varasm.c (build_constant_desc): Don't share RTL in pool entries.

	* varasm.c (build_constant_desc): Don't share RTL in pool entries.
	
	* gcc.target/m68k/20090709-1.c: New.

From-SVN: r149426

gcc/ChangeLog

+2009-07-09  Maxim Kuvyrkov  <maxim@codesourcery.com>
+
+	* varasm.c (build_constant_desc): Don't share RTL in pool entries.
 
 2009-07-09  Basile Starynkevitch  <basile@starynkevitch.net>
 

gcc/testsuite/ChangeLog

+2009-07-09  Maxim Kuvyrkov  <maxim@codesourcery.com>
+
+	* gcc.target/m68k/20090709-1.c: New.
+
 2009-07-09  Dodji Seketeli  <dodji@redhat.com>
 
 	PR c++/40684

gcc/testsuite/gcc.dg/20090709-1.c

+/* { dg-do compile } */
+/* There should be 3 occurrences of .LC0 in the code:
+   one for the definition of "0",
+   one for use in test1() and
+   one for use in test2().
+   FIXME: At the moment m68k GCC does not optimize test1() to nop
+   for some reason.  */
+/* { dg-final { scan-assembler-times ".LC0" 3 } } */
+
+void dummy(char *arg);
+
+void test1(void)
+{
+  char tmp[2] = "0";
+}
+
+void test2(void)
+{
+  dummy("0");
+}

gcc/varasm.c

@@ -3208,6 +3208,10 @@ build_constant_desc (tree exp)
   set_mem_alias_set (rtl, 0);
   set_mem_alias_set (rtl, const_alias_set);
 
+  /* We cannot share RTX'es in pool entries.
+     Mark this piece of RTL as required for unsharing.  */
+  RTX_FLAG (rtl, used) = 1;
+
   /* Set flags or add text to the name to record information, such as
      that it is a local symbol.  If the name is changed, the macro
      ASM_OUTPUT_LABELREF will have to know how to strip this