[PATCH] rs6000: Don't forget to initialize the TOC (PR77957)

[Segher Boessenkool]

The code generating traceback tables mistakenly does an early return
if !optional_tbtab, which causes it to miss the code generating the TOC
section.  This only matters if the TOC will be empty since otherwise
the section is created elsewhere.

This patch fixes it.  It will need a backport to 6 as well, and
although I couldn't get it to fail with 5 the code has the same problem
there.

Tested on powerpc64-linux {-m32,-m64}; committing to trunk.

(The patch looks much bigger than it is, it is mostly a reindent).


Segher


2016-11-12  Segher Boessenkool  <segher@kernel.crashing.org>

	PR target/77957
	* config/rs6000/rs6000.c (rs6000_output_function_epilogue): Don't
	return early if !optional_tbtab.

---
 gcc/config/rs6000/rs6000.c | 77 +++++++++++++++++++++++-----------------------
 1 file changed, 39 insertions(+), 38 deletions(-)

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 03f81a8..bab4dfc 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -30320,53 +30320,54 @@ rs6000_output_function_epilogue (FILE *file,
 	 seems to set the bit when not optimizing.  */
       fprintf (file, "%d\n", ((float_parms << 1) | (! optimize)));
 
-      if (! optional_tbtab)
-	return;
+      if (optional_tbtab)
+	{
+	  /* Optional fields follow.  Some are variable length.  */
 
-      /* Optional fields follow.  Some are variable length.  */
+	  /* Parameter types, left adjusted bit fields: 0 fixed, 10 single
+	     float, 11 double float.  */
+	  /* There is an entry for each parameter in a register, in the order
+	     that they occur in the parameter list.  Any intervening arguments
+	     on the stack are ignored.  If the list overflows a long (max
+	     possible length 34 bits) then completely leave off all elements
+	     that don't fit.  */
+	  /* Only emit this long if there was at least one parameter.  */
+	  if (fixed_parms || float_parms)
+	    fprintf (file, "\t.long %d\n", parm_info);
 
-      /* Parameter types, left adjusted bit fields: 0 fixed, 10 single float,
-	 11 double float.  */
-      /* There is an entry for each parameter in a register, in the order that
-	 they occur in the parameter list.  Any intervening arguments on the
-	 stack are ignored.  If the list overflows a long (max possible length
-	 34 bits) then completely leave off all elements that don't fit.  */
-      /* Only emit this long if there was at least one parameter.  */
-      if (fixed_parms || float_parms)
-	fprintf (file, "\t.long %d\n", parm_info);
+	  /* Offset from start of code to tb table.  */
+	  fputs ("\t.long ", file);
+	  ASM_OUTPUT_INTERNAL_LABEL_PREFIX (file, "LT");
+	  RS6000_OUTPUT_BASENAME (file, fname);
+	  putc ('-', file);
+	  rs6000_output_function_entry (file, fname);
+	  putc ('\n', file);
 
-      /* Offset from start of code to tb table.  */
-      fputs ("\t.long ", file);
-      ASM_OUTPUT_INTERNAL_LABEL_PREFIX (file, "LT");
-      RS6000_OUTPUT_BASENAME (file, fname);
-      putc ('-', file);
-      rs6000_output_function_entry (file, fname);
-      putc ('\n', file);
+	  /* Interrupt handler mask.  */
+	  /* Omit this long, since we never set the interrupt handler bit
+	     above.  */
 
-      /* Interrupt handler mask.  */
-      /* Omit this long, since we never set the interrupt handler bit
-	 above.  */
+	  /* Number of CTL (controlled storage) anchors.  */
+	  /* Omit this long, since the has_ctl bit is never set above.  */
 
-      /* Number of CTL (controlled storage) anchors.  */
-      /* Omit this long, since the has_ctl bit is never set above.  */
+	  /* Displacement into stack of each CTL anchor.  */
+	  /* Omit this list of longs, because there are no CTL anchors.  */
 
-      /* Displacement into stack of each CTL anchor.  */
-      /* Omit this list of longs, because there are no CTL anchors.  */
+	  /* Length of function name.  */
+	  if (*fname == '*')
+	    ++fname;
+	  fprintf (file, "\t.short %d\n", (int) strlen (fname));
 
-      /* Length of function name.  */
-      if (*fname == '*')
-	++fname;
-      fprintf (file, "\t.short %d\n", (int) strlen (fname));
+	  /* Function name.  */
+	  assemble_string (fname, strlen (fname));
 
-      /* Function name.  */
-      assemble_string (fname, strlen (fname));
+	  /* Register for alloca automatic storage; this is always reg 31.
+	     Only emit this if the alloca bit was set above.  */
+	  if (frame_pointer_needed)
+	    fputs ("\t.byte 31\n", file);
 
-      /* Register for alloca automatic storage; this is always reg 31.
-	 Only emit this if the alloca bit was set above.  */
-      if (frame_pointer_needed)
-	fputs ("\t.byte 31\n", file);
-
-      fputs ("\t.align 2\n", file);
+	  fputs ("\t.align 2\n", file);
+	}
     }
 
   /* Arrange to define .LCTOC1 label, if not already done.  */
-- 
1.9.3