[PATCH] gfortran: Respect target's NO_DOT_IN_LABEL in trans-common.cc

[PATCH] gfortran: Respect target's NO_DOT_IN_LABEL in trans-common.cc

[Roger Sayle]

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This patch fixes 9 unexpected failures in the gfortran testsuite on
nvptx-none.  The issue is that gfortran's EQUIVALENCE internally uses
symbols such as "equiv.0" even on platforms that define NO_DOT_IN_LABEL.
On nvptx-none, this then results in the following error message(s):
ptxas application ptx input, fatal: Parsing error near '.0': syntax error
ptxas fatal   : Ptx assembly aborted due to errors

The fix is to tweak trans-common.cc to respect the target's NO_DOT_IN_LABEL
(and NO_DOLLAR_IN_LABEL) when generating internal equiv.%d symbols.
Only the nvptx, mmix and xtensa backends define NO_DOT_IN_LABEL which
explains why no-one has spotted/fixed this issue since the problematic
code was last changed back in 2005(!).

This patch has been tested on nvptx-none hosted by x86_64-pc-linux-gnu
with make and make -k check with no new failures, and the nine fewer
failures in the gfortran testsuite described above.  Ok for mainline?


2022-02-10  Roger Sayle  <roger@nextmovesoftware.com>

gcc/fortran/ChangeLog
	* trans-common.cc (GFC_EQUIV_FMT): New macro respecting the
	target's NO_DOT_IN_LABEL and NO_DOLLAR_IN_LABEL preferences.
	(build_equiv_decl): Use GFC_EQUIV_FMT here.


Thanks in advance,
Roger
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diff --git a/gcc/fortran/trans-common.cc b/gcc/fortran/trans-common.cc
index 7b4d198..184a976 100644
--- a/gcc/fortran/trans-common.cc
+++ b/gcc/fortran/trans-common.cc
@@ -338,6 +338,13 @@ build_field (segment_info *h, tree union_type, record_layout_info rli)
   h->field = field;
 }
 
+#if !defined (NO_DOT_IN_LABEL)
+#define GFC_EQUIV_FMT "equiv.%d"
+#elif !defined (NO_DOLLAR_IN_LABEL)
+#define GFC_EQUIV_FMT "equiv$%d"
+#else
+#define GFC_EQUIV_FMT "equiv_%d"
+#endif
 
 /* Get storage for local equivalence.  */
 
@@ -356,7 +363,7 @@ build_equiv_decl (tree union_type, bool is_init, bool is_saved, bool is_auto)
       return decl;
     }
 
-  snprintf (name, sizeof (name), "equiv.%d", serial++);
+  snprintf (name, sizeof (name), GFC_EQUIV_FMT, serial++);
   decl = build_decl (input_location,
 		     VAR_DECL, get_identifier (name), union_type);
   DECL_ARTIFICIAL (decl) = 1;

Re: [PATCH] gfortran: Respect target's NO_DOT_IN_LABEL in trans-common.cc

[Tobias Burnus]

On 10.02.22 11:07, Roger Sayle wrote:

> The fix is to tweak trans-common.cc to respect the target's NO_DOT_IN_LABEL
> (and NO_DOLLAR_IN_LABEL) when generating internal equiv.%d symbols.

In general, I think the patch is okay – but as '_' is a valid identifier
and with -fdollar-ok '$' is valid as well, I wonder whether there should
be a prefix and/or a capital letter. Namely:

+#if !defined (NO_DOT_IN_LABEL)
+#define GFC_EQUIV_FMT "equiv.%d"
+#elif !defined (NO_DOLLAR_IN_LABEL)
+#define GFC_EQUIV_FMT "equiv$%d"
+#else
+#define GFC_EQUIV_FMT "equiv_%d"
+#endif

The first one we want to keep as is for backwards compatibility. And
the '.' is fine in this regard. But I think for the other two, we need
to do more, e.g., '_Equiv' + '$%d' / '_%d'. The '_' and capital letter
should place everything into the compiler namespace (in terms of C/C++)
and Fortran itself requires for a name (case insensitive, lower cased by
gfortran): [A-Z][A-Z0-9_]* – thus, '_E' contains two characters not
accessible in a normal Fortran program (ignoring bind(C,name="...").

If the _Equiv[_$]%d sounds sensible to you: Please change; if not,
what concerns do you have?

> Ok for mainline?
OK with changing the prefix for the non-dot variant.

Tobias

> 2022-02-10  Roger Sayle  <roger@nextmovesoftware.com>
>
> gcc/fortran/ChangeLog
>       * trans-common.cc (GFC_EQUIV_FMT): New macro respecting the
>       target's NO_DOT_IN_LABEL and NO_DOLLAR_IN_LABEL preferences.
>       (build_equiv_decl): Use GFC_EQUIV_FMT here.

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