On Wed, Nov 01, 2017 at 02:49:45PM +0100, Eric Botcazou wrote:
> > At least, the only spot that used to mention df_link in compare-elim.c was:
> > struct df_link *ref_chain;
> > ref_chain = DF_REF_CHAIN (use);
> > if (!ref_chain || !ref_chain->ref
> >
> > || !DF_REF_INSN_INFO (ref_chain->ref) || ref_chain->next != NULL)
> >
> > return false;
> >
> > rtx_insn *def_insn = DF_REF_INSN (ref_chain->ref);
> > and
> > df_chain_add_problem (DF_UD_CHAIN + DF_DU_CHAIN);
> > that ensured it is computed, but the former is replaced with the patch by
> > rtx_insn *def_insn = cmp->in_a_setter;
> > which is computed during the bb walking using the last_setter array
> > and the latter is dropped.
>
> Then why does the patch not remove the df_chain_add_problem call itself?
Oops, I thought I've removed it, but apparently I haven't; thanks for
catching it. Here is an updated patch I'll bootstrap/regtest soon.
2017-11-01 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/82778
PR rtl-optimization/82597
* compare-elim.c (struct comparison): Add in_a_setter field.
(find_comparison_dom_walker::before_dom_children): Remove killed
bitmap and df_simulate_find_defs call, instead walk the defs.
Compute last_setter and initialize in_a_setter. Merge definitions
with first initialization for a few variables.
(try_validate_parallel): Use insn_invalid_p instead of
recog_memoized. Return insn rather than just the pattern.
(try_merge_compare): Fix up comment. Don't uselessly test if
in_a is a REG_P. Use cmp->in_a_setter instead of walking UD
chains.
(execute_compare_elim_after_reload): Remove df_chain_add_problem
call.
* g++.dg/opt/pr82778.C: New test.
2017-10-31 Michael Collison <michael.colli...@arm.com>
PR rtl-optimization/82597
* gcc.dg/pr82597.c: New test.
--- gcc/compare-elim.c.jj 2017-10-31 20:01:31.431670403 +0100
+++ gcc/compare-elim.c 2017-11-01 14:51:42.482884881 +0100
@@ -97,6 +97,9 @@ struct comparison
/* The insn prior to the comparison insn that clobbers the flags. */
rtx_insn *prev_clobber;
+ /* The insn prior to the comparison insn that sets in_a REG. */
+ rtx_insn *in_a_setter;
+
/* The two values being compared. These will be either REGs or
constants. */
rtx in_a, in_b;
@@ -309,26 +312,22 @@ can_eliminate_compare (rtx compare, rtx
edge
find_comparison_dom_walker::before_dom_children (basic_block bb)
{
- struct comparison *last_cmp;
- rtx_insn *insn, *next, *last_clobber;
- bool last_cmp_valid;
+ rtx_insn *insn, *next;
bool need_purge = false;
- bitmap killed;
-
- killed = BITMAP_ALLOC (NULL);
+ rtx_insn *last_setter[FIRST_PSEUDO_REGISTER];
/* The last comparison that was made. Will be reset to NULL
once the flags are clobbered. */
- last_cmp = NULL;
+ struct comparison *last_cmp = NULL;
/* True iff the last comparison has not been clobbered, nor
have its inputs. Used to eliminate duplicate compares. */
- last_cmp_valid = false;
+ bool last_cmp_valid = false;
/* The last insn that clobbered the flags, if that insn is of
a form that may be valid for eliminating a following compare.
