This patch abstracts out a couple common idioms in the forward
threader that I found useful while navigating the code base.
Tested on x86-64 Linux.
OK?
gcc/ChangeLog:
* tree-ssa-threadedge.c (has_phis_p): New.
(forwarder_block_p): New.
(potentially_threadable_block): Call forwarder_block_p.
(jump_threader::thread_around_empty_blocks): Call has_phis_p.
(jump_threader::thread_through_normal_block): Call
forwarder_block_p.
---
gcc/tree-ssa-threadedge.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)
diff --git a/gcc/tree-ssa-threadedge.c b/gcc/tree-ssa-threadedge.c
index e57f6d3e39c..3db54a199fd 100644
--- a/gcc/tree-ssa-threadedge.c
+++ b/gcc/tree-ssa-threadedge.c
@@ -95,6 +95,21 @@ jump_threader::thread_through_all_blocks (bool
may_peel_loop_headers)
return m_registry->thread_through_all_blocks (may_peel_loop_headers);
}
+static inline bool
+has_phis_p (basic_block bb)
+{
+ return !gsi_end_p (gsi_start_phis (bb));
+}
+
+/* Return TRUE for a forwarder block which is defined as having PHIs
+ but no instructions. */
+
+static bool
+forwarder_block_p (basic_block bb)
+{
+ return gsi_end_p (gsi_start_nondebug_bb (bb)) && has_phis_p (bb);
+}
+
/* Return TRUE if we may be able to thread an incoming edge into
BB to an outgoing edge from BB. Return FALSE otherwise. */
@@ -107,9 +122,8 @@ potentially_threadable_block (basic_block bb)
not optimized away because they forward from outside a loop
to the loop header. We want to thread through them as we can
sometimes thread to the loop exit, which is obviously profitable.
- the interesting case here is when the block has PHIs. */
- if (gsi_end_p (gsi_start_nondebug_bb (bb))
- && !gsi_end_p (gsi_start_phis (bb)))
+ The interesting case here is when the block has PHIs. */
+ if (forwarder_block_p (bb))
return true;
/* If BB has a single successor or a single predecessor, then
@@ -854,7 +868,7 @@ jump_threader::thread_around_empty_blocks
(vec<jump_thread_edge *> *path,
/* The key property of these blocks is that they need not be duplicated
when threading. Thus they cannot have visible side effects such
as PHI nodes. */
- if (!gsi_end_p (gsi_start_phis (bb)))
+ if (has_phis_p (bb))
return false;
/* Skip over DEBUG statements at the start of the block. */
@@ -994,8 +1008,7 @@ jump_threader::thread_through_normal_block
(vec<jump_thread_edge *> *path,
{
/* First case. The statement simply doesn't have any instructions, but
does have PHIs. */
- if (gsi_end_p (gsi_start_nondebug_bb (e->dest))
- && !gsi_end_p (gsi_start_phis (e->dest)))
+ if (forwarder_block_p (e->dest))
return 0;
/* Second case. */
--
2.31.1
