Re: [PATCH v3 1/3] rtl: directly handle MEM in gen_highpart [PR102125]
Richard Earnshaw writes:
> On 13/09/2021 10:38, Richard Sandiford via Gcc-patches wrote:
>> Richard Earnshaw via Gcc-patches writes:
>>> gen_lowpart_general handles forming a lowpart of a MEM by using
>>> adjust_address to rework and validate a new version of the MEM.
>>> Do the same for gen_highpart rather than calling simplify_gen_subreg
>>> for this case.
>>
>> Looks OK, but what went wrong with the existing code? Did
>> simplify_gen_subreg refuse to handle a MEM that you wanted
>> it to handle, or did the validize_mem go wrong for some reason?
>
> It refused to handle it and simply returned (subreg (mem)) - see the
> discussion on version 1 of the patch series.
OK, that's good then. The patch is OK from my POV too FWIW.
Richard
>>> gcc/ChangeLog:
>>>
>>> PR target/102125
>>> * emit-rtl.c (gen_highpart): Use adjust_address to handle
>>> MEM rather than calling simplify_gen_subreg.
>>> ---
>>> gcc/emit-rtl.c | 23 +--
>>> 1 file changed, 13 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
>>> index 77ea8948ee8..0ba110879aa 100644
>>> --- a/gcc/emit-rtl.c
>>> +++ b/gcc/emit-rtl.c
>>> @@ -1585,19 +1585,22 @@ gen_highpart (machine_mode mode, rtx x)
>>> gcc_assert (known_le (msize, (unsigned int) UNITS_PER_WORD)
>>> || known_eq (msize, GET_MODE_UNIT_SIZE (GET_MODE (x;
>>>
>>> - result = simplify_gen_subreg (mode, x, GET_MODE (x),
>>> - subreg_highpart_offset (mode, GET_MODE (x)));
>>> - gcc_assert (result);
>>> -
>>> - /* simplify_gen_subreg is not guaranteed to return a valid operand for
>>> - the target if we have a MEM. gen_highpart must return a valid
>>> operand,
>>> - emitting code if necessary to do so. */
>>> - if (MEM_P (result))
>>> + /* gen_lowpart_common handles a lot of special cases due to needing to
>>> handle
>>> + paradoxical subregs; it only calls simplify_gen_subreg when certain
>>> that
>>> + it will produce something meaningful. The only case we need to handle
>>> + specially here is MEM. */
>>> + if (MEM_P (x))
>>> {
>>> - result = validize_mem (result);
>>> - gcc_assert (result);
>>> + poly_int64 offset = subreg_highpart_offset (mode, GET_MODE (x));
>>> + return adjust_address (x, mode, offset);
>>> }
>>>
>>> + result = simplify_gen_subreg (mode, x, GET_MODE (x),
>>> + subreg_highpart_offset (mode, GET_MODE (x)));
>>> + /* Since we handle MEM directly above, we should never get a MEM back
>>> + from simplify_gen_subreg. */
>>> + gcc_assert (result && !MEM_P (result));
>>> +
>>> return result;
>>> }
>>>
Re: [PATCH v3 1/3] rtl: directly handle MEM in gen_highpart [PR102125]
On 13/09/2021 10:38, Richard Sandiford via Gcc-patches wrote:
Richard Earnshaw via Gcc-patches writes:
gen_lowpart_general handles forming a lowpart of a MEM by using
adjust_address to rework and validate a new version of the MEM.
Do the same for gen_highpart rather than calling simplify_gen_subreg
for this case.
Looks OK, but what went wrong with the existing code? Did
simplify_gen_subreg refuse to handle a MEM that you wanted
it to handle, or did the validize_mem go wrong for some reason?
It refused to handle it and simply returned (subreg (mem)) - see the
discussion on version 1 of the patch series.
R.
Thanks,
Richard
gcc/ChangeLog:
PR target/102125
* emit-rtl.c (gen_highpart): Use adjust_address to handle
MEM rather than calling simplify_gen_subreg.
---
gcc/emit-rtl.c | 23 +--
1 file changed, 13 insertions(+), 10 deletions(-)
diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 77ea8948ee8..0ba110879aa 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -1585,19 +1585,22 @@ gen_highpart (machine_mode mode, rtx x)
gcc_assert (known_le (msize, (unsigned int) UNITS_PER_WORD)
|| known_eq (msize, GET_MODE_UNIT_SIZE (GET_MODE (x;
- result = simplify_gen_subreg (mode, x, GET_MODE (x),
- subreg_highpart_offset (mode, GET_MODE (x)));
- gcc_assert (result);
-
- /* simplify_gen_subreg is not guaranteed to return a valid operand for
- the target if we have a MEM. gen_highpart must return a valid operand,
- emitting code if necessary to do so. */
- if (MEM_P (result))
+ /* gen_lowpart_common handles a lot of special cases due to needing to handle
+ paradoxical subregs; it only calls simplify_gen_subreg when certain that
+ it will produce something meaningful. The only case we need to handle
+ specially here is MEM. */
+ if (MEM_P (x))
{
- result = validize_mem (result);
- gcc_assert (result);
+ poly_int64 offset = subreg_highpart_offset (mode, GET_MODE (x));
+ return adjust_address (x, mode, offset);
}
+ result = simplify_gen_subreg (mode, x, GET_MODE (x),
+ subreg_highpart_offset (mode, GET_MODE (x)));
+ /* Since we handle MEM directly above, we should never get a MEM back
+ from simplify_gen_subreg. */
+ gcc_assert (result && !MEM_P (result));
+
return result;
}
Re: [PATCH v3 1/3] rtl: directly handle MEM in gen_highpart [PR102125]
Richard Earnshaw via Gcc-patches writes:
> gen_lowpart_general handles forming a lowpart of a MEM by using
> adjust_address to rework and validate a new version of the MEM.
