[trans-mem] rewrite irrevocability propagation with CFG

[Aldy Hernandez <aldyh at redhat dot com>]

Hey there.

This patch fixes the propagation of the irrevocability bit to use the
CFG instead of a dominator walk.  

Downward propagation is still done with immediate dominators to catch
cases like the testcases below in which we've propagated irrevocability
to the top of the transaction, but need to push it back down to rest of
the blocks below.  Eeech, that explanation was horrible, I can draw
pretty graphs if I'm being nonsensical.

The testcases below exhibit cases which we previously got wrong.

OK for branch?

BTW, with this patch we've cleaned everything dealing with dominators.

	* trans-mem.c: Include langhooks.h.
	(get_tm_region_blocks): Remove region parameter.  Add exit_blocks
	and irr_blocks parameters.  Adjust accordingly.
	(execute_tm_mark): Adjust calls to get_tm_region_blocks.
	(execute_tm_edges): Same.
	(execute_tm_memopt): Same.
	(ipa_tm_diagnose_transaction): Same.
	(ipa_tm_propagate_irr): Rewrite to walk CFG instead of dominator
	tree.  Remove parent_irr parameter.
	(ipa_tm_scan_irr_function): Adjust call to ipa_tm_propagate_irr.
	Dump irrevocable blocks.
	* Makefile.in (trans-mem.o): Depend on langhooks.h.

Index: testsuite/gcc.dg/tm/irrevocable-5.c
===================================================================
--- testsuite/gcc.dg/tm/irrevocable-5.c	(revision 0)
+++ testsuite/gcc.dg/tm/irrevocable-5.c	(revision 0)
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-fgnu-tm -fdump-ipa-tmipa -O" } */
+
+int a;
+
+void foo(void) __attribute__((transaction_safe));
+void bar(void) __attribute__((transaction_safe));
+void danger(void) __attribute__((transaction_unsafe));
+
+void wildthing()
+{
+  /* All blocks should be propagated as irrevocable.  */
+  __transaction [[relaxed]] {
+    if (a)
+      foo();
+    else
+      bar();
+    danger();
+  }
+}
+
+/* { dg-final { scan-ipa-dump-times "GTMA_DOES_GO_IRREVOCABLE" 1 "tmipa" } } */
+/* { dg-final { scan-ipa-dump-times "bb 3 goes irr" 1 "tmipa" } } */
+/* { dg-final { scan-ipa-dump-times "bb 4 goes irr" 1 "tmipa" } } */
+/* { dg-final { scan-ipa-dump-times "bb 5 goes irr" 1 "tmipa" } } */
+/* { dg-final { scan-ipa-dump-times "bb 6 goes irr" 1 "tmipa" } } */
+/* { dg-final { cleanup-ipa-dump "tmipa" } } */
Index: testsuite/gcc.dg/tm/irrevocable-6.c
===================================================================
--- testsuite/gcc.dg/tm/irrevocable-6.c	(revision 0)
+++ testsuite/gcc.dg/tm/irrevocable-6.c	(revision 0)
@@ -0,0 +1,34 @@
+/* { dg-do compile } */
+/* { dg-options "-fgnu-tm -fdump-ipa-tmipa -O" } */
+
+int a, trxn, eee;
+
+void foo(void) __attribute__((transaction_safe));
+void bar(void) __attribute__((transaction_safe));
+void danger(void) __attribute__((transaction_unsafe));
+
+void wildthing()
+{
+  /* All blocks should be propagated as irrevocable.  */
+  __transaction [[relaxed]] {
+    if (eee) {
+      if (a)
+	foo();
+      else
+	bar();
+      danger();
+    } else {
+      danger();
+    }
+  }
+}
+
+/* { dg-final { scan-ipa-dump-times "GTMA_DOES_GO_IRREVOCABLE" 1 "tmipa" } } */
+/* { dg-final { scan-ipa-dump-times "bb 3 goes irr" 1 "tmipa" } } */
+/* { dg-final { scan-ipa-dump-times "bb 4 goes irr" 1 "tmipa" } } */
+/* { dg-final { scan-ipa-dump-times "bb 5 goes irr" 1 "tmipa" } } */
+/* { dg-final { scan-ipa-dump-times "bb 6 goes irr" 1 "tmipa" } } */
+/* { dg-final { scan-ipa-dump-times "bb 7 goes irr" 1 "tmipa" } } */
+/* { dg-final { scan-ipa-dump-times "bb 8 goes irr" 1 "tmipa" } } */
+/* { dg-final { scan-ipa-dump-times "bb 9 goes irr" 1 "tmipa" } } */
+/* { dg-final { cleanup-ipa-dump "tmipa" } } */
Index: trans-mem.c
===================================================================
--- trans-mem.c	(revision 156478)
+++ trans-mem.c	(working copy)
@@ -37,6 +37,7 @@
 #include "ggc.h"
 #include "params.h"
 #include "target.h"
+#include "langhooks.h"
 
