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Re: [PATCH] Factor out gimple_dont_merge_p


On 11-11-13 10:37, Richard Biener wrote:
On Sat, 9 Nov 2013, Tom de Vries wrote:

Richard,

This patch factors out gimple_dont_merge_p from gimple_equal_p and
find_duplicate.

Bootstrapped and regtested on x86_64.

OK for trunk?

+static bool
+gimple_dont_merge_p (gimple stmt)
+{
+  switch (gimple_code (stmt))
+    {
+    case GIMPLE_CALL:
+      /* Eventually, we'll significantly complicate the CFG by adding
+        back edges to properly model the effects of transaction restart.
+        For the bulk of optimization this does not matter, but what we
+        cannot recover from is tail merging blocks between two separate
+        transactions.  Avoid that by making commit not match.  */
+      if (gimple_call_builtin_p (stmt, BUILT_IN_TM_COMMIT))
+       return true;
+
+      /* We cannot tail-merge the builtins that end transactions.
+        ??? The alternative being unsharing of BBs in the tm_init pass.
*/
+      if (flag_tm
+         && (gimple_call_flags (stmt) & ECF_TM_BUILTIN)
+         && is_tm_ending_fndecl (gimple_call_fndecl (stmt)))
+       return true;


1) BUILT_IN_TM_COMMIT is handled in is_tm_ending_fndecl,
2) fndecl may be NULL

I'd simply get rid of gimple_dont_merge_p and call a
is_tm_ending (gimple) function you'd add to TM.


Richard,

I've update the patch according to comments, bootstrapped and reg-tested.

OK for trunk?

Thanks,
- Tom

2013-11-06  Tom de Vries  <tom@codesourcery.com>

	* trans-mem.c (is_tm_ending): New function.
	* gimple.h (is_tm_ending): Declare.
	* tree-ssa-tail-merge.c (gimple_equal_p): Remove test on
	BUILT_IN_TM_COMMIT.
	(find_duplicate): Use is_tm_ending instead of is_tm_ending_fndecl.

diff --git a/gcc/gimple.h b/gcc/gimple.h
index 33e790c..8f902b9 100644
--- a/gcc/gimple.h
+++ b/gcc/gimple.h
@@ -1043,6 +1043,7 @@ extern bool infer_nonnull_range (gimple, tree);
 /* In trans-mem.c.  */
 extern void diagnose_tm_safe_errors (tree);
 extern void compute_transaction_bits (void);
+extern bool is_tm_ending (gimple);
 
 /* In tree-nested.c.  */
 extern void lower_nested_functions (tree);
diff --git a/gcc/trans-mem.c b/gcc/trans-mem.c
index 784ff24..7dca40e 100644
--- a/gcc/trans-mem.c
+++ b/gcc/trans-mem.c
@@ -321,6 +321,22 @@ is_tm_ending_fndecl (tree fndecl)
   return false;
 }
 
+/* Return true if STMT is a built in function call that "ends" a
+   transaction.  */
+
+bool
+is_tm_ending (gimple stmt)
+{
+  tree fndecl;
+
+  if (gimple_code (stmt) != GIMPLE_CALL)
+    return false;
+
+  fndecl = gimple_call_fndecl (stmt);
+  return (fndecl != NULL_TREE
+	  && is_tm_ending_fndecl (fndecl));
+}
+
 /* Return true if STMT is a TM load.  */
 
 static bool
diff --git a/gcc/tree-ssa-tail-merge.c b/gcc/tree-ssa-tail-merge.c
index 00dd071..15356bd 100644
--- a/gcc/tree-ssa-tail-merge.c
+++ b/gcc/tree-ssa-tail-merge.c
@@ -1099,14 +1099,6 @@ gimple_equal_p (same_succ same_succ, gimple s1, gimple s2)
       if (!gimple_call_same_target_p (s1, s2))
         return false;
 
-      /* Eventually, we'll significantly complicate the CFG by adding
-	 back edges to properly model the effects of transaction restart.
-	 For the bulk of optimization this does not matter, but what we
-	 cannot recover from is tail merging blocks between two separate
-	 transactions.  Avoid that by making commit not match.  */
-      if (gimple_call_builtin_p (s1, BUILT_IN_TM_COMMIT))
-	return false;
-
       for (i = 0; i < gimple_call_num_args (s1); ++i)
 	{
 	  t1 = gimple_call_arg (s1, i);
@@ -1220,15 +1212,14 @@ find_duplicate (same_succ same_succ, basic_block bb1, basic_block bb2)
       gimple stmt1 = gsi_stmt (gsi1);
       gimple stmt2 = gsi_stmt (gsi2);
 
-      if (!gimple_equal_p (same_succ, stmt1, stmt2))
+      /* What could be better than to this this here is to blacklist the bb
+	 containing the stmt, when encountering the stmt f.i. in
+	 same_succ_hash.  */
+      if (is_tm_ending (stmt1)
+	  || is_tm_ending (stmt2))
 	return;
 
-      // We cannot tail-merge the builtins that end transactions.
-      // ??? The alternative being unsharing of BBs in the tm_init pass.
-      if (flag_tm
-	  && is_gimple_call (stmt1)
-	  && (gimple_call_flags (stmt1) & ECF_TM_BUILTIN)
-	  && is_tm_ending_fndecl (gimple_call_fndecl (stmt1)))
+      if (!gimple_equal_p (same_succ, stmt1, stmt2))
 	return;
 
       gsi_prev_nondebug (&gsi1);

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