[PATCH, PR 50622] Force a gimple operand in load_assign_lhs_subreplacements when necessary

[Martin Jambor]

Hi,

PR 50622 is an omission in load_assign_lhs_subreplacements, which
should force a gimple operand on a RHS of a gimple assignment if both
sides are new replacements of scalar types which are not gimple
registers, because they are partially modified (which can happen to
complex numbers and bit-fields).

Fixed with the patch below.  It passes bootstrap and testsuite on
x86_64-linux, I am about to do the same on the 4.6 branch because I'd
like to commit it there as well.  OK for trunk and the 4.6 branch?

Thanks,

Martin


2011-12-01  Martin Jambor  <mjam...@suse.cz>

        PR tree-optimization/50622
        * tree-sra.c (load_assign_lhs_subreplacements): Force gimple operand
        if both lacc and racc are grp_partial_lhs.

        * testsuite/g++.dg/tree-ssa/pr50622.C: New test.

Index: src/gcc/tree-sra.c
===================================================================
--- src.orig/gcc/tree-sra.c
+++ src/gcc/tree-sra.c
@@ -2692,6 +2692,10 @@ load_assign_lhs_subreplacements (struct
              rhs = get_access_replacement (racc);
              if (!useless_type_conversion_p (lacc->type, racc->type))
                rhs = fold_build1_loc (loc, VIEW_CONVERT_EXPR, lacc->type, rhs);
+
+             if (racc->grp_partial_lhs && lacc->grp_partial_lhs)
+               rhs = force_gimple_operand_gsi (old_gsi, rhs, true, NULL_TREE,
+                                               true, GSI_SAME_STMT);
            }
          else
            {
Index: src/gcc/testsuite/g++.dg/tree-ssa/pr50622.C
===================================================================
--- /dev/null
+++ src/gcc/testsuite/g++.dg/tree-ssa/pr50622.C
@@ -0,0 +1,30 @@
+// { dg-do compile }
+// { dg-options "-O2" }
+
+typedef __complex__ double Value;
+struct LorentzVector
+{
+  LorentzVector & operator+=(const LorentzVector & a) {
+    theX += a.theX;
+    theY += a.theY;
+    theZ += a.theZ;
+    theT += a.theT;
+    return *this;
+  }
+
+  Value theX;
+  Value theY;
+  Value theZ;
+  Value theT;
+};
+
+inline LorentzVector
+operator+(LorentzVector a, const LorentzVector & b) {
+  return a += b;
+}
+
+Value ex, et;
+LorentzVector sum() {
+  LorentzVector v1; v1.theX =ex; v1.theY =ex+et; v1.theZ =ex-et;   v1.theT =et;
+  return v1+v1;
+}