On Tue, Jun 28, 2016 at 12:09:51PM +0200, Uros Bizjak wrote:
> > So, this patch instead changes ix86_expand_vector_move, so that
> > for SUBREGs it forces the SUBREG_REG into memory (or register if
> > that fails, though I don't have a testcase for when that would happen),
> > and just re-creates a SUBREG on the forced MEM (for whole size
> > SUBREGs that is in the end just using different mode for the MEM).
>
> There can be issue with paradoxical subregs, since subreg mode can be
> wider than original mode.
For paradoxical subregs, the extra bits are undefined, whether it is SUBREG
of a constant, REG or MEM, isn't that the case? Though I guess with MEM
there is a risk that reading the undefined bits from mem will be beyond end
of the data segment. It would really surprise me if something created a
paradoxical SUBREG of a CONSTANT_P.
Anyway, I can just always force_reg in that case, like:
2016-06-28 Jakub Jelinek <ja...@redhat.com>
PR middle-end/71626
* config/i386/i386.c (ix86_expand_vector_move): For SUBREG of
a constant, force its SUBREG_REG into memory or register instead
of whole op1.
* gcc.c-torture/execute/pr71626-1.c: New test.
* gcc.c-torture/execute/pr71626-2.c: New test.
--- gcc/config/i386/i386.c.jj 2016-06-27 14:50:51.000000000 +0200
+++ gcc/config/i386/i386.c 2016-06-28 10:51:18.444624190 +0200
@@ -19610,12 +19610,30 @@ ix86_expand_vector_move (machine_mode mo
of the register, once we have that information we may be able
to handle some of them more efficiently. */
if (can_create_pseudo_p ()
- && register_operand (op0, mode)
&& (CONSTANT_P (op1)
|| (SUBREG_P (op1)
&& CONSTANT_P (SUBREG_REG (op1))))
- && !standard_sse_constant_p (op1, mode))
- op1 = validize_mem (force_const_mem (mode, op1));
+ && ((register_operand (op0, mode)
+ && !standard_sse_constant_p (op1, mode))
+ /* ix86_expand_vector_move_misalign() does not like constants. */
+ || (SSE_REG_MODE_P (mode)
+ && MEM_P (op0)
+ && MEM_ALIGN (op0) < align)))
+ {
+ if (SUBREG_P (op1))
+ {
+ machine_mode imode = GET_MODE (SUBREG_REG (op1));
+ rtx r = (paradoxical_subreg_p (op1)
+ ? NULL_RTX : force_const_mem (imode, SUBREG_REG (op1)));
+ if (r)
+ r = validize_mem (r);
+ else
+ r = force_reg (imode, SUBREG_REG (op1));
+ op1 = simplify_gen_subreg (mode, r, imode, SUBREG_BYTE (op1));
+ }
+ else
+ op1 = validize_mem (force_const_mem (mode, op1));
+ }
/* We need to check memory alignment for SSE mode since attribute
can make operands unaligned. */
@@ -19626,13 +19643,8 @@ ix86_expand_vector_move (machine_mode mo
{
rtx tmp[2];
- /* ix86_expand_vector_move_misalign() does not like constants ... */
- if (CONSTANT_P (op1)
- || (SUBREG_P (op1)
- && CONSTANT_P (SUBREG_REG (op1))))
- op1 = validize_mem (force_const_mem (mode, op1));
-
- /* ... nor both arguments in memory. */
+ /* ix86_expand_vector_move_misalign() does not like both
+ arguments in memory. */
if (!register_operand (op0, mode)
&& !register_operand (op1, mode))
op1 = force_reg (mode, op1);
--- gcc/testsuite/gcc.c-torture/execute/pr71626-1.c.jj 2016-06-28
10:40:12.928186649 +0200
+++ gcc/testsuite/gcc.c-torture/execute/pr71626-1.c 2016-06-28
10:40:12.928186649 +0200
@@ -0,0 +1,19 @@
+/* PR middle-end/71626 */
+
+typedef __INTPTR_TYPE__ V __attribute__((__vector_size__(sizeof
(__INTPTR_TYPE__))));
+
+__attribute__((noinline, noclone)) V
+foo ()
+{
+ V v = { (__INTPTR_TYPE__) foo };
+ return v;
+}
+
+int
+main ()
+{
+ V v = foo ();
+ if (v[0] != (__INTPTR_TYPE__) foo)
+ __builtin_abort ();
+ return 0;
+}
--- gcc/testsuite/gcc.c-torture/execute/pr71626-2.c.jj 2016-06-28
10:40:12.928186649 +0200
+++ gcc/testsuite/gcc.c-torture/execute/pr71626-2.c 2016-06-28
10:40:12.928186649 +0200
@@ -0,0 +1,4 @@
+/* PR middle-end/71626 */
+/* { dg-additional-options "-fpic" { target fpic } } */
+
+#include "pr71626-1.c"
Jakub
