| Message ID | 87d2m9g7wi.fsf@talisman.default |
|---|---|
| State | New |
| Headers | show |
On 11/09/2013 05:57 AM, Richard Sandiford wrote: > "mode_for_size (MAX_BITSIZE_MODE_ANY_INT, MODE_INT, 0)" isn't safe > because the widest mode might not have an integer counterpart. > We can get the widest integer mode directly using MAX_MODE_INT. > > Tested on powerpc64-linux-gnu and by rerunning the assembly comparison. > OK to install? > > Thanks, > Richard > > > Index: gcc/simplify-rtx.c > =================================================================== > --- gcc/simplify-rtx.c 2013-11-09 09:39:28.925815686 +0000 > +++ gcc/simplify-rtx.c 2013-11-09 09:39:29.461819309 +0000 > @@ -1619,7 +1619,7 @@ simplify_const_unary_operation (enum rtx > a dangerous assumption as many times CONST_INTs are > created and used with garbage in the bits outside of the > precision of the implied mode of the const_int. */ > - op_mode = mode_for_size (MAX_BITSIZE_MODE_ANY_INT, MODE_INT, 0); > + op_mode = MAX_MODE_INT; > } > > real_from_integer (&d, mode, std::make_pair (op, op_mode), SIGNED); > @@ -1637,7 +1637,7 @@ simplify_const_unary_operation (enum rtx > a dangerous assumption as many times CONST_INTs are > created and used with garbage in the bits outside of the > precision of the implied mode of the const_int. */ > - op_mode = mode_for_size (MAX_BITSIZE_MODE_ANY_INT, MODE_INT, 0); > + op_mode = MAX_MODE_INT; > } > > real_from_integer (&d, mode, std::make_pair (op, op_mode), UNSIGNED); i guess you are correct. i had assumed that the MAX_BITSIZE.. would always relate to a real integer because partial int modes have to be based on an underlying mode. Obviously you have a counter example in mind, but this code is actually just as good so it ok to install. kenny
On Nov 9, 2013, at 2:57 AM, Richard Sandiford <rdsandiford@googlemail.com> wrote: > "mode_for_size (MAX_BITSIZE_MODE_ANY_INT, MODE_INT, 0)" isn't safe > because the widest mode might not have an integer counterpart. > We can get the widest integer mode directly using MAX_MODE_INT. > OK to install? Ah, curious. Ok. Long term, one might want a partial int mode that is larger that all in modes, and support conversions to/from those… but, to do that, we'd need a bit more code.
Index: gcc/simplify-rtx.c =================================================================== --- gcc/simplify-rtx.c 2013-11-09 09:39:28.925815686 +0000 +++ gcc/simplify-rtx.c 2013-11-09 09:39:29.461819309 +0000 @@ -1619,7 +1619,7 @@ simplify_const_unary_operation (enum rtx a dangerous assumption as many times CONST_INTs are created and used with garbage in the bits outside of the precision of the implied mode of the const_int. */ - op_mode = mode_for_size (MAX_BITSIZE_MODE_ANY_INT, MODE_INT, 0); + op_mode = MAX_MODE_INT; } real_from_integer (&d, mode, std::make_pair (op, op_mode), SIGNED); @@ -1637,7 +1637,7 @@ simplify_const_unary_operation (enum rtx a dangerous assumption as many times CONST_INTs are created and used with garbage in the bits outside of the precision of the implied mode of the const_int. */ - op_mode = mode_for_size (MAX_BITSIZE_MODE_ANY_INT, MODE_INT, 0); + op_mode = MAX_MODE_INT; } real_from_integer (&d, mode, std::make_pair (op, op_mode), UNSIGNED);