To be reset to NULL once the flags are set otherwise. */
- last_clobber = NULL;
+ rtx_insn *last_clobber = NULL;
/* Propagate the last live comparison throughout the extended basic block. */
if (single_pred_p (bb))
@@ -338,6 +337,7 @@ find_comparison_dom_walker::before_dom_c
last_cmp_valid = last_cmp->inputs_valid;
}
+ memset (last_setter, 0, sizeof (last_setter));
for (insn = BB_HEAD (bb); insn; insn = next)
{
rtx src;
@@ -346,10 +346,6 @@ find_comparison_dom_walker::before_dom_c
if (!NONDEBUG_INSN_P (insn))
continue;
- /* Compute the set of registers modified by this instruction. */
- bitmap_clear (killed);
- df_simulate_find_defs (insn, killed);
-
src = conforming_compare (insn);
if (src)
{
@@ -373,6 +369,13 @@ find_comparison_dom_walker::before_dom_c
last_cmp->in_b = XEXP (src, 1);
last_cmp->eh_note = eh_note;
last_cmp->orig_mode = GET_MODE (src);
+ if (last_cmp->in_b == const0_rtx
+ && last_setter[REGNO (last_cmp->in_a)])
+ {
+ rtx set = single_set (last_setter[REGNO (last_cmp->in_a)]);
+ if (set && rtx_equal_p (SET_DEST (set), last_cmp->in_a))
+ last_cmp->in_a_setter = last_setter[REGNO (last_cmp->in_a)];
+ }
all_compares.safe_push (last_cmp);
/* It's unusual, but be prepared for comparison patterns that
@@ -388,28 +391,36 @@ find_comparison_dom_walker::before_dom_c
find_flags_uses_in_insn (last_cmp, insn);
/* Notice if this instruction kills the flags register. */
- if (bitmap_bit_p (killed, targetm.flags_regnum))
- {
- /* See if this insn could be the "clobber" that eliminates
- a future comparison. */
- last_clobber = (arithmetic_flags_clobber_p (insn) ? insn : NULL);
-
- /* In either case, the previous compare is no longer valid. */
- last_cmp = NULL;
- last_cmp_valid = false;
- }
+ df_ref def;
+ FOR_EACH_INSN_DEF (def, insn)
+ if (DF_REF_REGNO (def) == targetm.flags_regnum)
+ {
+ /* See if this insn could be the "clobber" that eliminates
+ a future comparison. */
+ last_clobber = (arithmetic_flags_clobber_p (insn)
+ ? insn : NULL);
+
+ /* In either case, the previous compare is no longer valid. */
+ last_cmp = NULL;
+ last_cmp_valid = false;
+ break;
+ }
}
- /* Notice if any of the inputs to the comparison have changed. */
- if (last_cmp_valid
- && (bitmap_bit_p (killed, REGNO (last_cmp->in_a))
- || (REG_P (last_cmp->in_b)
- && bitmap_bit_p (killed, REGNO (last_cmp->in_b)))))
- last_cmp_valid = false;
+ /* Notice if any of the inputs to the comparison have changed
+ and remember last insn that sets each register. */
+ df_ref def;
+ FOR_EACH_INSN_DEF (def, insn)
+ {
+ if (last_cmp_valid
+ && (DF_REF_REGNO (def) == REGNO (last_cmp->in_a)
+ || (REG_P (last_cmp->in_b)
+ && DF_REF_REGNO (def) == REGNO (last_cmp->in_b))))
+ last_cmp_valid = false;
+ last_setter[DF_REF_REGNO (def)] = insn;
+ }
}
- BITMAP_FREE (killed);
-
/* Remember the live comparison for subsequent members of
the extended basic block. */
if (last_cmp)
@@ -625,13 +636,19 @@ can_merge_compare_into_arith (rtx_insn *
static rtx
try_validate_parallel (rtx set_a, rtx set_b)
{
- rtx par
- = gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, set_a, set_b));
+ rtx par = gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, set_a, set_b));
+ rtx_insn *insn = make_insn_raw (par);
- rtx_insn *insn;
- insn = gen_rtx_INSN (VOIDmode, 0, 0, 0, par, 0, -1, 0);
+ if (insn_invalid_p (insn, false))
+ {
+ crtl->emit.x_cur_insn_uid--;
+ return NULL_RTX;
+ }
- return recog_memoized (insn) > 0 ? par : NULL_RTX;
+ SET_PREV_INSN (insn) = NULL_RTX;
+ SET_NEXT_INSN (insn) = NULL_RTX;
+ INSN_LOCATION (insn) = 0;
+ return insn;
