[PATCH][match-and-simplify] Properly canonicalize operand order for sub-expressions
Richard Biener
rguenther@suse.de
Fri Jul 3 10:13:00 GMT 2015
I observed that we fail to match patterns because when valueizing
sub-expression operands we fail to canonicalize operand order
and thus try matching (1 + a) - 1 instead of the canonical
(a + 1) - 1. The following fixes this at least for commutative
tree codes. For comparisons which we also canonicalize in the
plumbing (by means of changing the comparison code via
swap_tree_comparison) this isn't that easily done. I'm thinking
of a proper solution here.
Bootstrap & regtest running on x86_64-unknown-linux-gnu.
Richard.
2015-07-03 Richard Biener <rguenther@suse.de>
* genmatch.c (commutative_tree_code, commutative_ternary_tree_code):
Copy from tree.c
(dt_operand::gen_gimple_expr): After valueizing operands
re-canonicalize operand order for commutative tree codes.
Index: gcc/genmatch.c
===================================================================
--- gcc/genmatch.c (revision 225368)
+++ gcc/genmatch.c (working copy)
@@ -175,6 +175,62 @@ END_BUILTINS
};
#undef DEF_BUILTIN
+/* Return true if CODE represents a commutative tree code. Otherwise
+ return false. */
+bool
+commutative_tree_code (enum tree_code code)
+{
+ switch (code)
+ {
+ case PLUS_EXPR:
+ case MULT_EXPR:
+ case MULT_HIGHPART_EXPR:
+ case MIN_EXPR:
+ case MAX_EXPR:
+ case BIT_IOR_EXPR:
+ case BIT_XOR_EXPR:
+ case BIT_AND_EXPR:
+ case NE_EXPR:
+ case EQ_EXPR:
+ case UNORDERED_EXPR:
+ case ORDERED_EXPR:
+ case UNEQ_EXPR:
+ case LTGT_EXPR:
+ case TRUTH_AND_EXPR:
+ case TRUTH_XOR_EXPR:
+ case TRUTH_OR_EXPR:
+ case WIDEN_MULT_EXPR:
+ case VEC_WIDEN_MULT_HI_EXPR:
+ case VEC_WIDEN_MULT_LO_EXPR:
+ case VEC_WIDEN_MULT_EVEN_EXPR:
+ case VEC_WIDEN_MULT_ODD_EXPR:
+ return true;
+
+ default:
+ break;
+ }
+ return false;
+}
+
+/* Return true if CODE represents a ternary tree code for which the
+ first two operands are commutative. Otherwise return false. */
+bool
+commutative_ternary_tree_code (enum tree_code code)
+{
+ switch (code)
+ {
+ case WIDEN_MULT_PLUS_EXPR:
+ case WIDEN_MULT_MINUS_EXPR:
+ case DOT_PROD_EXPR:
+ case FMA_EXPR:
+ return true;
+
+ default:
+ break;
+ }
+ return false;
+}
+
/* Base class for all identifiers the parser knows. */
@@ -1996,6 +2052,25 @@ dt_operand::gen_gimple_expr (FILE *f)
child_opname, child_opname);
fprintf (f, "{\n");
}
+ /* While the toplevel operands are canonicalized by the caller
+ after valueizing operands of sub-expressions we have to
+ re-canonicalize operand order. */
+ if (operator_id *code = dyn_cast <operator_id *> (id))
+ {
+ /* ??? We can't canonicalize tcc_comparison operands here
+ because that requires changing the comparison code which
+ we already matched... */
+ if (commutative_tree_code (code->code)
+ || commutative_ternary_tree_code (code->code))
+ {
+ char child_opname0[20], child_opname1[20];
+ gen_opname (child_opname0, 0);
+ gen_opname (child_opname1, 1);
+ fprintf (f, "if (tree_swap_operands_p (%s, %s, false))\n"
+ " std::swap (%s, %s);\n", child_opname0, child_opname1,
+ child_opname0, child_opname1);
+ }
+ }
return n_ops;
}
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