sparc.c (sparc_asm_function_epilogue): Don't output an extra nop past a sibling…

sparc.c (sparc_asm_function_epilogue): Don't output an extra nop past a sibling call at the very end.

        * config/sparc/sparc.c (sparc_asm_function_epilogue): Don't output
        an extra nop past a sibling call at the very end.

        testsuite/
        * gcc.target/sparc/sibcall-dslot.c: New testcase.

From-SVN: r163395

gcc/ChangeLog

+2010-08-20  Olivier Hainque  <hainque@adacore.com>
+
+	* config/sparc/sparc.c (sparc_asm_function_epilogue): Don't output
+	an extra nop past a sibling call at the very end.
+
 2010-08-19  Bernd Schmidt  <bernds@codesourcery.com>
 
 	PR bootstrap/45350

gcc/config/sparc/sparc.c

@@ -4527,11 +4527,11 @@ sparc_can_use_return_insn_p (void)
 static void
 sparc_asm_function_epilogue (FILE *file, HOST_WIDE_INT size ATTRIBUTE_UNUSED)
 {
-  /* If code does not drop into the epilogue, we have to still output
-     a dummy nop for the sake of sane backtraces.  Otherwise, if the
-     last two instructions of a function were "call foo; dslot;" this
-     can make the return PC of foo (i.e. address of call instruction
-     plus 8) point to the first instruction in the next function.  */
+  /* If the last two instructions of a function are "call foo; dslot;"
+     the return address might point to the first instruction in the next
+     function and we have to output a dummy nop for the sake of sane
+     backtraces in such cases.  This is pointless for sibling calls since
+     the return address is explicitly adjusted.  */
 
   rtx insn, last_real_insn;
 
@@ -4543,7 +4543,9 @@ sparc_asm_function_epilogue (FILE *file, HOST_WIDE_INT size ATTRIBUTE_UNUSED)
       && GET_CODE (PATTERN (last_real_insn)) == SEQUENCE)
     last_real_insn = XVECEXP (PATTERN (last_real_insn), 0, 0);
 
-  if (last_real_insn && GET_CODE (last_real_insn) == CALL_INSN)
+  if (last_real_insn
+      && CALL_P (last_real_insn)
+      && !SIBLING_CALL_P (last_real_insn))
     fputs("\tnop\n", file);
 
   sparc_output_deferred_case_vectors ();

gcc/testsuite/ChangeLog

+2010-10-19  Olivier Hainque  <hainque@adacore.com>
+
+	* gcc.target/sparc/sibcall-dslot.c: New testcase.
+
 2010-08-19  Jason Merrill  <jason@redhat.com>
 
 	* g++.dg/init/synth3.C: New.

gcc/testsuite/gcc.target/sparc/sibcall-dslot.c

+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+extern int one ();
+
+int some_n ()
+{
+    return one ();
+}
+
+/* { dg-final { scan-assembler-not "nop" } } */