[PATCH] Fix PR tree-opt/38865 missing FRE with VIEW_CONVERT_EXPR

[Andrew Pinski]

Hi,
  The issue here is that we have:
  sv_1(D)->i = { 0, 0, 0, 0 };
  D.1242_2 = VIEW_CONVERT_EXPR<vector float>(sv_1(D)->i);

And FRE/PRE does not see that it could look through the VCE even
though we could.

This patch allows SCCVN to look through the VCE.

OK?  Bootstrapped and tested on i686-linux-gnu with no regressions.

Thanks,
Andrew Pinski

ChangeLog:
* tree-ssa-sccvn.c (visit_reference_op_load): If vn_reference_lookup
is returns NULL and OP is a VCE, look through the VCE.
(visit_reference_op_store): Unwrap the VCE.

* gcc.dg/tree-ssa/fre-vce-1.c: New testcase.
-------------- next part --------------
Index: tree-ssa-sccvn.c
===================================================================
--- tree-ssa-sccvn.c	(revision 146612)
+++ tree-ssa-sccvn.c	(working copy)
@@ -1700,6 +1700,12 @@
   bool changed = false;
   tree result = vn_reference_lookup (op, gimple_vuse (stmt), true, NULL);
 
+  /* If we have a VCE, try looking up its operand as it might be stored in
+     a different type.  */
+  if (!result && TREE_CODE (op) == VIEW_CONVERT_EXPR)
+    result = vn_reference_lookup (TREE_OPERAND (op, 0), gimple_vuse (stmt),
+    				  true, NULL);
+
   /* We handle type-punning through unions by value-numbering based
      on offset and size of the access.  Be prepared to handle a
      type-mismatch here via creating a VIEW_CONVERT_EXPR.  */
@@ -1793,6 +1799,10 @@
   tree result;
   bool resultsame = false;
 
+  /* If the lhs is a VCE, look past it. */
+  if (TREE_CODE (lhs) == VIEW_CONVERT_EXPR)
+    lhs = TREE_OPERAND (lhs, 0);
+
   /* First we want to lookup using the *vuses* from the store and see
      if there the last store to this location with the same address
      had the same value.
Index: testsuite/gcc.dg/tree-ssa/fre-vce-1.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/fre-vce-1.c	(revision 0)
+++ testsuite/gcc.dg/tree-ssa/fre-vce-1.c	(revision 0)
@@ -0,0 +1,35 @@
+/* { dg-options "-O2 -fdump-tree-fre -w" } */
+/* { dg-do compile } */
+#define vector __attribute__((vector_size(sizeof(int)*4) ))
+struct s { vector int i; };
+vector float f(struct s *sv)
+{
+  sv->i = (vector int){0, 0, 0, 0};
+  return (vector float)sv->i;
+}
+
+
+vector float f1(struct s *sv, vector int a)
+{
+  sv->i = a;
+  return (vector float)sv->i;
+}
+
+struct s1 { int i; };
+
+void g(struct s1 *, float);
+void a1 (struct s1 sv)
+{
+  sv.i = 0;
+  g(&sv, *(float*)&sv.i);
+}
+
+
+void a2 (struct s1 sv, int i)
+{
+  sv.i = i;
+  g(&sv, *(float*)&sv.i);
+}
+
+/* { dg-final { scan-tree-dump-times 2 "fre" "sv_\[0-9\]\\\(D\\\)->i" } } */
+/* { dg-final { scan-tree-dump-times 2 "fre" "sv.i" } } */