re PR middle-end/39284 (Computed gotos combined too aggressively)

        PR target/39284
        * passes.def (peephole2): Move peephole2 pass before
        before sched2 pass.
        * config/i386/i386.md (peehole2): Combine memories
        and indirect jumps.

From-SVN: r211919

gcc/ChangeLog

+2014-06-23  Kai Tietz  <ktietz@redhat.com>
+
+	PR target/39284
+	* passes.def (peephole2): Move peephole2 pass before
+	before sched2 pass.
+	* config/i386/i386.md (peehole2): Combine memories
+	and indirect jumps.
+
 2014-06-23  Richard Biener  <rguenther@suse.de>
 
 	* tree-ssa-loop.c (gate_loop): New function.

gcc/config/i386/i386.md

@@ -11466,6 +11466,15 @@
 			    (match_dup 4)))
 	      (unspec [(const_int 0)] UNSPEC_PEEPSIB)])])
 
+;; Combining simple memory jump instruction
+
+(define_peephole2
+  [(set (match_operand:W 0 "register_operand")
+        (match_operand:W 1 "memory_operand"))
+   (set (pc) (match_dup 0))]
+  "!TARGET_X32 && peep2_reg_dead_p (2, operands[0])"
+  [(set (pc) (match_dup 1))])
+
 ;; Call subroutine, returning value in operand 0
 
 (define_expand "call_value"

gcc/passes.def

@@ -394,13 +394,20 @@ along with GCC; see the file COPYING3.  If not see
 	  NEXT_PASS (pass_rtl_dse2);
 	  NEXT_PASS (pass_stack_adjustments);
 	  NEXT_PASS (pass_jump2);
-	  NEXT_PASS (pass_peephole2);
 	  NEXT_PASS (pass_if_after_reload);
 	  NEXT_PASS (pass_regrename);
 	  NEXT_PASS (pass_cprop_hardreg);
 	  NEXT_PASS (pass_fast_rtl_dce);
 	  NEXT_PASS (pass_duplicate_computed_gotos);
 	  NEXT_PASS (pass_reorder_blocks);
+	  /* We need to run peephole2 pass after the duplicate-
+	     compute-gotos and the reorder-blocks pass (PR/39284).
+	     We have a single indirect branch in the entire function
+	     before duplicate-compute-gotos pass.  This vastly reduces
+	     the size of the CFG.
+	     For preventing to run peephole2 pass twice, its run after
+	     the jump2 got removed.  */
+	  NEXT_PASS (pass_peephole2);
 	  NEXT_PASS (pass_branch_target_load_optimize2);
 	  NEXT_PASS (pass_leaf_regs);
 	  NEXT_PASS (pass_split_before_sched2);