diff mbox series

c-family: Avoid unnecessary work when -Wpragmas is being ignored

Message ID 20201109153852.3326479-1-ppalka@redhat.com
State New
Headers show
Series c-family: Avoid unnecessary work when -Wpragmas is being ignored | expand

Commit Message

Patrick Palka Nov. 9, 2020, 3:38 p.m. UTC 
This speeds up handle_pragma_diagnostic by avoiding computing a spelling
suggestion for an unrecognized option inside a #pragma directive when
-Wpragmas warnings are being suppressed.

In the range-v3 library, which contains many instances of

  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wpragmas"
  #pragma GCC diagnostic ignored "-Wfoo"
  ...
  #pragma GCC diagnostic pop

compile time is reduced by 33% in some of its tests.

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk?

gcc/c-family/ChangeLog:

	* c-pragma.c (handle_pragma_diagnostic): Split the
	unknown-option -Wpragmas diagnostic into a warning and a
	subsequent note containing a spelling suggestion.  Avoid
	computing the suggestion if -Wpragmas warnings are being
	suppressed.

gcc/testsuite/ChangeLog:

	* gcc.dg/pragma-diag-6.c: Adjust expected diagnostics
	appropriately.
---
 gcc/c-family/c-pragma.c              | 19 +++++++++----------
 gcc/testsuite/gcc.dg/pragma-diag-6.c |  9 ++++++---
 2 files changed, 15 insertions(+), 13 deletions(-)

Comments

Jeff Law Nov. 9, 2020, 4 p.m. UTC | #1 
On 11/9/20 8:38 AM, Patrick Palka via Gcc-patches wrote:
> This speeds up handle_pragma_diagnostic by avoiding computing a spelling
> suggestion for an unrecognized option inside a #pragma directive when
> -Wpragmas warnings are being suppressed.
>
> In the range-v3 library, which contains many instances of
>
>   #pragma GCC diagnostic push
>   #pragma GCC diagnostic ignored "-Wpragmas"
>   #pragma GCC diagnostic ignored "-Wfoo"
>   ...
>   #pragma GCC diagnostic pop
>
> compile time is reduced by 33% in some of its tests.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk?
>
> gcc/c-family/ChangeLog:
>
> 	* c-pragma.c (handle_pragma_diagnostic): Split the
> 	unknown-option -Wpragmas diagnostic into a warning and a
> 	subsequent note containing a spelling suggestion.  Avoid
> 	computing the suggestion if -Wpragmas warnings are being
> 	suppressed.
>
> gcc/testsuite/ChangeLog:
>
> 	* gcc.dg/pragma-diag-6.c: Adjust expected diagnostics
> 	appropriately.

OK

jeff
David Malcolm Nov. 10, 2020, 4:46 p.m. UTC | #2 
On Mon, 2020-11-09 at 10:38 -0500, Patrick Palka wrote:
> This speeds up handle_pragma_diagnostic by avoiding computing a
> spelling
> suggestion for an unrecognized option inside a #pragma directive when
> -Wpragmas warnings are being suppressed.
> 
> In the range-v3 library, which contains many instances of
> 
>   #pragma GCC diagnostic push
>   #pragma GCC diagnostic ignored "-Wpragmas"
>   #pragma GCC diagnostic ignored "-Wfoo"
>   ...
>   #pragma GCC diagnostic pop
> 
> compile time is reduced by 33% in some of its tests.
> 
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK
> for
> trunk?

Looks good to me.

Dave
Patrick Palka Nov. 10, 2020, 5:13 p.m. UTC | #3 
On Tue, 10 Nov 2020, David Malcolm wrote:

> On Mon, 2020-11-09 at 10:38 -0500, Patrick Palka wrote:
> > This speeds up handle_pragma_diagnostic by avoiding computing a
> > spelling
> > suggestion for an unrecognized option inside a #pragma directive when
> > -Wpragmas warnings are being suppressed.
> > 
> > In the range-v3 library, which contains many instances of
> > 
> >   #pragma GCC diagnostic push
> >   #pragma GCC diagnostic ignored "-Wpragmas"
> >   #pragma GCC diagnostic ignored "-Wfoo"
> >   ...
> >   #pragma GCC diagnostic pop
> > 
> > compile time is reduced by 33% in some of its tests.
> > 
> > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK
> > for
> > trunk?
> 
> Looks good to me.