 
 #define PROB_VERY_UNLIKELY	(REG_BR_PROB_BASE / 2000 - 1)
@@ -2097,7 +2098,10 @@ expand_block_tm (struct tm_region *regio
    following a TM_IRREVOCABLE call.  */
 
 static VEC (basic_block, heap) *
-get_tm_region_blocks (struct tm_region *region, bool stop_at_irrevocable_p)
+get_tm_region_blocks (basic_block entry_block,
+		      bitmap exit_blocks,
+		      bitmap irr_blocks,
+		      bool stop_at_irrevocable_p)
 {
   VEC(basic_block, heap) *bbs = NULL;
   unsigned i;
@@ -2106,26 +2110,28 @@ get_tm_region_blocks (struct tm_region *
   bitmap visited_blocks = BITMAP_ALLOC (NULL);
 
   i = 0;
-  VEC_safe_push (basic_block, heap, bbs, region->entry_block);
+  VEC_safe_push (basic_block, heap, bbs, entry_block);
+  bitmap_set_bit (visited_blocks, entry_block->index);
 
   do
     {
       basic_block bb = VEC_index (basic_block, bbs, i++);
 
-      bitmap_set_bit (visited_blocks, bb->index);
-
-      if (region->exit_blocks &&
-	  bitmap_bit_p (region->exit_blocks, bb->index))
+      if (exit_blocks &&
+	  bitmap_bit_p (exit_blocks, bb->index))
 	continue;
 
       if (stop_at_irrevocable_p
-	  && region->irr_blocks
-	  && bitmap_bit_p (region->irr_blocks, bb->index))
+	  && irr_blocks
+	  && bitmap_bit_p (irr_blocks, bb->index))
 	continue;
 
       FOR_EACH_EDGE (e, ei, bb->succs)
 	if (!bitmap_bit_p (visited_blocks, e->dest->index))
-	  VEC_safe_push (basic_block, heap, bbs, e->dest);
+	  {
+	    bitmap_set_bit (visited_blocks, e->dest->index);
+	    VEC_safe_push (basic_block, heap, bbs, e->dest);
+	  }
     }
   while (i < VEC_length (basic_block, bbs));
 
@@ -2164,7 +2170,10 @@ execute_tm_mark (void)
 	    subcode &= GTMA_DECLARATION_MASK;
 	  gimple_transaction_set_subcode (region->transaction_stmt, subcode);
 
