[PATCH] Fix PR70740

[Richard Biener]

I am testing the following patch to fix PR70740.

Bootstrap/regtest running on x86_64-unknown-linux-gnu.

Richard.

2016-04-21  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/70740
        * tree-ssa-phiprop.c (propagate_with_phi): Handle inserted
        VDEF.

        * gcc.dg/torture/pr70740.c: New testcase.

Index: gcc/tree-ssa-phiprop.c
===================================================================
*** gcc/tree-ssa-phiprop.c      (revision 235305)
--- gcc/tree-ssa-phiprop.c      (working copy)
*************** propagate_with_phi (basic_block bb, gphi
*** 327,339 ****
        continue;
  
        /* Check if we can move the loads.  The def stmt of the virtual use
!        needs to be in a different basic block dominating bb.  */
        vuse = gimple_vuse (use_stmt);
        def_stmt = SSA_NAME_DEF_STMT (vuse);
        if (!SSA_NAME_IS_DEFAULT_DEF (vuse)
          && (gimple_bb (def_stmt) == bb
!             || !dominated_by_p (CDI_DOMINATORS,
!                                 bb, gimple_bb (def_stmt))))
        goto next;
  
        /* Found a proper dereference with an aggregate copy.  Just
--- 327,341 ----
        continue;
  
        /* Check if we can move the loads.  The def stmt of the virtual use
!        needs to be in a different basic block dominating bb.  When the
!        def is an edge-inserted one we know it dominates us.  */
        vuse = gimple_vuse (use_stmt);
        def_stmt = SSA_NAME_DEF_STMT (vuse);
        if (!SSA_NAME_IS_DEFAULT_DEF (vuse)
          && (gimple_bb (def_stmt) == bb
!             || (gimple_bb (def_stmt)
!                 && !dominated_by_p (CDI_DOMINATORS,
!                                     bb, gimple_bb (def_stmt)))))
        goto next;
  
        /* Found a proper dereference with an aggregate copy.  Just
Index: gcc/testsuite/gcc.dg/torture/pr70740.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr70740.c      (revision 0)
--- gcc/testsuite/gcc.dg/torture/pr70740.c      (working copy)
***************
*** 0 ****
--- 1,38 ----
+ /* { dg-do compile } */
+ 
+ extern int foo (void);
+ extern void *memcpy (void *, const void *, __SIZE_TYPE__);
+ 
+ struct
+ {
+   char a[6];
+ } d;
+ struct
+ {
+   int a1[0];
+   int a2[0];
+   int a3[0];
+   int a4[];
+ } a, c;
+ int b;
+ 
+ int *
+ bar ()
+ {
+   if (b)
+     return a.a4;
+   return a.a2;
+ }
+ 
+ void
+ baz ()
+ {
+   int *e, *f;
+   if (foo ())
+     e = c.a3;
+   else
+     e = c.a1;
+   memcpy (d.a, e, 6);
+   f = bar ();
+   memcpy (d.a, f, 1);
+ }