Hi,
This is an attempt to fix missed optimization: x+x+x+x -> 4*x as
reported in PR63586.
Regression tested and bootstrapped on x86-64-linux-gnu with no new
regressions.
Is this OK for next stage1?
Thanks,
Kugan
gcc/testsuite/ChangeLog:
2016-02-26 Kugan Vivekanandarajah <kug...@linaro.org>
PR middle-end/63586
* gcc.dg/tree-ssa/reassoc-14.c: Fix multiply count.
gcc/ChangeLog:
2016-02-26 Kugan Vivekanandarajah <kug...@linaro.org>
PR middle-end/63586
* tree-ssa-reassoc.c (transform_add_to_multiply): New.
(reassociate_bb): Call transform_add_to_multiply.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/reassoc-14.c
b/gcc/testsuite/gcc.dg/tree-ssa/reassoc-14.c
index 62802d1..16ebc86 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/reassoc-14.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/reassoc-14.c
@@ -19,6 +19,7 @@ unsigned int test2 (unsigned int x, unsigned int y, unsigned
int z,
return tmp1 + tmp2 + tmp3;
}
-/* There should be one multiplication left in test1 and three in test2. */
+/* There should be two multiplication left in test1 (inculding one generated
+ when converting addition to multiplication) and three in test2. */
-/* { dg-final { scan-tree-dump-times "\\\*" 4 "reassoc1" } } */
+/* { dg-final { scan-tree-dump-times "\\\*" 5 "reassoc1" } } */
diff --git a/gcc/tree-ssa-reassoc.c b/gcc/tree-ssa-reassoc.c
index dfd0da1..2454b9d 100644
--- a/gcc/tree-ssa-reassoc.c
+++ b/gcc/tree-ssa-reassoc.c
@@ -1698,6 +1698,61 @@ eliminate_redundant_comparison (enum tree_code opcode,
return false;
}
+/* Recursively transoform repeated addition of same values into multiply with
+ constant. */
+static void
+transform_add_to_multiply (gimple_stmt_iterator *gsi, gimple *stmt,
vec<operand_entry *> *ops)
+{
+ operand_entry *oe;
+ tree op = NULL_TREE;
+ int i, start = -1, end = 0, count = 0;
+
+ /* Look for repeated operands. */
+ FOR_EACH_VEC_ELT (*ops, i, oe)
+ {
+ if (start == -1)
+ {
+ count = 1;
+ op = oe->op;
+ start = i;
+ }
+ else if (operand_equal_p (oe->op, op, 0))
+ {
+ count++;
+ end = i;
+ }
+ else if (count == 1)
+ {
+ count = 1;
+ op = oe->op;
+ start = i;
+ }
+ else
+ break;
+ }
+
+ if (count > 1)
+ {
+ /* Convert repeated operand addition to multiplication. */
+ for (i = end; i >= start; --i)
+ ops->unordered_remove (i);
+ tree tmp = make_temp_ssa_name (TREE_TYPE (op), NULL, "reassocmul");
+ gassign *mul_stmt = gimple_build_assign (tmp, MULT_EXPR,
+ op, build_int_cst
(TREE_TYPE(op), count));
+ gimple_set_location (mul_stmt, gimple_location (stmt));
+ gimple_set_uid (mul_stmt, gimple_uid (stmt));
+ gsi_insert_before (gsi, mul_stmt, GSI_SAME_STMT);
+ oe = operand_entry_pool.allocate ();
+ oe->op = tmp;
+ oe->rank = get_rank (op) * count;
+ oe->id = 0;
+ oe->count = 1;
+ ops->safe_push (oe);
+ transform_add_to_multiply (gsi, stmt, ops);
+ }
+}
+
+
/* Perform various identities and other optimizations on the list of
operand entries, stored in OPS. The tree code for the binary
operation between all the operands is OPCODE. */
@@ -4854,6 +4909,12 @@ reassociate_bb (basic_block bb)
&& flag_unsafe_math_optimizations)
powi_result = attempt_builtin_powi (stmt, &ops);
+ if (rhs_code == PLUS_EXPR)
+ {
+ transform_add_to_multiply (&gsi, stmt, &ops);
+ ops.qsort (sort_by_operand_rank);
+ }
+
/* If the operand vector is now empty, all operands were
consumed by the __builtin_powi optimization. */
if (ops.length () == 0)