Re: [patch] Default to --enable-libstdcxx-time=auto

[Rainer Orth <ro at CeBiTec dot Uni-Bielefeld dot DE>]

Jakub Jelinek <jakub@redhat.com> writes:

>> It occured to me that there might be a far less intrusive option to still
>> allow a Solaris backport: instead of going the libstdc++.spec route
>> (which I still think is the correct way forward), statically handle -lrt
>> addition in g++spec.c, controlled by a macro defined only in config/sol2.h.
>> 
>> Such a patch could be added to mainline and 4.8 branch now, and mainline
>> later changed to use libstdc++.spec instead.
>
> I think a switch from not linking libstdc++ against -lrt to linking against
> that is quite heavy change for the branch.  Do you see why the latest patch

I'm not so sure: to me, that's just an implementation detail.

> I've posted today wouldn't work well on Solaris?

It should work on the 4.8 branch (I'll include it in my bootstraps this
weekend), but on mainline the failures due to missing nanosleep/-lrt
will remain.

I've just successfully bootstrapped the following patch on
i386-pc-solaris2.10 and x86_64-unknown-linux-gnu.  It fixes the
libstdc++ testsuite failures I'd reported before.

	Rainer


2013-05-24  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	gcc/cp:
	* g++spec.c (TIMELIB): Define.
	(WITHLIBC, SKIPOPT): Adjust values.
	(lang_specific_driver): Add TIME_LIBRARY if not passed explicitly.

	gcc:
	* config/sol2.h (TIME_LIBRARY): Define.

# HG changeset patch
# Parent d6881ec042d3a6328b763cbf0f38e61bdbb64d79
Add -lrt on Solaris

diff --git a/gcc/config/sol2.h b/gcc/config/sol2.h
--- a/gcc/config/sol2.h
+++ b/gcc/config/sol2.h
@@ -194,6 +194,9 @@ along with GCC; see the file COPYING3.  
 #endif /* HAVE_LD_EH_FRAME && TARGET_DL_ITERATE_PHDR */
 #endif
 
+/* C++11 programs need -lrt for nanosleep.  */
+#define TIME_LIBRARY "rt"
+
 #ifndef USE_GLD
 /* The default MFLIB_SPEC is GNU ld specific.  */
 #define MFLIB_SPEC ""
diff --git a/gcc/cp/g++spec.c b/gcc/cp/g++spec.c
--- a/gcc/cp/g++spec.c
+++ b/gcc/cp/g++spec.c
@@ -28,10 +28,12 @@ along with GCC; see the file COPYING3.  
 #define LANGSPEC	(1<<1)
 /* This bit is set if they did `-lm' or `-lmath'.  */
 #define MATHLIB		(1<<2)
+/* This bit is set if they did `-lrt' or equivalent.  */
+#define TIMELIB		(1<<3)
 /* This bit is set if they did `-lc'.  */
-#define WITHLIBC	(1<<3)
+#define WITHLIBC	(1<<4)
 /* Skip this option.  */
-#define SKIPOPT		(1<<4)
+#define SKIPOPT		(1<<5)
 
 #ifndef MATH_LIBRARY
 #define MATH_LIBRARY "m"
@@ -40,6 +42,10 @@ along with GCC; see the file COPYING3.  
 #define MATH_LIBRARY_PROFILE MATH_LIBRARY
 #endif
 
+#ifndef TIME_LIBRARY
+#define TIME_LIBRARY ""
+#endif
+
 #ifndef LIBSTDCXX
 #define LIBSTDCXX "stdc++"
 #endif
@@ -83,16 +89,22 @@ lang_specific_driver (struct cl_decoded_
   /* "-lm" or "-lmath" if it appears on the command line.  */
   const struct cl_decoded_option *saw_math = NULL;
 
+  /* "-lrt" or eqivalent if it appears on the command line.  */
+  const struct cl_decoded_option *saw_time = NULL;
+
   /* "-lc" if it appears on the command line.  */
   const struct cl_decoded_option *saw_libc = NULL;
 
   /* An array used to flag each argument that needs a bit set for
-     LANGSPEC, MATHLIB, or WITHLIBC.  */
+     LANGSPEC, MATHLIB, TIMELIB, or WITHLIBC.  */
   int *args;
 
   /* By default, we throw on the math library if we have one.  */
   int need_math = (MATH_LIBRARY[0] != '\0');
 
+  /* By default, we throw on the time library if we have one.  */
+  int need_time = (TIME_LIBRARY[0] != '\0');
+
   /* True if we saw -static.  */
   int static_link = 0;
 
@@ -136,6 +148,11 @@ lang_specific_driver (struct cl_decoded_
 	      args[i] |= MATHLIB;
 	      need_math = 0;
 	    }
+	  else if (strcmp (arg, TIME_LIBRARY) == 0)
+	    {
+	      args[i] |= TIMELIB;
+	      need_time = 0;
+	    }
 	  else if (strcmp (arg, "c") == 0)
 	    args[i] |= WITHLIBC;
 	  else
@@ -268,6 +285,12 @@ lang_specific_driver (struct cl_decoded_
 	  saw_math = &decoded_options[i];
 	}
 
+      if (!saw_time && (args[i] & TIMELIB) && library > 0)
+	{
+	  --j;
+	  saw_time = &decoded_options[i];
+	}
+
       if (!saw_libc && (args[i] & WITHLIBC) && library > 0)
 	{
 	  --j;
@@ -352,6 +375,15 @@ lang_specific_driver (struct cl_decoded_
       added_libraries++;
       j++;
     }
+  if (saw_time)
+    new_decoded_options[j++] = *saw_time;
+  else if (library > 0 && need_time)
+    {
+      generate_option (OPT_l, TIME_LIBRARY, 1, CL_DRIVER,
+		       &new_decoded_options[j]);
+      added_libraries++;
+      j++;
+    }
   if (saw_libc)
     new_decoded_options[j++] = *saw_libc;
   if (shared_libgcc && !static_link)

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University