Re: [PATCH 1/2] Allow REG_EQUAL for ZERO_EXTRACT

[Kugan <kugan dot vivekanandarajah at linaro dot org>]

On 30/06/15 17:16, Maxim Kuvyrkov wrote:
>> On Jun 30, 2015, at 6:54 AM, Kugan <kugan.vivekanandarajah@linaro.org> wrote:
>>
>>
>> On 29/06/15 21:56, Maxim Kuvyrkov wrote:
>>>> On Jun 28, 2015, at 2:28 PM, Kugan <kugan.vivekanandarajah@linaro.org> wrote:
>>>>
>>>> This patch allows setting REG_EQUAL for ZERO_EXTRACT and handle that in
>>>> cse (where the src for the ZERO_EXTRACT needs to be calculated)
>>>>
>>>> Thanks,
>>>> Kugan
>>>
>>>> From 75e746e559ffd21b25542b3db627e3b318118569 Mon Sep 17 00:00:00 2001
>>>> From: Kugan Vivekanandarajah <kugan.vivekanandarajah@linaro.org>
>>>> Date: Fri, 26 Jun 2015 17:12:07 +1000
>>>> Subject: [PATCH 1/2] Allow adding REG_EQUAL for ZERO_EXTRACT
>>>>
>>>> ---
>>>> gcc/ChangeLog  |  6 ++++++
>>>> gcc/cse.c      | 41 ++++++++++++++++++++++++++++++++++++++++-
>>>> gcc/emit-rtl.c |  3 ++-
>>>> 3 files changed, 48 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/gcc/ChangeLog b/gcc/ChangeLog
>>>> index 080aa39..d4a73d6 100644
>>>> --- a/gcc/ChangeLog
>>>> +++ b/gcc/ChangeLog
>>>> @@ -1,3 +1,9 @@
>>>> +2015-06-26  Kugan Vivekanandarajah  <kuganv@linaro.org>
>>>> +
>>>> +	* cse.c (cse_insn): Calculate src_eqv for ZERO_EXTRACT.
>>>> +	* emit-rtl.c (set_for_reg_notes): Allow ZERO_EXTRACT to set
>>>> +	REG_EQUAL note.
>>>> +
>>>> 2015-06-25  H.J. Lu  <hongjiu.lu@intel.com>
>>>>
>>>> 	* gentarget-def.c (def_target_insn): Cast return of strtol to
>>>> diff --git a/gcc/cse.c b/gcc/cse.c
>>>> index 100c9c8..8add651 100644
>>>> --- a/gcc/cse.c
>>>> +++ b/gcc/cse.c
>>>> @@ -4531,8 +4531,47 @@ cse_insn (rtx_insn *insn)
>>>>   if (n_sets == 1 && REG_NOTES (insn) != 0
>>>>       && (tem = find_reg_note (insn, REG_EQUAL, NULL_RTX)) != 0
>>>>       && (! rtx_equal_p (XEXP (tem, 0), SET_SRC (sets[0].rtl))
>>>> +	  || GET_CODE (SET_DEST (sets[0].rtl)) == ZERO_EXTRACT
>>>> 	  || GET_CODE (SET_DEST (sets[0].rtl)) == STRICT_LOW_PART))
>>>> -    src_eqv = copy_rtx (XEXP (tem, 0));
>>>> +    {
>>>> +      src_eqv = copy_rtx (XEXP (tem, 0));
>>>> +
>>>> +      /* If DEST is of the form ZERO_EXTACT, as in:
>>>> +	 (set (zero_extract:SI (reg:SI 119)
>>>> +		  (const_int 16 [0x10])
>>>> +		  (const_int 16 [0x10]))
>>>> +	      (const_int 51154 [0xc7d2]))
>>>> +	 REG_EQUAL note will specify the value of register (reg:SI 119) at this
>>>> +	 point.  Note that this is different from SRC_EQV. We can however
>>>> +	 calculate SRC_EQV with the position and width of ZERO_EXTRACT.  */
>>>> +      if (GET_CODE (SET_DEST (sets[0].rtl)) == ZERO_EXTRACT)
>>>
>>> Consider changing
>>>
>>> if (something
>>>    && (!rtx_equal_p)
>>>        || ZERO_EXTRACT
>>>        || STRICT_LOW_PART)
>>>
>>> to 
>>>
>>> if (something
>>>    && !rtx_equal_p)
>>>  {
>>>     if (ZERO_EXTRACT)
>>>       {
>>>       }
>>>     else if (STRICT_LOW_PART)
>>>       {
>>>       }
>>>  }
>>>
>>> Otherwise looks good to me, but you still need another approval.
>>
>> Thanks Maxim for the review. How about the attached patch?
> 
> Looks good, with a couple of indentation nit-picks below.  No need to repost the patch on their account.  Wait for another a maintainer's review.

Thanks. Here is the update patch.

