On Mon, Nov 19, 2012 at 08:56:22AM -0800, Richard Henderson wrote:
> On 2012-11-18 23:53, Jakub Jelinek wrote:
> > I'd prefer to only invalidate the stack pointer on the first assignment
> > to the hard pointer. If the cselib link between sp and hfp is already
> > broken, invalidating sp will only result in worse code. Dunno if there
> > are any targets that adjust the hard frame pointer after it has been set
> > once or similar.
>
> I'm not aware of such a target. Though I did not audit them now.
>
> > Perhaps we could walk here CSELIB_VAL_PTR (hfpval)->locs here, and look
> > if any rtls in there have find_base_term (x->loc) == find_base_term
> > (stack_pointer_rtx), and only if yes, invalidate (and guard it by the
> > modified_in_p test).
>
> Sounds plausible.
>
> > BTW, var-tracking.c uses a similar test.
>
> Ouch. Where is that?
Here is an updated patch, bootstrapped/regtested on x86_64-linux and
i686-linux, ok for trunk?
2012-11-19 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/54921
* cselib.h (fp_setter_insn): New prototype.
* cselib.c (fp_setter_insn): New function.
(cselib_process_insn): If frame_pointer_needed,
call cselib_invalidate_rtx (stack_pointer_rtx) after
processing a frame pointer setter.
* var-tracking.c (fp_setter): Removed.
(vt_initialize): Use fp_setter_insn instead of fp_setter.
* gcc.dg/pr54921.c: New test.
--- gcc/cselib.h.jj 2012-10-16 13:20:25.000000000 +0200
+++ gcc/cselib.h 2012-11-19 19:02:27.768645544 +0100
@@ -78,6 +78,7 @@ extern void cselib_init (int);
extern void cselib_clear_table (void);
extern void cselib_finish (void);
extern void cselib_process_insn (rtx);
+extern bool fp_setter_insn (rtx);
extern enum machine_mode cselib_reg_set_mode (const_rtx);
extern int rtx_equal_for_cselib_p (rtx, rtx);
extern int references_value_p (const_rtx, int);
--- gcc/cselib.c.jj 2012-11-12 11:23:02.579098220 +0100
+++ gcc/cselib.c 2012-11-19 19:16:25.406747280 +0100
@@ -2593,6 +2593,28 @@ cselib_record_sets (rtx insn)
}
}
+/* Return true if INSN in the prologue initializes hard_frame_pointer_rtx. */
+
+bool
+fp_setter_insn (rtx insn)
+{
+ rtx expr, pat = NULL_RTX;
+
+ if (!RTX_FRAME_RELATED_P (insn))
+ return false;
+
+ expr = find_reg_note (insn, REG_FRAME_RELATED_EXPR, NULL_RTX);
+ if (expr)
+ pat = XEXP (expr, 0);
+ if (!modified_in_p (hard_frame_pointer_rtx, pat ? pat : insn))
+ return false;
+
+ /* Don't return true for frame pointer restores in the epilogue. */
+ if (find_reg_note (insn, REG_CFA_RESTORE, hard_frame_pointer_rtx))
+ return false;
+ return true;
+}
+
/* Record the effects of INSN. */
void
@@ -2651,6 +2673,15 @@ cselib_process_insn (rtx insn)
if (GET_CODE (XEXP (x, 0)) == CLOBBER)
cselib_invalidate_rtx (XEXP (XEXP (x, 0), 0));
+ /* On setter of the hard frame pointer if frame_pointer_needed,
+ invalidate stack_pointer_rtx, so that sp and {,h}fp based
+ VALUEs are distinct. */
+ if (reload_completed
+ && frame_pointer_needed
+ && RTX_FRAME_RELATED_P (insn)
+ && fp_setter_insn (insn))
+ cselib_invalidate_rtx (stack_pointer_rtx);
+
cselib_current_insn = NULL_RTX;
if (n_useless_values > MAX_USELESS_VALUES
--- gcc/var-tracking.c.jj 2012-11-19 14:41:26.000000000 +0100
+++ gcc/var-tracking.c 2012-11-19 18:59:13.638780830 +0100
@@ -9522,40 +9522,6 @@ vt_add_function_parameters (void)
}
}
-/* Return true if INSN in the prologue initializes hard_frame_pointer_rtx. */
-
-static bool
-fp_setter (rtx insn)
-{
- rtx pat = PATTERN (insn);
- if (RTX_FRAME_RELATED_P (insn))
- {
- rtx expr = find_reg_note (insn, REG_FRAME_RELATED_EXPR, NULL_RTX);
- if (expr)
- pat = XEXP (expr, 0);
- }
- if (GET_CODE (pat) == SET)
- {
- if (SET_DEST (pat) != hard_frame_pointer_rtx)
- return false;
- }
- else if (GET_CODE (pat) == PARALLEL)
- {
- int i;
- for (i = XVECLEN (pat, 0) - 1; i >= 0; i--)
- if (GET_CODE (XVECEXP (pat, 0, i)) == SET
- && SET_DEST (XVECEXP (pat, 0, i)) == hard_frame_pointer_rtx)
- break;
- if (i < 0)
- return false;
- }
- else
- return false;
- if (find_reg_note (insn, REG_CFA_RESTORE, hard_frame_pointer_rtx))
- return false;
- return true;
-}
-
/* Initialize cfa_base_rtx, create a preserved VALUE for it and
ensure it isn't flushed during cselib_reset_table.
Can be called only if frame_pointer_rtx resp. arg_pointer_rtx
@@ -9860,7 +9826,7 @@ vt_initialize (void)
if (fp_cfa_offset != -1
&& hard_frame_pointer_adjustment == -1
&& RTX_FRAME_RELATED_P (insn)
- && fp_setter (insn))
+ && fp_setter_insn (insn))
{
vt_init_cfa_base ();
hard_frame_pointer_adjustment = fp_cfa_offset;
--- gcc/testsuite/gcc.dg/pr54921.c.jj 2012-11-19 18:52:50.016031798 +0100
+++ gcc/testsuite/gcc.dg/pr54921.c 2012-11-19 18:52:50.016031798 +0100
@@ -0,0 +1,32 @@
+/* PR rtl-optimization/54921 */
+/* { dg-do run } */
+/* { dg-options "-Os -fno-omit-frame-pointer -fsched2-use-superblocks
-ftree-slp-vectorize" } */
+/* { dg-additional-options "-fstack-protector" { target fstack_protector } } */
+
+struct A
+{
+ int a;
+ char b[32];
+} a, b;
+
+__attribute__((noinline, noclone))
+struct A
+bar (int x)
+{
+ struct A r;
+ static int n;
+ r.a = ++n;
+ __builtin_memset (r.b, 0, sizeof (r.b));
+ r.b[0] = x;
+ return r;
+}
+
+int
+main ()
+{
+ a = bar (3);
+ b = bar (4);
+ if (a.a != 1 || a.b[0] != 3 || b.a != 2 || b.b[0] != 4)
+ __builtin_abort ();
+ return 0;
+}
Jakub
