On 14-08-14 16:34, Richard Biener wrote:
On Sat, Aug 9, 2014 at 7:14 AM, Tom de Vries <tom_devr...@mentor.com> wrote:
On 08-08-14 17:17, Tom de Vries wrote:
Maybe instead of a new mem_alias_equal_p simply compare MEM_ATTRs
with mem_attrs_eq_p?
I propose to fix it this way (as attached) on 4.8/4.9/trunk, and maybe do
a more
efficient handling on trunk as a follow-up patch.
I'll put this through bootstrap/test again.
Bootstrapped and reg-tested on trunk x86_64.
Re-attached patch OK for trunk, 4.8, 4.9 ?
Ok.
Backported to 4.8 and 4.9 as attached.
The emit-rtl.{c,h} part of my patch was superfluous on trunk given that you
already exported mem_attrs_eq_p, something I failed to notice when rebasing. So
the backport contains that part of your patch. I've tested the backport patch on
4.9.
(did you check the effect on code-generation? that is, how many
opportunities compiling GCC do we "lose"?)
I haven't done that. I can look into that (after I fix the tail-merge part of
pr62004).
Thanks,
- Tom
2014-08-15 Tom de Vries <t...@codesourcery.com>
Backport from mainline:
2014-08-14 Tom de Vries <t...@codesourcery.com>
PR rtl-optimization/62004
PR rtl-optimization/62030
* ifcvt.c (rtx_interchangeable_p): New function.
(noce_try_move, noce_process_if_block): Use rtx_interchangeable_p.
* gcc.dg/pr62004.c: New test.
* gcc.dg/pr62030.c: Same.
* gcc.target/mips/pr62030-octeon.c: Same.
2014-08-05 Richard Biener <rguent...@suse.de>
* emit-rtl.h (mem_attrs_eq_p): Declare.
* emit-rtl.c (mem_attrs_eq_p): Export.
diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 4736f8d..89b6768 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -245,7 +245,7 @@ const_fixed_htab_eq (const void *x, const void *y)
/* Return true if the given memory attributes are equal. */
-static bool
+bool
mem_attrs_eq_p (const struct mem_attrs *p, const struct mem_attrs *q)
{
return (p->alias == q->alias
diff --git a/gcc/emit-rtl.h b/gcc/emit-rtl.h
index fe68de9..36eb0c8 100644
--- a/gcc/emit-rtl.h
+++ b/gcc/emit-rtl.h
@@ -20,6 +20,9 @@ along with GCC; see the file COPYING3. If not see
#ifndef GCC_EMIT_RTL_H
#define GCC_EMIT_RTL_H
+/* Return whether two MEM_ATTRs are equal. */
+bool mem_attrs_eq_p (const struct mem_attrs *, const struct mem_attrs *);
+
/* Set the alias set of MEM to SET. */
extern void set_mem_alias_set (rtx, alias_set_type);
diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c
index 0d1adce..49ff85c 100644
--- a/gcc/ifcvt.c
+++ b/gcc/ifcvt.c
@@ -306,6 +306,28 @@ block_fallthru (basic_block bb)
return (e) ? e->dest : NULL_BLOCK;
}
+
+/* Return true if RTXs A and B can be safely interchanged. */
+
+static bool
+rtx_interchangeable_p (const_rtx a, const_rtx b)
+{
+ if (!rtx_equal_p (a, b))
+ return false;
+
+ if (GET_CODE (a) != MEM)
+ return true;
+
+ /* A dead type-unsafe memory reference is legal, but a live type-unsafe memory
+ reference is not. Interchanging a dead type-unsafe memory reference with
+ a live type-safe one creates a live type-unsafe memory reference, in other
+ words, it makes the program illegal.
