[PATCH] Fix PR35869, bad interaction with SSA updating and switch stmt optimization

[Richard Guenther <rguenther at suse dot de>]

This fixes the bug by scheduling the switch stmt optimization after the
SSA update required before jump threading.  It also "disables" the
optimization doing only one cfg_cleanup run and schedules a second one
after the switch stmt update.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.

Richard.

2008-04-11  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/35869
	* tree-vrp.c (execute_vrp): Move switch statement update after
	jump threading.  Schedule another cfg cleanup run.

	* gcc.c-torture/compile/pr35869.c: New testcase.

Index: tree-vrp.c
===================================================================
*** tree-vrp.c	(revision 134193)
--- tree-vrp.c	(working copy)
*************** execute_vrp (void)
*** 6734,6753 ****
    ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node);
    vrp_finalize ();
  
-   /* Remove dead edges from SWITCH_EXPR optimization.  This leaves the
-      CFG in a broken state and requires a cfg_cleanup run.  */
-   for (i = 0; VEC_iterate (edge, to_remove_edges, i, e); ++i)
-     remove_edge (e);
-   /* Update SWITCH_EXPR case label vector.  */
-   for (i = 0; VEC_iterate (switch_update, to_update_switch_stmts, i, su); ++i)
-     SWITCH_LABELS (su->stmt) = su->vec;
- 
-   if (VEC_length (edge, to_remove_edges) > 0)
-     free_dominance_info (CDI_DOMINATORS);
- 
-   VEC_free (edge, heap, to_remove_edges);
-   VEC_free (switch_update, heap, to_update_switch_stmts);
- 
    /* ASSERT_EXPRs must be removed before finalizing jump threads
       as finalizing jump threads calls the CFG cleanup code which
       does not properly handle ASSERT_EXPRs.  */
--- 6734,6739 ----
*************** execute_vrp (void)
*** 6761,6766 ****
--- 6747,6770 ----
    update_ssa (TODO_update_ssa);
  
    finalize_jump_threads ();
+ 
+   /* Remove dead edges from SWITCH_EXPR optimization.  This leaves the
+      CFG in a broken state and requires a cfg_cleanup run.  */
+   for (i = 0; VEC_iterate (edge, to_remove_edges, i, e); ++i)
+     remove_edge (e);
+   /* Update SWITCH_EXPR case label vector.  */
+   for (i = 0; VEC_iterate (switch_update, to_update_switch_stmts, i, su); ++i)
+     SWITCH_LABELS (su->stmt) = su->vec;
+ 
+   if (VEC_length (edge, to_remove_edges) > 0)
+     {
+       free_dominance_info (CDI_DOMINATORS);
+       cleanup_tree_cfg ();
+     }
+ 
+   VEC_free (edge, heap, to_remove_edges);
+   VEC_free (switch_update, heap, to_update_switch_stmts);
+ 
    scev_finalize ();
    loop_optimizer_finalize ();
  
Index: testsuite/gcc.c-torture/compile/pr35869.c
===================================================================
*** testsuite/gcc.c-torture/compile/pr35869.c	(revision 0)
--- testsuite/gcc.c-torture/compile/pr35869.c	(revision 0)
***************
*** 0 ****
--- 1,47 ----
+ struct texture_stage_op
+ {
+     unsigned int carg1, carg2, carg0;
+     unsigned int aarg1, aarg2, aarg0;
+     unsigned int dst;
+ };
+ 
+ static const char *debug_register(unsigned int reg) {
+     switch(reg) {
+         case 0x8921: return "GL_REG_0_ATI";
+         case 0x8923: return "GL_REG_2_ATI";
+         case 0x0: return "GL_ZERO";
+         case 0x1: return "GL_ONE";
+         default: return "Unknown register\n";
+     }
+ }
+ 
+ static unsigned int find_tmpreg(struct texture_stage_op op[8]) {
+     int i;
+     int tex_used[8];
+ 
+     for(i = 0; i < 8; i++) {
+         if(op[i].carg1 == 0x00000002 ) {
+             tex_used[i] = 1;
+         }
+     }
+ 
+     for(i = 1; i < 6; i++) {
+         if(!tex_used[i]) {
+                 return 0x8921 + i;
+         }
+     }
+     return 0;
+ }
+ 
+ extern f(const char*);
+ 
+ void g() {
+     struct texture_stage_op op[8];
+     unsigned int tmparg = find_tmpreg(op);
+     unsigned int dstreg;
+ 
+     if(tmparg == 0x0) return;
+     dstreg = tmparg;
+     f(debug_register(dstreg));
+     return;
+ }