-	  queue = get_tm_region_blocks (region, /*stop_at_irr_p=*/true);
+	  queue = get_tm_region_blocks (region->entry_block,
+					region->exit_blocks,
+					region->irr_blocks,
+					/*stop_at_irr_p=*/true);
 	  for (i = 0; VEC_iterate (basic_block, queue, i, bb); ++i)
 	    expand_block_tm (region, bb);
 	  VEC_free (basic_block, heap, queue);
@@ -2396,7 +2405,10 @@ execute_tm_edges (void)
 	/* Collect the set of blocks in this region.  Do this before
 	   splitting edges, so that we don't have to play with the
 	   dominator tree in the middle.  */
-	queue = get_tm_region_blocks (region, /*stop_at_irr_p=*/false);
+	queue = get_tm_region_blocks (region->entry_block,
+				      region->exit_blocks,
+				      region->irr_blocks,
+				      /*stop_at_irr_p=*/false);
 	expand_transaction (region);
 	for (i = 0; VEC_iterate (basic_block, queue, i, bb); ++i)
 	  expand_block_edges (region, bb);
@@ -3038,7 +3050,9 @@ execute_tm_memopt (void)
       bitmap_obstack_initialize (&tm_memopt_obstack);
 
       /* Save all BBs for the current region.  */
-      bbs = get_tm_region_blocks (region, false);
+      bbs = get_tm_region_blocks (region->entry_block,
+				  region->exit_blocks,
+				  region->irr_blocks, false);
 
       /* Collect all the memory operations.  */
       for (i = 0; VEC_iterate (basic_block, bbs, i, bb); ++i)
@@ -3395,48 +3409,52 @@ ipa_tm_scan_irr_blocks (VEC (basic_block
    tree which has been fully propagated; NEW_IRR is the set of new blocks
    which are gaining the irrevocable property during the current scan.  */
 
-static bool
-ipa_tm_propagate_irr (basic_block bb, bitmap new_irr, bitmap old_irr,
-		      bitmap exit_blocks, bool parent_irr)
+static void
+ipa_tm_propagate_irr (basic_block entry_block, bitmap new_irr, bitmap old_irr,
+		      bitmap exit_blocks)
 {
-  bool this_irr;
-  unsigned index = bb->index;
+  VEC (basic_block, heap) *bbs;
 
   /* If this block is in the old set, no need to rescan.  */
-  if (old_irr && bitmap_bit_p (old_irr, index))
-    return true;
-
-  /* For downward propagation, the block is irrevocable if either 
-     the parent block is irrevocable or a scan of the the block
-     revealed an irrevocable statement.  */
-  this_irr = (parent_irr || bitmap_bit_p (new_irr, index));
+  if (old_irr && bitmap_bit_p (old_irr, entry_block->index))
+    return;
 
-  if (!bitmap_bit_p (exit_blocks, index))
+  bbs = get_tm_region_blocks (entry_block, exit_blocks, NULL, false);
+  do
     {
-      basic_block son = first_dom_son (CDI_DOMINATORS, bb);
+      basic_block bb = VEC_pop (basic_block, bbs);
+      bool this_irr = bitmap_bit_p (new_irr, bb->index);
       bool all_son_irr = true;
+      edge_iterator ei;
+      edge e;
 
-      if (son)
+      /* Propagate up.  If my children are, I am too.  */
+      if (!this_irr)
 	{
-	  do
-	    {
-	      if (!ipa_tm_propagate_irr (son, new_irr, old_irr,
-					 exit_blocks, this_irr))
+	  FOR_EACH_EDGE (e, ei, bb->succs)
+	    if (!bitmap_bit_p (new_irr, e->dest->index))
+	      {
 		all_son_irr = false;
-	      son = next_dom_son (CDI_DOMINATORS, son);
+		break;
+	      }
+	  if (all_son_irr)
+	    {
+	      bitmap_set_bit (new_irr, bb->index);
+	      this_irr = true;
 	    }
-	  while (son);
+	}
 