+ We check here conservatively whether the two memory references have equal
+ memory attributes. */
+
+ return mem_attrs_eq_p (get_mem_attrs (a), get_mem_attrs (b));
+}
+
/* Go through a bunch of insns, converting them to conditional
execution format if possible. Return TRUE if all of the non-note
@@ -1034,6 +1056,9 @@ noce_try_move (struct noce_if_info *if_info)
|| (rtx_equal_p (if_info->a, XEXP (cond, 1))
&& rtx_equal_p (if_info->b, XEXP (cond, 0))))
{
+ if (!rtx_interchangeable_p (if_info->a, if_info->b))
+ return FALSE;
+
y = (code == EQ) ? if_info->a : if_info->b;
/* Avoid generating the move if the source is the destination. */
@@ -2504,7 +2529,7 @@ noce_process_if_block (struct noce_if_info *if_info)
if (! insn_b
|| insn_b != last_active_insn (else_bb, FALSE)
|| (set_b = single_set (insn_b)) == NULL_RTX
- || ! rtx_equal_p (x, SET_DEST (set_b)))
+ || ! rtx_interchangeable_p (x, SET_DEST (set_b)))
return FALSE;
}
else
@@ -2517,7 +2542,7 @@ noce_process_if_block (struct noce_if_info *if_info)
|| BLOCK_FOR_INSN (insn_b) != BLOCK_FOR_INSN (if_info->cond_earliest)
|| !NONJUMP_INSN_P (insn_b)
|| (set_b = single_set (insn_b)) == NULL_RTX
- || ! rtx_equal_p (x, SET_DEST (set_b))
+ || ! rtx_interchangeable_p (x, SET_DEST (set_b))
|| ! noce_operand_ok (SET_SRC (set_b))
|| reg_overlap_mentioned_p (x, SET_SRC (set_b))
|| modified_between_p (SET_SRC (set_b), insn_b, jump)
@@ -2583,7 +2608,7 @@ noce_process_if_block (struct noce_if_info *if_info)
/* Look and see if A and B are really the same. Avoid creating silly
cmove constructs that no one will fix up later. */
- if (rtx_equal_p (a, b))
+ if (rtx_interchangeable_p (a, b))
{
/* If we have an INSN_B, we don't have to create any new rtl. Just
move the instruction that we already have. If we don't have an
diff --git a/gcc/testsuite/gcc.dg/pr62004.c b/gcc/testsuite/gcc.dg/pr62004.c
new file mode 100644
index 0000000..c994a41
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr62004.c
@@ -0,0 +1,47 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -fno-tree-tail-merge" } */
+
+struct node
+{
+ struct node *next;
+ struct node *prev;
+};
+
+struct node node;
+
+struct head
+{
+ struct node *first;
+};
+
+struct head heads[5];
+
+int k = 2;
+
+struct head *head = &heads[2];
+
+int
+main ()
+{
+ struct node *p;
+
+ node.next = (void*)0;
+
+ node.prev = (void *)head;
+
+ head->first = &node;
+
+ struct node *n = head->first;
+
+ struct head *h = &heads[k];
+
+ heads[2].first = n->next;
+
+ if ((void*)n->prev == (void *)h)
+ p = h->first;
+ else
+ /* Dead tbaa-unsafe load from ((struct node *)&heads[2])->next. */
+ p = n->prev->next;
+
+ return !(p == (void*)0);
+}
diff --git a/gcc/testsuite/gcc.dg/pr62030.c b/gcc/testsuite/gcc.dg/pr62030.c
new file mode 100644
index 0000000..b8baf93
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr62030.c
@@ -0,0 +1,50 @@
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+extern void abort (void);
+
+struct node
+{
+ struct node *next;
+ struct node *prev;
+};
+
+struct node node;
+
+struct head
+{
+ struct node *first;
+};
+
+struct head heads[5];
+
+int k = 2;
+
+struct head *head = &heads[2];
+
+static int __attribute__((noinline))
+foo (void)
+{
+ node.prev = (void *)head;
+ head->first = &node;
+
+ struct node *n = head->first;
+ struct head *h = &heads[k];
+ struct node *next = n->next;
+
+ if (n->prev == (void *)h)
+ h->first = next;
+ else
+ n->prev->next = next;
+
+ n->next = h->first;
+ return n->next == &node;
+}
+
+int
+main (void)
+{
+ if (foo ())
+ abort ();
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.target/mips/pr62030-octeon.c b/gcc/testsuite/gcc.target/mips/pr62030-octeon.c
new file mode 100644
index 0000000..5e3d3b3
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/pr62030-octeon.c
@@ -0,0 +1,50 @@
+/* { dg-do run } */
+/* { dg-options "-march=octeon" } */
+
+extern void abort (void);
+
+struct node
+{
+ struct node *next;
+ struct node *prev;
+};
+
+struct node node;
+
+struct head
+{
+ struct node *first;
+};
+
+struct head heads[5];
+
+int k = 2;
+
+struct head *head = &heads[2];
+
+static int __attribute__((noinline))
+foo (void)
+{
+ node.prev = (void *)head;
+ head->first = &node;
+
+ struct node *n = head->first;
+ struct head *h = &heads[k];
+ struct node *next = n->next;
+
+ if (n->prev == (void *)h)
+ h->first = next;
+ else
+ n->prev->next = next;
+
+ n->next = h->first;
+ return n->next == &node;
+}
+
+int
+main (void)
+{
+ if (foo ())
+ abort ();
+ return 0;
+}
--
1.9.1
