* Bug in binop rotate ?
@ 2009-10-17 14:42 Andrew Hutchinson
2009-10-17 16:01 ` Richard Guenther
0 siblings, 1 reply; 3+ messages in thread
From: Andrew Hutchinson @ 2009-10-17 14:42 UTC (permalink / raw)
To: GCC Development
I have been adding rotate capability to AVR port and have come across
what I think is bug in
optabs.c: expand_binop()
This occurs during a rotate expansion. For example
target = op0 rotated by op1
In the particular situation (code extract below) it tries a reverse
rotate of (bits - op1). Where this expression is expanded as a simple
integer,
a negation or subtraction depending on type of op1 and target.
The expansion of the subtraction is using the mode of the target - I
believe it should be using the mode of op1.
The mode of the rotation amount need not be the same as the target.
target:DI = Op0:DI rotate op1:HI
In my testcase it is not and I get asserts latter in simplfy_rtx.
The negation mode looks equally wrong.
Am I mistaken?
/* If we were trying to rotate, and that didn't work, try rotating
the other direction before falling back to shifts and bitwise-or. */
if (((binoptab == rotl_optab
&& optab_handler (rotr_optab, mode)->insn_code != CODE_FOR_nothing)
|| (binoptab == rotr_optab
&& optab_handler (rotl_optab, mode)->insn_code != CODE_FOR_nothing))
&& mclass == MODE_INT)
{
optab otheroptab = (binoptab == rotl_optab ? rotr_optab : rotl_optab);
rtx newop1;
unsigned int bits = GET_MODE_BITSIZE (mode);
if (CONST_INT_P (op1))
newop1 = GEN_INT (bits - INTVAL (op1));
else if (targetm.shift_truncation_mask (mode) == bits - 1)
newop1 = negate_rtx (mode, op1);
else
newop1 = expand_binop (mode, sub_optab,
GEN_INT (bits), op1,
NULL_RTX, unsignedp, OPTAB_DIRECT);
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Bug in binop rotate ?
2009-10-17 14:42 Bug in binop rotate ? Andrew Hutchinson
@ 2009-10-17 16:01 ` Richard Guenther
2009-10-17 16:18 ` Andrew Hutchinson
0 siblings, 1 reply; 3+ messages in thread
From: Richard Guenther @ 2009-10-17 16:01 UTC (permalink / raw)
To: Andrew Hutchinson; +Cc: GCC Development
On Sat, Oct 17, 2009 at 3:47 PM, Andrew Hutchinson
<andrewhutchinson@cox.net> wrote:
> I have been adding rotate capability to AVR port and have come across what I
> think is bug in
> optabs.c: expand_binop()
>
> This occurs during a rotate expansion. For example
>
> target = op0 rotated by op1
>
> In the particular situation (code extract below) it tries a reverse rotate
> of (bits - op1). Where this expression is expanded as a simple integer,
> a negation or subtraction depending on type of op1 and target.
>
> The expansion of the subtraction is using the mode of the target - I believe
> it should be using the mode of op1.
> The mode of the rotation amount need not be the same as the target.
>
> target:DI = Op0:DI rotate op1:HI
>
> In my testcase it is not and I get asserts latter in simplfy_rtx.
>
> The negation mode looks equally wrong.
>
> Am I mistaken?
I think you are correct.
Richard.
>
> /* If we were trying to rotate, and that didn't work, try rotating
> the other direction before falling back to shifts and bitwise-or. */
> if (((binoptab == rotl_optab
> && optab_handler (rotr_optab, mode)->insn_code != CODE_FOR_nothing)
> || (binoptab == rotr_optab
> && optab_handler (rotl_optab, mode)->insn_code != CODE_FOR_nothing))
> && mclass == MODE_INT)
> {
> optab otheroptab = (binoptab == rotl_optab ? rotr_optab : rotl_optab);
> rtx newop1;
> unsigned int bits = GET_MODE_BITSIZE (mode);
>
> if (CONST_INT_P (op1))
> newop1 = GEN_INT (bits - INTVAL (op1));
> else if (targetm.shift_truncation_mask (mode) == bits - 1)
> newop1 = negate_rtx (mode, op1);
> else
> newop1 = expand_binop (mode, sub_optab,
> GEN_INT (bits), op1,
> NULL_RTX, unsignedp, OPTAB_DIRECT);
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Bug in binop rotate ?
2009-10-17 16:01 ` Richard Guenther
@ 2009-10-17 16:18 ` Andrew Hutchinson
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Hutchinson @ 2009-10-17 16:18 UTC (permalink / raw)
To: GCC Development
Thanks for your review.
I have submitted bug report.
Richard Guenther wrote:
> On Sat, Oct 17, 2009 at 3:47 PM, Andrew Hutchinson
> <andrewhutchinson@cox.net> wrote:
>
>> I have been adding rotate capability to AVR port and have come across what I
>> think is bug in
>> optabs.c: expand_binop()
>>
>> This occurs during a rotate expansion. For example
>>
>> target = op0 rotated by op1
>>
>> In the particular situation (code extract below) it tries a reverse rotate
>> of (bits - op1). Where this expression is expanded as a simple integer,
>> a negation or subtraction depending on type of op1 and target.
>>
>> The expansion of the subtraction is using the mode of the target - I believe
>> it should be using the mode of op1.
>> The mode of the rotation amount need not be the same as the target.
>>
>> target:DI = Op0:DI rotate op1:HI
>>
>> In my testcase it is not and I get asserts latter in simplfy_rtx.
>>
>> The negation mode looks equally wrong.
>>
>> Am I mistaken?
>>
>
> I think you are correct.
>
> Richard.
>
>
>> /* If we were trying to rotate, and that didn't work, try rotating
>> the other direction before falling back to shifts and bitwise-or. */
>> if (((binoptab == rotl_optab
>> && optab_handler (rotr_optab, mode)->insn_code != CODE_FOR_nothing)
>> || (binoptab == rotr_optab
>> && optab_handler (rotl_optab, mode)->insn_code != CODE_FOR_nothing))
>> && mclass == MODE_INT)
>> {
>> optab otheroptab = (binoptab == rotl_optab ? rotr_optab : rotl_optab);
>> rtx newop1;
>> unsigned int bits = GET_MODE_BITSIZE (mode);
>>
>> if (CONST_INT_P (op1))
>> newop1 = GEN_INT (bits - INTVAL (op1));
>> else if (targetm.shift_truncation_mask (mode) == bits - 1)
>> newop1 = negate_rtx (mode, op1);
>> else
>> newop1 = expand_binop (mode, sub_optab,
>> GEN_INT (bits), op1,
>> NULL_RTX, unsignedp, OPTAB_DIRECT);
>>
>>
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2009-10-17 16:01 ` Richard Guenther
2009-10-17 16:18 ` Andrew Hutchinson
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