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 <rguent...@suse.de>
PR ipa/68470
* ipa-split.c (split_function): Handle main part not returning.
* g++.dg/torture/pr68470.C: New testcase.
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();
+}
+
