[gcc r12-5811] ranger: Add shortcuts for single-successor blocks

[gcc r12-5811] ranger: Add shortcuts for single-successor blocks

[Richard Sandiford]

https://gcc.gnu.org/g:63c59f054a5cd6d356ad8bce79182ab205b7aa43

commit r12-5811-g63c59f054a5cd6d356ad8bce79182ab205b7aa43
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Mon Dec 6 18:29:31 2021 +0000

    ranger: Add shortcuts for single-successor blocks
    
    When compiling an optabs.ii at -O2 with a release-checking build,
    there were 6,643,575 calls to gimple_outgoing_range_stmt_p.  96.8% of
    them were for blocks with a single successor, which never have a control
    statement that generates new range info.  This patch therefore adds a
    shortcut for that case.
    
    This gives a ~1% compile-time improvement for the test.
    
    I tried making the function inline (in the header) so that the
    single_succ_p didn't need to be repeated, but it seemed to make things
    slightly worse.
    
    gcc/
            * gimple-range-edge.cc (gimple_outgoing_range::edge_range_p): Add
            a shortcut for blocks with single successors.
            * gimple-range-gori.cc (gori_map::calculate_gori): Likewise.

Diff:
---
 gcc/gimple-range-edge.cc | 3 +++
 gcc/gimple-range-gori.cc | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/gcc/gimple-range-edge.cc b/gcc/gimple-range-edge.cc
index afffc8dbcae..9e805230004 100644
--- a/gcc/gimple-range-edge.cc
+++ b/gcc/gimple-range-edge.cc
@@ -182,6 +182,9 @@ gimple_outgoing_range::calc_switch_ranges (gswitch *sw)
 gimple *
 gimple_outgoing_range::edge_range_p (irange &r, edge e)
 {
+  if (single_succ_p (e->src))
+    return NULL;
+
   // Determine if there is an outgoing edge.
   gimple *s = gimple_outgoing_range_stmt_p (e->src);
   if (!s)
diff --git a/gcc/gimple-range-gori.cc b/gcc/gimple-range-gori.cc
index 6c17267ad37..8691abab443 100644
--- a/gcc/gimple-range-gori.cc
+++ b/gcc/gimple-range-gori.cc
@@ -555,6 +555,9 @@ gori_map::calculate_gori (basic_block bb)
   m_outgoing[bb->index] = BITMAP_ALLOC (&m_bitmaps);
   m_incoming[bb->index] = BITMAP_ALLOC (&m_bitmaps);
 
+  if (single_succ_p (bb))
+    return;
+
   // If this block's last statement may generate range informaiton, go
   // calculate it.
   gimple *stmt = gimple_outgoing_range_stmt_p (bb);