final.c (shorten_branches): Do not align labels for jump tables.

	* final.c (shorten_branches): Do not align labels for jump tables.
	(final_scan_insn): Use JUMP_TABLE_DATA_P.

	* gcc.dg/falign-labels-1.c: New test.

Co-Authored-By: Maxim Kuvyrkov <maxim@codesourcery.com>

From-SVN: r147824

gcc/ChangeLog

+2009-05-23  Mark Mitchell  <mark@codesourcery.com>
+
+	* final.c (shorten_branches): Do not align labels for jump tables.
+	(final_scan_insn): Use JUMP_TABLE_DATA_P.
+
 2009-05-23  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* doc/passes.texi: Standardize spelling of RTL, Tree and Tree SSA.

gcc/final.c

@@ -901,6 +901,7 @@ shorten_branches (rtx first ATTRIBUTE_UNUSED)
       if (LABEL_P (insn))
 	{
 	  rtx next;
+	  bool next_is_jumptable;
 
 	  /* Merge in alignments computed by compute_alignments.  */
 	  log = LABEL_TO_ALIGNMENT (insn);
@@ -910,22 +911,22 @@ shorten_branches (rtx first ATTRIBUTE_UNUSED)
 	      max_skip = LABEL_TO_MAX_SKIP (insn);
 	    }
 
+	  next = next_nonnote_insn (insn);
+	  next_is_jumptable = next && JUMP_TABLE_DATA_P (next);
+	  if (!next_is_jumptable)
+	    {
 	      log = LABEL_ALIGN (insn);
 	      if (max_log < log)
 		{
 		  max_log = log;
 		  max_skip = LABEL_ALIGN_MAX_SKIP;
 		}
-	  next = next_nonnote_insn (insn);
+	    }
 	  /* ADDR_VECs only take room if read-only data goes into the text
 	     section.  */
-	  if (JUMP_TABLES_IN_TEXT_SECTION
+	  if ((JUMP_TABLES_IN_TEXT_SECTION
 	       || readonly_data_section == text_section)
-	    if (next && JUMP_P (next))
-	      {
-		rtx nextbody = PATTERN (next);
-		if (GET_CODE (nextbody) == ADDR_VEC
-		    || GET_CODE (nextbody) == ADDR_DIFF_VEC)
+	      && next_is_jumptable)
 	    {
 	      log = ADDR_VEC_ALIGN (next);
 	      if (max_log < log)
@@ -934,7 +935,6 @@ shorten_branches (rtx first ATTRIBUTE_UNUSED)
 		  max_skip = LABEL_ALIGN_MAX_SKIP;
 		}
 	    }
-	      }
 	  LABEL_TO_ALIGNMENT (insn) = max_log;
 	  LABEL_TO_MAX_SKIP (insn) = max_skip;
 	  max_log = 0;
@@ -2023,16 +2023,10 @@ final_scan_insn (rtx insn, FILE *file, int optimize ATTRIBUTE_UNUSED,
       app_disable ();
 
       next = next_nonnote_insn (insn);
-      if (next != 0 && JUMP_P (next))
-	{
-	  rtx nextbody = PATTERN (next);
-
-	  /* If this label is followed by a jump-table,
-	     make sure we put the label in the read-only section.  Also
-	     possibly write the label and jump table together.  */
-
-	  if (GET_CODE (nextbody) == ADDR_VEC
-	      || GET_CODE (nextbody) == ADDR_DIFF_VEC)
+      /* If this label is followed by a jump-table, make sure we put
+	 the label in the read-only section.  Also possibly write the
+	 label and jump table together.  */
+      if (next != 0 && JUMP_TABLE_DATA_P (next))
 	{
 #if defined(ASM_OUTPUT_ADDR_VEC) || defined(ASM_OUTPUT_ADDR_DIFF_VEC)
 	  /* In this case, the case vector is being moved by the
@@ -2065,7 +2059,6 @@ final_scan_insn (rtx insn, FILE *file, int optimize ATTRIBUTE_UNUSED,
 #endif
 	  break;
 	}
-	}
       if (LABEL_ALT_ENTRY_P (insn))
 	output_alternate_entry_point (file, insn);
       else

gcc/testsuite/ChangeLog

+2009-05-23  Mark Mitchell  <mark@codesourcery.com>
+	    Maxim Kuvyrkov  <maxim@codesourcery.com>
+
+	* gcc.dg/falign-labels-1.c: New test.
+
 2009-05-23  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gnat.dg/specs/rep_clause3.ads: New test.

gcc/testsuite/gcc.dg/falign-labels-1.c

+/* { dg-do run } */
+/* { dg-options "-falign-labels=8" { target { ! { m68k*-*-* || fido*-*-* } } } } */
+
+/* On ARMv7-A CPUs, this test resulted in incorrect code generation.
+   The code generated for the switch statement expected the jump table
+   to immediately follow the jump instruction, but -falign-labels
+   caused the label preceding the table to be aligned.  */
+/* M68K and fido only support -falign-labels argument <= 2.  */
+
+volatile int x;
+
+int main(void)
+{
+  int y;
+
+  x = 0;
+
+  switch(x)
+    {
+    case 0:
+      y = 2 * x;
+      break;
+    case 1:
+      y = -3 * x;
+      break;
+    case 2:
+      y = x + 5;
+      break;
+    case 3:
+      y = x - 7;
+      break;
+    default:
+      break;
+    }
+
+  x = y;
+
+  return 0;
+}