Kugan

>From 0b86c1ed630ef70e17412808d6baca93259de2ee Mon Sep 17 00:00:00 2001
From: Kugan Vivekanandarajah <kugan.vivekanandarajah@linaro.org>
Date: Fri, 26 Jun 2015 17:12:07 +1000
Subject: [PATCH 1/3] Allow adding REG_EQUAL for ZERO_EXTRACT

---
 gcc/ChangeLog  |  7 +++++++
 gcc/cse.c      | 49 ++++++++++++++++++++++++++++++++++++++++++-------
 gcc/emit-rtl.c |  3 ++-
 3 files changed, 51 insertions(+), 8 deletions(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fc23abd..5796f16 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+
+2015-06-26  Kugan Vivekanandarajah  <kuganv@linaro.org>
+
+	* cse.c (cse_insn): Calculate src_eqv for ZERO_EXTRACT.
+	* emit-rtl.c (set_for_reg_notes): Allow ZERO_EXTRACT to set
+	REG_EQUAL note.
+
 2015-06-30  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* lto-streamer-out.c (class DFS): Adjust hash_scc method.
diff --git a/gcc/cse.c b/gcc/cse.c
index e01240c..09dc7c2 100644
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -4525,14 +4525,49 @@ cse_insn (rtx_insn *insn)
   canonicalize_insn (insn, &sets, n_sets);
 
   /* If this insn has a REG_EQUAL note, store the equivalent value in SRC_EQV,
-     if different, or if the DEST is a STRICT_LOW_PART.  The latter condition
-     is necessary because SRC_EQV is handled specially for this case, and if
-     it isn't set, then there will be no equivalence for the destination.  */
+     if different, or if the DEST is a STRICT_LOW_PART/ZERO_EXTRACT.  The
+     latter condition is necessary because SRC_EQV is handled specially for
+     this case, and if it isn't set, then there will be no equivalence
+     for the destination.  */
   if (n_sets == 1 && REG_NOTES (insn) != 0
-      && (tem = find_reg_note (insn, REG_EQUAL, NULL_RTX)) != 0
-      && (! rtx_equal_p (XEXP (tem, 0), SET_SRC (sets[0].rtl))
-	  || GET_CODE (SET_DEST (sets[0].rtl)) == STRICT_LOW_PART))
-    src_eqv = copy_rtx (XEXP (tem, 0));
+      && (tem = find_reg_note (insn, REG_EQUAL, NULL_RTX)) != 0)
+    {
+      if ((! rtx_equal_p (XEXP (tem, 0), SET_SRC (sets[0].rtl)))
+	  || GET_CODE (SET_DEST (sets[0].rtl)) == STRICT_LOW_PART)
+	src_eqv = copy_rtx (XEXP (tem, 0));
+
+      /* If DEST is of the form ZERO_EXTACT, as in:
+	 (set (zero_extract:SI (reg:SI 119)
+		  (const_int 16 [0x10])
+		  (const_int 16 [0x10]))
+	      (const_int 51154 [0xc7d2]))
+	 REG_EQUAL note will specify the value of register (reg:SI 119) at this
+	 point.  Note that this is different from SRC_EQV. We can however
+	 calculate SRC_EQV with the position and width of ZERO_EXTRACT.  */
+      else if (GET_CODE (SET_DEST (sets[0].rtl)) == ZERO_EXTRACT
+	       && CONST_INT_P (src_eqv)
+	       && CONST_INT_P (XEXP (SET_DEST (sets[0].rtl), 1))
+	       && CONST_INT_P (XEXP (SET_DEST (sets[0].rtl), 2)))
+	{
+	  rtx dest_reg = XEXP (SET_DEST (sets[0].rtl), 0);
+	  rtx width = XEXP (SET_DEST (sets[0].rtl), 1);
+	  rtx pos = XEXP (SET_DEST (sets[0].rtl), 2);
+	  HOST_WIDE_INT val = INTVAL (src_eqv);
+	  HOST_WIDE_INT mask;
+	  unsigned int shift;
+	  if (BITS_BIG_ENDIAN)
+	    shift = GET_MODE_PRECISION (GET_MODE (dest_reg))
+	      - INTVAL (pos) - INTVAL (width);
+	  else
+	    shift = INTVAL (pos);
+	  if (INTVAL (width) == HOST_BITS_PER_WIDE_INT)
+	    mask = ~(HOST_WIDE_INT) 0;
+	  else
+	    mask = ((HOST_WIDE_INT) 1 << INTVAL (width)) - 1;
+	  val = (val >> shift) & mask;
+	  src_eqv = GEN_INT (val);
+	}
+    }
 
   /* Set sets[i].src_elt to the class each source belongs to.
      Detect assignments from or to volatile things
diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 80c0adb..cdb70ac 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -5228,7 +5228,8 @@ set_for_reg_notes (rtx insn)
   reg = SET_DEST (pat);
 
   /* Notes apply to the contents of a STRICT_LOW_PART.  */
-  if (GET_CODE (reg) == STRICT_LOW_PART)
+  if (GET_CODE (reg) == STRICT_LOW_PART
+      || GET_CODE (reg) == ZERO_EXTRACT)
     reg = XEXP (reg, 0);
 
   /* Check that we have a register.  */
-- 
1.9.1