Thanks David & Jeff.  Patch committed to trunk as r11-4849.

> 
> Dave
> 
>
diff mbox series

Patch

diff --git a/gcc/c-family/c-pragma.c b/gcc/c-family/c-pragma.c
index dc52ee8b003..d68985ca277 100644
--- a/gcc/c-family/c-pragma.c
+++ b/gcc/c-family/c-pragma.c
@@ -809,16 +809,15 @@  handle_pragma_diagnostic(cpp_reader *ARG_UNUSED(dummy))
   unsigned int option_index = find_opt (option_string + 1, lang_mask);
   if (option_index == OPT_SPECIAL_unknown)
     {
-      option_proposer op;
-      const char *hint = op.suggest_option (option_string + 1);
-      if (hint)
-	warning_at (loc, OPT_Wpragmas,
-		    "unknown option after %<#pragma GCC diagnostic%> kind;"
-		    " did you mean %<-%s%>?", hint);
-      else
-	warning_at (loc, OPT_Wpragmas,
-		    "unknown option after %<#pragma GCC diagnostic%> kind");
-
+      auto_diagnostic_group d;
+      if (warning_at (loc, OPT_Wpragmas,
+		      "unknown option after %<#pragma GCC diagnostic%> kind"))
+	{
+	  option_proposer op;
+	  const char *hint = op.suggest_option (option_string + 1);
+	  if (hint)
+	    inform (loc, "did you mean %<-%s%>?", hint);
+	}
       return;
     }
   else if (!(cl_options[option_index].flags & CL_WARNING))
diff --git a/gcc/testsuite/gcc.dg/pragma-diag-6.c b/gcc/testsuite/gcc.dg/pragma-diag-6.c
index 0dca1dc1ef4..f2df88d245b 100644
--- a/gcc/testsuite/gcc.dg/pragma-diag-6.c
+++ b/gcc/testsuite/gcc.dg/pragma-diag-6.c
@@ -2,7 +2,10 @@ 
 #pragma GCC diagnostic error "-Wnoexcept" /* { dg-warning "is valid for C../ObjC.. but not for C" } */
 #pragma GCC diagnostic error "-fstrict-aliasing" /* { dg-warning "not an option that controls warnings" } */
 #pragma GCC diagnostic error "-Werror" /* { dg-warning "not an option that controls warnings" } */
-#pragma GCC diagnostic error "-Wvla2" /* { dg-warning "unknown option after '#pragma GCC diagnostic' kind; did you mean '-Wvla'" } */
-#pragma GCC diagnostic error "-Walla" /* { dg-warning "unknown option after '#pragma GCC diagnostic' kind; did you mean '-Wall'" } */
-#pragma GCC diagnostic warning "-Walla" /* { dg-warning "unknown option after '#pragma GCC diagnostic' kind; did you mean '-Wall'" } */
+#pragma GCC diagnostic error "-Wvla2" /* { dg-warning "unknown option after '#pragma GCC diagnostic' kind" } */
+/* { dg-message "did you mean '-Wvla'" "" { target *-*-* } .-1 } */
+#pragma GCC diagnostic error "-Walla" /* { dg-warning "unknown option after '#pragma GCC diagnostic' kind" } */
+/* { dg-message "did you mean '-Wall'" "" { target *-*-* } .-1 } */
+#pragma GCC diagnostic warning "-Walla" /* { dg-warning "unknown option after '#pragma GCC diagnostic' kind" } */
+/* { dg-message "did you mean '-Wall'" "" { target *-*-* } .-1 } */
 int i;