On 02/07/14 08:52, Tom de Vries wrote:
> On 01-07-14 21:47, Jeff Law wrote:
>> On 07/01/14 13:27, Tom de Vries wrote:
>>> So my question is: is the combination of '&' and '+' supported ? If so,
>>> what is the exact semantics ? If not, should we warn or give an error ?
> >
>> I don't think we can define any reasonable semantics for &+. My
>> recommendation
>> would be for this to be considered a hard error.
>>
>
Why would this be any different in behaviour from use of operand tie
constraints to early-clobber?
In my view, it says that this operand is safe from the early-clobber
limitation, but other operands are not and need to be in other registers.
Eg op0 ("=&r") op1("0") op2("r") says that op1 must be the same register
as op0, but op2 must be a different register, so A = A <op> B is ok, but
A = A <op> A is not.
R.
> [ move discussion from gcc ml to gcc-patches ml ]
>
> Attached patch detects the combination of + and & constrains during genrecog,
> and generates an error like this:
> ...
> /home/vries/gcc_versions/devel/src/gcc/config/aarch64/aarch64-simd.md:1020:
> operand 0 has in-out reload, incompatible with earlyclobber
> /home/vries/gcc_versions/devel/src/gcc/config/aarch64/aarch64-simd.md:1020:
> operand 0 has in-out reload, incompatible with earlyclobber
> /home/vries/gcc_versions/devel/src/gcc/config/aarch64/aarch64-simd.md:1020:
> operand 0 has in-out reload, incompatible with earlyclobber
> make[2]: *** [s-recog] Error 1
> ...
> The error triggers three times, once for each mode iterator element.
>
> OK if x86_64 bootstrap succeeds ?
>
> Thanks,
> - Tom
>
>
> 0004-Don-t-allow-earlyclobber-modifier-with-read-write-mo.patch
>
>
> 2014-07-02 Tom de Vries <t...@codesourcery.com>
>
> * genrecog.c (validate_pattern): Don't allow earlyclobber constraint
> modifier with read/write constraint modifier.
>
> diff --git a/gcc/genrecog.c b/gcc/genrecog.c
> index 457b59c..ad709ee 100644
> --- a/gcc/genrecog.c
> +++ b/gcc/genrecog.c
> @@ -481,6 +481,13 @@ validate_pattern (rtx pattern, rtx insn, rtx set, int
> set_code)
> rtx_name[GET_CODE (insn)]);
> }
>
> + if (constraints0 == '+'
> + && strchr (XSTR (pattern, 2), '&') != NULL)
> + error_with_line (pattern_lineno,
> + "operand %d has in-out reload, incompatible with"
> + " earlyclobber",
> + XINT (pattern, 0));
> +
> /* A MATCH_OPERAND that is a SET should have an output reload. */
> else if (set && constraints0)
> {
>
