[PATCH] Fix PR87402
Richard Biener
rguenther@suse.de
Tue Sep 25 12:59:00 GMT 2018
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
Richard.
2018-09-25 Richard Biener <rguenther@suse.de>
PR tree-optimization/87402
* tree-ssa-sccvn.c (SSA_VISITED): Remove unused function.
(visit_phi): Re-instantiate handling of supposed to be VARYING
but non-VARYING backedge value.
* gcc.dg/torture/pr87402.c: New testcase.
Index: gcc/tree-ssa-sccvn.c
===================================================================
--- gcc/tree-ssa-sccvn.c (revision 264564)
+++ gcc/tree-ssa-sccvn.c (working copy)
@@ -464,15 +464,6 @@ SSA_VAL (tree x, bool *visited = NULL)
return tem && tem->visited ? tem->valnum : x;
}
-/* Return whether X was visited. */
-
-inline bool
-SSA_VISITED (tree x)
-{
- vn_ssa_aux_t tem = vn_ssa_aux_hash->find_with_hash (x, SSA_NAME_VERSION (x));
- return tem && tem->visited;
-}
-
/* Return the SSA value of the VUSE x, supporting released VDEFs
during elimination which will value-number the VDEF to the
associated VUSE (but not substitute in the whole lattice). */
@@ -4196,7 +4187,10 @@ visit_phi (gimple *phi, bool *inserted,
}
}
- /* If we value-number a virtual operand never value-number to the
+ /* If the value we want to use is flowing over the backedge and we
+ should take it as VARYING but it has a non-VARYING value drop to
+ VARYING.
+ If we value-number a virtual operand never value-number to the
value from the backedge as that confuses the alias-walking code.
See gcc.dg/torture/pr87176.c. If the value is the same on a
non-backedge everything is OK though. */
@@ -4204,7 +4198,8 @@ visit_phi (gimple *phi, bool *inserted,
&& !seen_non_backedge
&& TREE_CODE (backedge_val) == SSA_NAME
&& sameval == backedge_val
- && SSA_NAME_IS_VIRTUAL_OPERAND (backedge_val))
+ && (SSA_NAME_IS_VIRTUAL_OPERAND (backedge_val)
+ || SSA_VAL (backedge_val) != backedge_val))
/* Note this just drops to VARYING without inserting the PHI into
the hashes. */
result = PHI_RESULT (phi);
Index: gcc/testsuite/gcc.dg/torture/pr87402.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr87402.c (nonexistent)
+++ gcc/testsuite/gcc.dg/torture/pr87402.c (working copy)
@@ -0,0 +1,33 @@
+/* { dg-do compile } */
+
+void
+xl (int co)
+{
+ int ar = 0;
+
+ if (ar != 0)
+ {
+ int pp, ll = 0;
+ int *zx;
+
+ if (co == 0)
+ {
+ }
+ else
+ {
+ zx = &pp;
+
+ if (co < 0)
+ while (co < 1)
+ {
+to:
+ while (ll < 1)
+ ++ll;
+ }
+
+ *zx = (__INTPTR_TYPE__)&ar;
+ }
+ }
+
+ goto to;
+}
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