diff mbox

Fix PR68470, ICE in IPA split

Message ID alpine.LSU.2.11.1511271209020.4884@t29.fhfr.qr
State New
Headers show

Commit Message

Richard Biener Nov. 27, 2015, 11:10 a.m. UTC 
On Fri, 27 Nov 2015, Richard Biener wrote:

> 
> This fixes the case where we split the returning part of a function
> and keep the non-returning part as main.  We were keeping the return
> block with stmts not relevant to main in the return path of the
> split which obviously doesn't work as it may use SSA names no longer
> defined (but split out).
> 
> The following patch detects the situation and pretends the exit
> block was found as EXIT_BLOCK_FOR_FN in this case.
> 
> Bootstrap and regtest ongoing on x86_64-unknown-linux-gnu.
> 
> Honza, does this look ok?

Ok, fails for example

FAIL: gcc.dg/vect/pr51581-1.c execution test

where we split a region at a point the main part falls thru to
(an odd place to split...).  Happens when we split at a loop
header but the pre-header remains in the main part.

Adjusted patch as follows.

Richard.

2015-11-27  Richard Biener  <rguenther@suse.de>

	PR ipa/68470
	* ipa-split.c (split_function): Handle main part not returning.

	* g++.dg/torture/pr68470.C: New testcase.
diff mbox

Patch

Index: gcc/ipa-split.c
===================================================================
--- gcc/ipa-split.c	(revision 230998)
+++ gcc/ipa-split.c	(working copy)
@@ -1205,7 +1205,6 @@  split_function (basic_block return_bb, s
   edge e;
   edge_iterator ei;
   tree retval = NULL, real_retval = NULL, retbnd = NULL;
-  bool split_part_return_p = false;
   bool with_bounds = chkp_function_instrumented_p (current_function_decl);
   gimple *last_stmt = NULL;
   unsigned int i;
@@ -1246,12 +1245,28 @@  split_function (basic_block return_bb, s
 	args_to_pass.safe_push (arg);
       }
 
-  /* See if the split function will return.  */
+  /* See if the split function or the main part will return.  */
+  bool main_part_return_p = false;
+  bool split_part_return_p = false;
   FOR_EACH_EDGE (e, ei, return_bb->preds)
-    if (bitmap_bit_p (split_point->split_bbs, e->src->index))
-      break;
-  if (e)
-    split_part_return_p = true;
+    {
+      if (bitmap_bit_p (split_point->split_bbs, e->src->index))
+	split_part_return_p = true;
+      else
+	main_part_return_p = true;
+    }
+  /* The main part also returns if we we split on a fallthru edge
+     and the split part returns.  */
+  if (split_part_return_p)
+    FOR_EACH_EDGE (e, ei, split_point->entry_bb->preds)
+      {
+	if (! bitmap_bit_p (split_point->split_bbs, e->src->index)
+	    && single_succ_p (e->src))
+	  {
+	    main_part_return_p = true;
+	    break;
+	  }
+      }
 
   /* Add return block to what will become the split function.
      We do not return; no return block is needed.  */
@@ -1295,6 +1310,11 @@  split_function (basic_block return_bb, s
   else
     bitmap_set_bit (split_point->split_bbs, return_bb->index);
 
+  /* If the main part doesn't return pretend the return block wasn't
+     found for all of the following.  */
+  if (! main_part_return_p)
+    return_bb = EXIT_BLOCK_PTR_FOR_FN (cfun);
+
   /* If RETURN_BB has virtual operand PHIs, they must be removed and the
      virtual operand marked for renaming as we change the CFG in a way that
      tree-inline is not able to compensate for.
Index: gcc/testsuite/g++.dg/torture/pr68470.C
===================================================================
--- gcc/testsuite/g++.dg/torture/pr68470.C	(revision 0)
+++ gcc/testsuite/g++.dg/torture/pr68470.C	(working copy)
@@ -0,0 +1,36 @@ 
+/* { dg-do compile } */
+
+void deallocate(void *);
+void *a;
+
+struct C {
+    virtual void m_fn1();
+};
+
+struct D {
+    C *m_fn2() {
+	if (a)
+	  __builtin_abort();
+    }
+};
+D getd();
+
+struct vec_int {
+    int _M_start;
+    ~vec_int() {
+	if (_M_start)
+	  deallocate(&_M_start);
+    }
+};
+vec_int *b;
+
+struct I {
+    virtual void m_fn3();
+};
+
+void I::m_fn3() {
+    if (a)
+      getd().m_fn2()->m_fn1();
+    b->~vec_int();
+}
+