}
/* For a comparison instruction described by CMP check if it compares a
@@ -643,7 +660,7 @@ try_validate_parallel (rtx set_a, rtx se
<instructions that don't read the condition register>
I2: CC := CMP R1 0
I2 can be merged with I1 into:
- I1: { R1 := R2 + R3 ; CC := CMP (R2 + R3) 0 }
+ I1: { CC := CMP (R2 + R3) 0 ; R1 := R2 + R3 }
This catches cases where R1 is used between I1 and I2 and therefore
combine and other RTL optimisations will not try to propagate it into
I2. Return true if we succeeded in merging CMP. */
@@ -653,7 +670,7 @@ try_merge_compare (struct comparison *cm
{
rtx_insn *cmp_insn = cmp->insn;
- if (!REG_P (cmp->in_a) || cmp->in_b != const0_rtx)
+ if (cmp->in_b != const0_rtx || cmp->in_a_setter == NULL)
return false;
rtx in_a = cmp->in_a;
df_ref use;
@@ -664,24 +681,8 @@ try_merge_compare (struct comparison *cm
if (!use)
return false;
- /* Validate the data flow information before attempting to
- find the instruction that defines in_a. */
-
- struct df_link *ref_chain;
- ref_chain = DF_REF_CHAIN (use);
- if (!ref_chain || !ref_chain->ref
- || !DF_REF_INSN_INFO (ref_chain->ref) || ref_chain->next != NULL)
- return false;
-
- rtx_insn *def_insn = DF_REF_INSN (ref_chain->ref);
- /* We found the insn that defines in_a. Only consider the cases where
- it is in the same block as the comparison. */
- if (BLOCK_FOR_INSN (cmp_insn) != BLOCK_FOR_INSN (def_insn))
- return false;
-
+ rtx_insn *def_insn = cmp->in_a_setter;
rtx set = single_set (def_insn);
- if (!set)
- return false;
if (!can_merge_compare_into_arith (cmp_insn, def_insn))
return false;
@@ -855,7 +856,6 @@ try_eliminate_compare (struct comparison
static unsigned int
execute_compare_elim_after_reload (void)
{
- df_chain_add_problem (DF_UD_CHAIN + DF_DU_CHAIN);
df_analyze ();
gcc_checking_assert (!all_compares.exists ());
--- gcc/testsuite/g++.dg/opt/pr82778.C.jj 2017-11-01 14:51:27.882064433
+0100
+++ gcc/testsuite/g++.dg/opt/pr82778.C 2017-11-01 14:51:27.882064433 +0100
@@ -0,0 +1,37 @@
+// PR rtl-optimization/82778
+// { dg-do compile }
+// { dg-options "-O2" }
+
+template <typename a, int b> struct c {
+ typedef a d[b];
+ static a e(d f, int g) { return f[g]; }
+};
+template <typename a, int b> struct B {
+ typedef c<a, b> h;
+ typename h::d i;
+ long j;
+ a at() { return h::e(i, j); }
+};
+int k, m, r, s, t;
+char l, n, q;
+short o, p, w;
+struct C {
+ int u;
+};
+B<C, 4> v;
+void x() {
+ if (((p > (q ? v.at().u : k)) >> l - 226) + !(n ^ r * m))
+ s = ((-(((p > (q ? v.at().u : k)) >> l - 226) + !(n ^ r * m)) < 0) /
+ (-(((p > (q ? v.at().u : k)) >> l - 226) + !(n ^ r * m)) ^
+ -25 & o) &&
+ p) >>
+ (0 <= 0
+ ? 0 ||
+ (-(((p > (q ? v.at().u : k)) >> l - 226) + !(n ^ r * m)) <
+ 0) /
+ (-(((p > (q ? v.at().u : k)) >> l - 226) +
+ !(n ^ r * m)) ^ -25 & o)
+ : 0);
+ w = (p > (q ? v.at().u : k)) >> l - 226;
+ t = !(n ^ r * m);
+}
--- gcc/testsuite/gcc.dg/pr82597.c.jj 2017-11-01 14:51:27.882064433 +0100
+++ gcc/testsuite/gcc.dg/pr82597.c 2017-11-01 14:51:27.882064433 +0100
@@ -0,0 +1,40 @@
+/* PR rtl-optimization/82597 */
+/* { dg-do compile }*/
+/* { dg-options "-O2 -funroll-loops" } */
+
+int pb;
+
+void
+ch (unsigned char np, char fc)
+{
+ unsigned char *y6 = &np;
+
+ if (fc != 0)
+ {
+ unsigned char *z1 = &np;
+
+ for (;;)
+ if (*y6 != 0)
+ for (fc = 0; fc < 12; ++fc)
+ {
+ int hh;
+ int tp;
+
+ if (fc != 0)
+ hh = (*z1 != 0) ? fc : 0;
+ else
+ hh = pb;
+
+ tp = fc > 0;
+ if (hh == tp)
+ *y6 = 1;
+ }
+ }
+
+ if (np != 0)
+ y6 = (unsigned char *)&fc;
+ if (pb != 0 && *y6 != 0)
+ for (;;)
+ {
+ }
+}
Jakub
