && loc.line)
fprintf (asm_out_file, "%s 0 \"\" 2\n", ASM_COMMENT_START);
#endif
}
...
after which we can do in gen_comment:
...
- return gen_rtx_ASM_INPUT_loc (VOIDmode, ggc_strdup (comment),
- cfun->function_start_locus);
+ return gen_rtx_ASM_INPUT (VOIDmode, ggc_strdup (comment));
...
and have the less verbose:
...
// Start: Added by -minit-regs=3:
mov.u32 %r25, 0;
// End: Added by -minit-regs=3:
...