-	  /* For upward propagation, the block is irrevocable if
-	     all dominated blocks are irrevocable.  */
-	  this_irr |= all_son_irr;
+      /* Propagate down to everyone we immediately dominate.  */
+      if (this_irr)
+	{
+	  basic_block son;
+	  for (son = first_dom_son (CDI_DOMINATORS, bb);
+	       son;
+	       son = next_dom_son (CDI_DOMINATORS, son))
+	    bitmap_set_bit (new_irr, son->index);
 	}
     }
-
-  if (this_irr)
-    bitmap_set_bit (new_irr, index);
-
-  return this_irr;
+  while (!VEC_empty (basic_block, bbs));
 }
 
 static void
@@ -3499,8 +3517,11 @@ ipa_tm_scan_irr_function (struct cgraph_
       old_irr = d->irrevocable_blocks_clone;
       VEC_quick_push (basic_block, queue, single_succ (ENTRY_BLOCK_PTR));
       if (ipa_tm_scan_irr_blocks (&queue, new_irr, old_irr, NULL))
-	ret = ipa_tm_propagate_irr (single_succ (ENTRY_BLOCK_PTR), new_irr,
-				    old_irr, NULL, false);
+	{
+	  ipa_tm_propagate_irr (single_succ (ENTRY_BLOCK_PTR), new_irr,
+				old_irr, NULL);
+	  ret = bitmap_bit_p (new_irr, single_succ (ENTRY_BLOCK_PTR)->index);
+	}
     }
   else
     {
@@ -3513,7 +3534,7 @@ ipa_tm_scan_irr_function (struct cgraph_
 	  if (ipa_tm_scan_irr_blocks (&queue, new_irr, old_irr,
 				      region->exit_blocks))
 	    ipa_tm_propagate_irr (region->entry_block, new_irr, old_irr,
-				  region->exit_blocks, false);
+				  region->exit_blocks);
 	}
     }
 
@@ -3541,6 +3562,17 @@ ipa_tm_scan_irr_function (struct cgraph_
   else
     BITMAP_FREE (new_irr);
 
+  if (dump_file)
+    {
+      const char *dname;
+      bitmap_iterator bmi;
+      unsigned i;
+
+      dname = lang_hooks.decl_printable_name (current_function_decl, 2);
+      EXECUTE_IF_SET_IN_BITMAP (new_irr, 0, i, bmi)
+	fprintf (dump_file, "%s: bb %d goes irrevocable\n", dname, i);
+    }
+
   VEC_free (basic_block, heap, queue);
   pop_cfun ();
   current_function_decl = NULL;
@@ -3631,11 +3663,14 @@ ipa_tm_diagnose_transaction (struct cgra
       }
     else
       {
-	VEC (basic_block, heap) *bbs = get_tm_region_blocks (r, false);
+	VEC (basic_block, heap) *bbs;
 	gimple_stmt_iterator gsi;
 	basic_block bb;
 	size_t i;
 
+	bbs = get_tm_region_blocks (r->entry_block, r->exit_blocks,
+				    r->irr_blocks, false);
+
 	for (i = 0; VEC_iterate (basic_block, bbs, i, bb); ++i)
 	  for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 	    {
Index: Makefile.in
===================================================================
--- Makefile.in	(revision 154874)
+++ Makefile.in	(working copy)
@@ -2167,7 +2167,7 @@ gtype-desc.o: gtype-desc.c $(CONFIG_H) $
 trans-mem.o : trans-mem.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
 	$(TREE_H) $(GIMPLE_H) $(TREE_FLOW_H) tree-pass.h except.h \
 	$(DIAGNOSTIC_H) $(TOPLEV_H) $(FLAGS_H) $(DEMANGLE_H) $(TRANS_MEM_H) \
-	$(TREE_DUMP_H) $(PARAMS_H)
+	$(TREE_DUMP_H) $(PARAMS_H) langhooks.h
 
 ggc-common.o: ggc-common.c $(CONFIG_H) $(SYSTEM_H) coretypes.h		\
 	$(GGC_H) $(HASHTAB_H) $(TOPLEV_H) $(PARAMS_H) hosthooks.h	\