> Do the same for gen_highpart rather than calling simplify_gen_subreg
> for this case.
Looks OK, but what went wrong with the existing code? Did
simplify_gen_subreg refuse to handle a MEM that you wanted
it to handle, or did the validize_mem go wrong for some reason?
Thanks,
Richard
> gcc/ChangeLog:
>
> PR target/102125
> * emit-rtl.c (gen_highpart): Use adjust_address to handle
> MEM rather than calling simplify_gen_subreg.
> ---
> gcc/emit-rtl.c | 23 +--
> 1 file changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
> index 77ea8948ee8..0ba110879aa 100644
> --- a/gcc/emit-rtl.c
> +++ b/gcc/emit-rtl.c
> @@ -1585,19 +1585,22 @@ gen_highpart (machine_mode mode, rtx x)
>gcc_assert (known_le (msize, (unsigned int) UNITS_PER_WORD)
> || known_eq (msize, GET_MODE_UNIT_SIZE (GET_MODE (x;
>
> - result = simplify_gen_subreg (mode, x, GET_MODE (x),
> - subreg_highpart_offset (mode, GET_MODE (x)));
> - gcc_assert (result);
> -
> - /* simplify_gen_subreg is not guaranteed to return a valid operand for
> - the target if we have a MEM. gen_highpart must return a valid operand,
> - emitting code if necessary to do so. */
> - if (MEM_P (result))
> + /* gen_lowpart_common handles a lot of special cases due to needing to
> handle
> + paradoxical subregs; it only calls simplify_gen_subreg when certain that
> + it will produce something meaningful. The only case we need to handle
> + specially here is MEM. */
> + if (MEM_P (x))
> {
> - result = validize_mem (result);
> - gcc_assert (result);
> + poly_int64 offset = subreg_highpart_offset (mode, GET_MODE (x));
> + return adjust_address (x, mode, offset);
> }
>
> + result = simplify_gen_subreg (mode, x, GET_MODE (x),
> + subreg_highpart_offset (mode, GET_MODE (x)));
> + /* Since we handle MEM directly above, we should never get a MEM back
> + from simplify_gen_subreg. */
> + gcc_assert (result && !MEM_P (result));
> +
>return result;
> }
>
Re: [PATCH v3 1/3] rtl: directly handle MEM in gen_highpart [PR102125]
On Fri, Sep 10, 2021 at 4:48 PM Richard Earnshaw wrote: > > > gen_lowpart_general handles forming a lowpart of a MEM by using > adjust_address to rework and validate a new version of the MEM. > Do the same for gen_highpart rather than calling simplify_gen_subreg > for this case. OK from my side. Thanks, Richard. > gcc/ChangeLog: > > PR target/102125 > * emit-rtl.c (gen_highpart): Use adjust_address to handle > MEM rather than calling simplify_gen_subreg. > --- > gcc/emit-rtl.c | 23 +-- > 1 file changed, 13 insertions(+), 10 deletions(-) >
[PATCH v3 1/3] rtl: directly handle MEM in gen_highpart [PR102125]
gen_lowpart_general handles forming a lowpart of a MEM by using
adjust_address to rework and validate a new version of the MEM.
Do the same for gen_highpart rather than calling simplify_gen_subreg
for this case.
gcc/ChangeLog:
PR target/102125
* emit-rtl.c (gen_highpart): Use adjust_address to handle
MEM rather than calling simplify_gen_subreg.
---
gcc/emit-rtl.c | 23 +--
1 file changed, 13 insertions(+), 10 deletions(-)
diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index 77ea8948ee8..0ba110879aa 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -1585,19 +1585,22 @@ gen_highpart (machine_mode mode, rtx x)
gcc_assert (known_le (msize, (unsigned int) UNITS_PER_WORD)
|| known_eq (msize, GET_MODE_UNIT_SIZE (GET_MODE (x;
- result = simplify_gen_subreg (mode, x, GET_MODE (x),
-subreg_highpart_offset (mode, GET_MODE (x)));
- gcc_assert (result);
-
- /* simplify_gen_subreg is not guaranteed to return a valid operand for
- the target if we have a MEM. gen_highpart must return a valid operand,
- emitting code if necessary to do so. */
- if (MEM_P (result))
+ /* gen_lowpart_common handles a lot of special cases due to needing to handle
+ paradoxical subregs; it only calls simplify_gen_subreg when certain that
+ it will produce something meaningful. The only case we need to handle
+ specially here is MEM. */
+ if (MEM_P (x))
{
- result = validize_mem (result);
- gcc_assert (result);
+ poly_int64 offset = subreg_highpart_offset (mode, GET_MODE (x));
+ return adjust_address (x, mode, offset);
}
+ result = simplify_gen_subreg (mode, x, GET_MODE (x),
+subreg_highpart_offset (mode, GET_MODE (x)));
+ /* Since we handle MEM directly above, we should never get a MEM back
+ from simplify_gen_subreg. */
+ gcc_assert (result && !MEM_P (result));
+
return result;
}
