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Re: [PATCH, PR43920, 9/9] Cross-jumping - Allow both directions.
- From: Tom de Vries <vries at codesourcery dot com>
- To: gcc-patches at gcc dot gnu dot org, ebotcazou at libertysurf dot fr
- Date: Fri, 01 Apr 2011 16:56:34 +0200
- Subject: Re: [PATCH, PR43920, 9/9] Cross-jumping - Allow both directions.
- References: <4D94C603.7080505@codesourcery.com> <4D94C88B.4020206@codesourcery.com> <4D94CBDD.9060304@codesourcery.com>
Reposting, with ChangeLog.
2011-04-01 Tom de Vries <tom@codesourcery.com>
PR target/43920
* cfgcleanup.c (try_crossjump_to_edge): Add dir parameter. Pass dir to
flow_find_cross_jump. Swap variables to implement backward replacement.
(try_crossjump_bb): Add argument to try_crossjump_to_edge.
diff -u gcc/cfgcleanup.c gcc/cfgcleanup.c
--- gcc/cfgcleanup.c (working copy)
+++ gcc/cfgcleanup.c (working copy)
@@ -69,7 +69,7 @@
information; we should run df_analyze to enable more opportunities. */
static bool block_was_dirty;
-static bool try_crossjump_to_edge (int, edge, edge);
+static bool try_crossjump_to_edge (int, edge, edge, enum replace_direction);
static bool try_crossjump_bb (int, basic_block);
static bool outgoing_edges_match (int, basic_block, basic_block);
static enum replace_direction old_insns_match_p (int, rtx, rtx);
@@ -1695,15 +1695,17 @@
/* E1 and E2 are edges with the same destination block. Search their
predecessors for common code. If found, redirect control flow from
- (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC. */
+ (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC (dir_forward),
+ or the other way around (dir_backward). DIR specifies the allowed
+ replacement direction. */
static bool
-try_crossjump_to_edge (int mode, edge e1, edge e2)
+try_crossjump_to_edge (int mode, edge e1, edge e2,
+ enum replace_direction dir)
{
int nmatch;
basic_block src1 = e1->src, src2 = e2->src;
basic_block redirect_to, redirect_from, to_remove;
basic_block osrc1, osrc2, redirect_edges_to, tmp;
- enum replace_direction dir;
rtx newpos1, newpos2;
edge s;
edge_iterator ei;
@@ -1757,8 +1759,7 @@
return false;
/* ... and part the second. */
- dir = dir_forward;
nmatch = flow_find_cross_jump (src1, src2, &newpos1, &newpos2, &dir);
osrc1 = src1;
osrc2 = src2;
@@ -1767,5 +1768,15 @@
if (newpos2 != NULL_RTX)
src2 = BLOCK_FOR_INSN (newpos2);
+ if (dir == dir_backward)
+ {
+#define SWAP(T, X, Y) do { T tmp = (X); (X) = (Y); (Y) = tmp; } while (0)
+ SWAP (basic_block, osrc1, osrc2);
+ SWAP (basic_block, src1, src2);
+ SWAP (edge, e1, e2);
+ SWAP (rtx, newpos1, newpos2);
+#undef SWAP
+ }
+
/* Don't proceed with the crossjump unless we found a sufficient number
of matching instructions or the 'from' block was totally matched
@@ -2020,7 +2031,7 @@
|| (fallthru->src->flags & BB_MODIFIED)))
continue;
- if (try_crossjump_to_edge (mode, e, fallthru))
+ if (try_crossjump_to_edge (mode, e, fallthru, dir_forward))
{
changed = true;
ix = 0;
@@ -2068,7 +2079,9 @@
|| (e2->src->flags & BB_MODIFIED)))
continue;
- if (try_crossjump_to_edge (mode, e, e2))
+ /* Both e and e2 are not fallthru edges, so we can crossjump in either
+ direction. */
+ if (try_crossjump_to_edge (mode, e, e2, dir_both))
{
changed = true;
ix = 0;