[backport from gcc-4.7/trunk r182922 <mikpe@it.uu.se>]

gcc/

2012-01-05  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/51767
	* cfgrtl.c (force_nonfallthru_and_redirect): Force addition
	of jump_block and add an extra edge for degenerated asm gotos.

gcc/testsuite/

2012-01-05  Jakub Jelinek  <jakub@redhat.com>

	PR rtl-optimization/51767
	* gcc.c-torture/compile/pr51767.c: New test.

--- gcc-4.6.2/gcc/cfgrtl.c.~1~	2010-11-19 19:56:01.000000000 +0100
+++ gcc-4.6.2/gcc/cfgrtl.c	2012-01-18 15:30:38.000000000 +0100
@@ -1123,6 +1123,7 @@ force_nonfallthru_and_redirect (edge e, 
   rtx note;
   edge new_edge;
   int abnormal_edge_flags = 0;
+  bool asm_goto_edge = false;
   int loc;
 
   /* In the case the last instruction is conditional jump to the next
@@ -1202,8 +1203,28 @@ force_nonfallthru_and_redirect (edge e, 
 	}
     }
 
-  if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags)
+  /* If e->src ends with asm goto, see if any of the ASM_OPERANDS_LABELs
+     don't point to target label.  */
+  if (JUMP_P (BB_END (e->src))
+      && target != EXIT_BLOCK_PTR
+      && e->dest == target
+      && (e->flags & EDGE_FALLTHRU)
+      && (note = extract_asm_operands (PATTERN (BB_END (e->src)))))
     {
+      int i, n = ASM_OPERANDS_LABEL_LENGTH (note);
+
+      for (i = 0; i < n; ++i)
+	if (XEXP (ASM_OPERANDS_LABEL (note, i), 0) == BB_HEAD (target))
+	  {
+	    asm_goto_edge = true;
+	    break;
+	  }
+    }
+
+  if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags || asm_goto_edge)
+    {
+      gcov_type count = e->count;
+      int probability = e->probability;
       /* Create the new structures.  */
 
       /* If the old block ended with a tablejump, skip its table
@@ -1214,7 +1235,7 @@ force_nonfallthru_and_redirect (edge e, 
       note = NEXT_INSN (note);
 
       jump_block = create_basic_block (note, NULL, e->src);
-      jump_block->count = e->count;
+      jump_block->count = count;
       jump_block->frequency = EDGE_FREQUENCY (e);
       jump_block->loop_depth = target->loop_depth;
 
@@ -1230,13 +1251,27 @@ force_nonfallthru_and_redirect (edge e, 
 
       /* Wire edge in.  */
       new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
-      new_edge->probability = e->probability;
-      new_edge->count = e->count;
+      new_edge->probability = probability;
+      new_edge->count = count;
 
       /* Redirect old edge.  */
       redirect_edge_pred (e, jump_block);
       e->probability = REG_BR_PROB_BASE;
 
+      /* If asm goto has any label refs to target's label,
+	 add also edge from asm goto bb to target.  */
+      if (asm_goto_edge)
+	{
+	  new_edge->probability /= 2;
+	  new_edge->count /= 2;
+	  jump_block->count /= 2;
+	  jump_block->frequency /= 2;
+	  new_edge = make_edge (new_edge->src, target,
+				e->flags & ~EDGE_FALLTHRU);
+	  new_edge->probability = probability - probability / 2;
+	  new_edge->count = count - count / 2;
+	}
+
       new_bb = jump_block;
     }
   else
--- gcc-4.6.2/gcc/testsuite/gcc.c-torture/compile/pr51767.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.6.2/gcc/testsuite/gcc.c-torture/compile/pr51767.c	2012-01-18 15:30:38.000000000 +0100
@@ -0,0 +1,23 @@
+/* PR rtl-optimization/51767 */
+
+extern void fn1 (void), fn2 (void);
+
+static inline __attribute__((always_inline)) int
+foo (int *x, long y)
+{
+  asm goto ("" : : "r" (x), "r" (y) : "memory" : lab);
+  return 0;
+lab:
+  return 1;
+}
+
+void
+bar (int *x)
+{
+  if (foo (x, 23))
+    fn1 ();
+  else
+    fn2 ();
+
+  foo (x, 2);
+}