On 18 June 2014 05:32, Jeff Law <[email protected]> wrote:
> On 06/11/14 03:35, Zhenqiang Chen wrote:
>>
>>
>> Thanks for the comments. df_live seams redundant.
>>
>> With flag_ira_loop_pressure, the pass will call df_analyze () at the
>> beginning, which can make sure all the DF info are correct.
>>
>> Can we guarantee all DF_... correct without df_analyze ()?
>
> They should be fine in this context.
>
>
>
>> +/* Pre-check candidate DEST to skip the one which can not make a valid
>> insn
>> + during move_invariant_reg. SIMPlE is to skip HARD_REGISTER. */
>
> s/SIMPlE/SIMPLE/
>
>
>
>> + {
>> + /* Multi definitions at this stage, most likely are due to
>> + instruction constrain, which requires both read and
>> write
>
> s/constrain/constraints/
>
> Though that doesn't make sense. Constraints don't come into play until much
> later in the pipeline. Certainly there's been code in the expanders and
> elsewhere to try and make the code we generate more acceptable to 2-address
> targets and that's probably what you're really running into. I think the
> code is fine, but that you need to improve the comment.
>
> ISTM that if your primary focus is to filter out read/write operands, then
> just say that and ignore the constraints or other mechanisms by which we got
> a read/write pseudo.
>
> So I think with those two small comment changes, this patch is OK for the
> trunk. Please post the final version for archival purposes before checking
> it in.
Thanks. Patch was installed @r211885 with the two comment changes and
one more change to use
FOR_EACH_INSN_INFO_DEF
other than
for (def_rec = DF_INSN_INFO_DEFS (insn_info); *def_rec; def_rec++)
Bootstrap and no make check regression on X86-64.
Index: gcc/loop-invariant.c
===================================================================
--- gcc/loop-invariant.c (revision 211832)
+++ gcc/loop-invariant.c (working copy)
@@ -839,6 +839,39 @@
return true;
}
+/* Pre-check candidate DEST to skip the one which can not make a valid insn
+ during move_invariant_reg. SIMPLE is to skip HARD_REGISTER. */
+static bool
+pre_check_invariant_p (bool simple, rtx dest)
+{
+ if (simple && REG_P (dest) && DF_REG_DEF_COUNT (REGNO (dest)) > 1)
+ {
+ df_ref use;
+ rtx ref;
+ unsigned int i = REGNO (dest);
+ struct df_insn_info *insn_info;
+ df_ref def_rec;
+
+ for (use = DF_REG_USE_CHAIN (i); use; use = DF_REF_NEXT_REG (use))
+ {
+ ref = DF_REF_INSN (use);
+ insn_info = DF_INSN_INFO_GET (ref);
+
+ FOR_EACH_INSN_INFO_DEF (def_rec, insn_info)
+ if (DF_REF_REGNO (def_rec) == i)
+ {
+ /* Multi definitions at this stage, most likely are due to
+ instruction constraints, which requires both read and write
+ on the same register. Since move_invariant_reg is not
+ powerful enough to handle such cases, just ignore the INV
+ and leave the chance to others. */
+ return false;
+ }
+ }
+ }
+ return true;
+}
+
/* Finds invariant in INSN. ALWAYS_REACHED is true if the insn is always
executed. ALWAYS_EXECUTED is true if the insn is always executed,
unless the program ends due to a function call. */
@@ -868,7 +901,8 @@
|| HARD_REGISTER_P (dest))
simple = false;
- if (!may_assign_reg_p (SET_DEST (set))
+ if (!may_assign_reg_p (dest)
+ || !pre_check_invariant_p (simple, dest)
|| !check_maybe_invariant (SET_SRC (set)))
return;
