This avoids going back-and-forth from linearized to widened
expressions in reassoc twice and only rewrites expressions
according to reassoc-width in the last reassoc pass.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2019-06-25 Richard Biener <rguent...@suse.de>
PR tree-optimization/90930
* tree-ssa-reassoc.c (reassociate_bb): Only rewrite expression
into parallel form in the last pass instance.
* gcc.dg/tree-ssa/reassoc-24.c: Adjust.
* gcc.dg/tree-ssa/reassoc-25.c: Likewise.
Index: gcc/tree-ssa-reassoc.c
===================================================================
--- gcc/tree-ssa-reassoc.c (revision 272636)
+++ gcc/tree-ssa-reassoc.c (working copy)
@@ -6013,12 +6013,7 @@ reassociate_bb (basic_block bb)
{
machine_mode mode = TYPE_MODE (TREE_TYPE (lhs));
int ops_num = ops.length ();
- int width = get_reassociation_width (ops_num, rhs_code, mode);
-
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file,
- "Width = %d was chosen for reassociation\n",
width);
-
+ int width;
/* For binary bit operations, if there are at least 3
operands and the last last operand in OPS is a constant,
@@ -6032,10 +6027,21 @@ reassociate_bb (basic_block bb)
&& TREE_CODE (ops.last ()->op) == INTEGER_CST)
std::swap (*ops[0], *ops[ops_num - 1]);
- if (width > 1
- && ops.length () > 3)
- rewrite_expr_tree_parallel (as_a <gassign *> (stmt),
- width, ops);
+ /* Only rewrite the expression tree to parallel in the
+ last reassoc pass to avoid useless work back-and-forth
+ with initial linearization. */
+ if (!reassoc_insert_powi_p
+ && ops.length () > 3
+ && (width = get_reassociation_width (ops_num, rhs_code,
+ mode)) > 1)
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file,
+ "Width = %d was chosen for reassociation\n",
+ width);
+ rewrite_expr_tree_parallel (as_a <gassign *> (stmt),
+ width, ops);
+ }
else
{
/* When there are three operands left, we want
Index: gcc/testsuite/gcc.dg/tree-ssa/reassoc-24.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/reassoc-24.c (revision 272636)
+++ gcc/testsuite/gcc.dg/tree-ssa/reassoc-24.c (working copy)
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-O2 --param tree-reassoc-width=2 -fdump-tree-reassoc1" } */
+/* { dg-options "-O2 --param tree-reassoc-width=2 -fdump-tree-reassoc2" } */
unsigned int
foo (void)
@@ -21,4 +21,4 @@ foo (void)
/* Verify there are two pairs of __asm__ statements with no
intervening stmts. */
-/* { dg-final { scan-tree-dump-times "__asm__\[^;\n]*;\n *__asm__" 2
"reassoc1"} } */
+/* { dg-final { scan-tree-dump-times "__asm__\[^;\n]*;\n *__asm__" 2
"reassoc2"} } */
Index: gcc/testsuite/gcc.dg/tree-ssa/reassoc-25.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/reassoc-25.c (revision 272636)
+++ gcc/testsuite/gcc.dg/tree-ssa/reassoc-25.c (working copy)
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-O2 --param tree-reassoc-width=3
-fdump-tree-reassoc1-details" } */
+/* { dg-options "-O2 --param tree-reassoc-width=3
-fdump-tree-reassoc2-details" } */
unsigned int
foo (int a, int b, int c, int d)
@@ -15,4 +15,4 @@ foo (int a, int b, int c, int d)
}
/* Verify reassociation width was chosen to be 2. */
-/* { dg-final { scan-tree-dump-times "Width = 2" 1 "reassoc1"} } */
+/* { dg-final { scan-tree-dump-times "Width = 2" 1 "reassoc2"} } */
