[PATCH][5/4] Fix PR87117

[Richard Biener]

Another one.

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

Richard.

2018-08-28  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/87117
        * tree-ssa-sccvn.c (eliminate_dom_walker::eliminate_stmt): Only
        re-value-number released SSA VDEFs.

        * gfortran.dg/pr87117.f90: New testcase.

Index: gcc/tree-ssa-sccvn.c
===================================================================
--- gcc/tree-ssa-sccvn.c        (revision 263917)
+++ gcc/tree-ssa-sccvn.c        (working copy)
@@ -4979,8 +4979,14 @@ eliminate_dom_walker::eliminate_stmt (ba
          propagate_tree_value_into_stmt (gsi, sprime);
          stmt = gsi_stmt (*gsi);
          update_stmt (stmt);
+         /* In case the VDEF on the original stmt was released, value-number
+            it to the VUSE.  This is to make vuse_ssa_val able to skip
+            released virtual operands.  */
          if (vdef != gimple_vdef (stmt))
-           VN_INFO (vdef)->valnum = vuse;
+           {
+             gcc_assert (SSA_NAME_IN_FREE_LIST (vdef));
+             VN_INFO (vdef)->valnum = vuse;
+           }
 
          /* If we removed EH side-effects from the statement, clean
             its EH information.  */
@@ -5258,7 +5264,10 @@ eliminate_dom_walker::eliminate_stmt (ba
            fprintf (dump_file, "  Removed AB side-effects.\n");
        }
       update_stmt (stmt);
-      if (vdef != gimple_vdef (stmt))
+      /* In case the VDEF on the original stmt was released, value-number
+         it to the VUSE.  This is to make vuse_ssa_val able to skip
+        released virtual operands.  */
+      if (vdef && SSA_NAME_IN_FREE_LIST (vdef))
        VN_INFO (vdef)->valnum = vuse;
     }
 
Index: gcc/testsuite/gfortran.dg/pr87117.f90
===================================================================
--- gcc/testsuite/gfortran.dg/pr87117.f90       (nonexistent)
+++ gcc/testsuite/gfortran.dg/pr87117.f90       (working copy)
@@ -0,0 +1,14 @@
+! { dg-do compile }
+! { dg-options "-O" }
+program p
+   real(4) :: a, b
+   integer(4) :: n, m
+   equivalence (a, n)
+   a = 1024.0
+   m = 8
+   a = 1024.0
+   b = set_exponent(a, m)
+   n = 8
+   a = f(a, n)
+   b = set_exponent(a, m)
+end