[COMMITTED] Make back_threader_registry inherit from back_jt_path_registry.

[COMMITTED] Make back_threader_registry inherit from back_jt_path_registry.

[Aldy Hernandez]

When a class's only purpose is to expose the methods of its only
member, it's really a derived class ;-).

Tested on x86-64 Linux.

Committed as obvious.

gcc/ChangeLog:

	* tree-ssa-threadbackward.c (class back_threader_registry):
	Inherit from back_jt_path_registry.
	(back_threader_registry::thread_through_all_blocks): Remove.
	(back_threader_registry::register_path): Remove
	m_lowlevel_registry prefix.
---
 gcc/tree-ssa-threadbackward.c | 21 +++++----------------
 1 file changed, 5 insertions(+), 16 deletions(-)

diff --git a/gcc/tree-ssa-threadbackward.c b/gcc/tree-ssa-threadbackward.c
index d9ce056b06c..6c1b15904ce 100644
--- a/gcc/tree-ssa-threadbackward.c
+++ b/gcc/tree-ssa-threadbackward.c
@@ -49,13 +49,10 @@ along with GCC; see the file COPYING3.  If not see
 // registered with register_path(), thread_through_all_blocks() is called
 // to modify the CFG.
 
-class back_threader_registry
+class back_threader_registry : public back_jt_path_registry
 {
 public:
   bool register_path (const vec<basic_block> &, edge taken);
-  bool thread_through_all_blocks (bool may_peel_loop_headers);
-private:
-  back_jt_path_registry m_lowlevel_registry;
 };
 
 // Class to abstract the profitability code for the backwards threader.
@@ -541,12 +538,6 @@ back_threader::debug ()
   dump (stderr);
 }
 
-bool
-back_threader_registry::thread_through_all_blocks (bool may_peel_loop_headers)
-{
-  return m_lowlevel_registry.thread_through_all_blocks (may_peel_loop_headers);
-}
-
 /* Examine jump threading path PATH and return TRUE if it is profitable to
    thread it, otherwise return FALSE.
 
@@ -873,8 +864,7 @@ bool
 back_threader_registry::register_path (const vec<basic_block> &m_path,
 				       edge taken_edge)
 {
-  vec<jump_thread_edge *> *jump_thread_path
-    = m_lowlevel_registry.allocate_thread_path ();
+  vec<jump_thread_edge *> *jump_thread_path = allocate_thread_path ();
 
   // The generic copier ignores the edge type.  We can build the
   // thread edges with any type.
@@ -885,12 +875,11 @@ back_threader_registry::register_path (const vec<basic_block> &m_path,
 
       edge e = find_edge (bb1, bb2);
       gcc_assert (e);
-      m_lowlevel_registry.push_edge (jump_thread_path, e, EDGE_COPY_SRC_BLOCK);
+      push_edge (jump_thread_path, e, EDGE_COPY_SRC_BLOCK);
     }
 
-  m_lowlevel_registry.push_edge (jump_thread_path,
-				 taken_edge, EDGE_NO_COPY_SRC_BLOCK);
-  m_lowlevel_registry.register_jump_thread (jump_thread_path);
+  push_edge (jump_thread_path, taken_edge, EDGE_NO_COPY_SRC_BLOCK);
+  register_jump_thread (jump_thread_path);
   return true;
 }
 
-- 
2.31.1

[COMMITTED] Improve backward threading with switches.

[Aldy Hernandez]

We've been essentially using find_taken_edge_switch_expr() in the
backward threader, but this is suboptimal because said function only
works with singletons.  VRP has a much smarter find_case_label_range
that works with ranges.

Tested on x86-64 Linux with:

	a) Bootstrap & regtests.

	b) Verifying we get more threads than before.

	c) Asserting that the new code catches everything the old one
	code caught (over a set of bootstrap .ii files).

Committed as obvious.

gcc/ChangeLog:

	* tree-ssa-threadbackward.c
	(back_threader::find_taken_edge_switch): Use find_case_label_range
	instead of find_taken_edge.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/vrp106.c: Adjust for threading.
	* gcc.dg/tree-ssa/vrp113.c: Same.
---
 gcc/testsuite/gcc.dg/tree-ssa/vrp106.c | 4 ++--
 gcc/testsuite/gcc.dg/tree-ssa/vrp113.c | 2 --
 gcc/tree-ssa-threadbackward.c          | 8 ++++----
 3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp106.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp106.c
index f25ea9c3826..dc5021a57b5 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/vrp106.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp106.c
@@ -1,6 +1,6 @@
 /* PR tree-optimization/18046  */
-/* { dg-options "-O2 -fdump-tree-vrp-thread1-details" }  */
-/* { dg-final { scan-tree-dump-times "Threaded jump" 1 "vrp-thread1" } }  */
+/* { dg-options "-O2 -fdump-tree-ethread-details" }  */
+/* { dg-final { scan-tree-dump-times "Registering jump thread" 1 "ethread" } }  */
 /* During VRP we expect to thread the true arm of the conditional through the switch
    and to the BB that corresponds to the 7 ... 9 case label.  */
 extern void foo (void);
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp113.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp113.c
index ab8d91e0f10..dfe4989d313 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/vrp113.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp113.c
@@ -13,5 +13,3 @@ int f(int a) {
       case 7: return 19;
     }
 }
-
-/* { dg-final { scan-tree-dump "return 3;" "vrp1" { xfail *-*-* } } } */
diff --git a/gcc/tree-ssa-threadbackward.c b/gcc/tree-ssa-threadbackward.c
index 6c1b15904ce..456effca5e1 100644
--- a/gcc/tree-ssa-threadbackward.c
+++ b/gcc/tree-ssa-threadbackward.c
@@ -195,11 +195,11 @@ back_threader::find_taken_edge_switch (const vec<basic_block> &path,
   if (r.varying_p ())
     return NULL;
 
-  tree val;
-  if (r.singleton_p (&val))
-    return ::find_taken_edge (gimple_bb (sw), val);
+  tree label = find_case_label_range (sw, &r);
+  if (!label)
+    return NULL;
 
-  return NULL;
+  return find_edge (gimple_bb (sw), label_to_block (cfun, CASE_LABEL (label)));
 }
 
 // Same as find_taken_edge, but for paths ending in a GIMPLE_COND.
-- 
2.31.1