On Wed, Apr 11, 2012 at 7:21 AM, Richard Sandiford
<rdsandif...@googlemail.com> wrote:
> "H.J. Lu" <hongjiu...@intel.com> writes:
>> Hi,
>>
>> CSE turns (reg:DI 64)
>>
>> (insn 6 3 7 2 (set (reg:DI 64)
>> (sign_extend:DI (subreg/u:SI (reg/v/f:DI 63 [ addr ]) 0))) x.i:6 122
>> {*extendsidi2_rex64} (nil))
>>
>> into (reg/f:DI 64 [ addr ]). But nonzero_bits1 in rtlanal.c has
>>
>> #if defined(POINTERS_EXTEND_UNSIGNED) && !defined(HAVE_ptr_extend)
>> /* If pointers extend unsigned and this is a pointer in Pmode, say that
>> all the bits above ptr_mode are known to be zero. */
>> /* As we do not know which address space the pointer is refering to,
>> we can do this only if the target does not support different pointer
>> or address modes depending on the address space. */
>> if (target_default_pointer_address_modes_p ()
>> && POINTERS_EXTEND_UNSIGNED && GET_MODE (x) == Pmode
>> && REG_POINTER (x))
>> nonzero &= GET_MODE_MASK (ptr_mode);
>> #endif
>>
>> Setting REG_POINTER with incompatible pointer sign extension is wrong.
>> This patch adds a bool parameter to set_reg_attrs_from_value to
>> indicate if a register can be marked as a pointer. Does it look OK?
>>
>> Thanks.
>>
>>
>> H.J.
>> ---
>> gcc/
>>
>> 2012-04-05 H.J. Lu <hongjiu...@intel.com>
>>
>> PR rtl-optimization/52876
>> * emit-rtl.c (set_reg_attrs_from_value): Add a bool parameter
>> to indicate if a register can be a pointer.
>> (gen_reg_rtx_and_attrs): Pass true to set_reg_attrs_from_value.
>> (set_reg_attrs_for_parm): Likewise.
>>
>> * emit-rtl.h (set_reg_attrs_from_value): Add a bool parameter.
>>
>> * reginfo.c (reg_scan_mark_refs): Pass false to
>> set_reg_attrs_from_value with incompatible pointer sign
>> extension.
>
> Regardless of how it is currently used, I think gen_reg_rtx_and_attrs
> (another caller to set_reg_attrs_from_value) is supposed to be a fairly
> general function. So rather than apply a fix specific to regscan,
> I think it would be cleaner to redefine set_reg_attrs_from_value as
> taking an arbitrary value. The whole while loop:
>
> while (GET_CODE (src) == SIGN_EXTEND
> || GET_CODE (src) == ZERO_EXTEND
> || GET_CODE (src) == TRUNCATE
> || (GET_CODE (src) == SUBREG && subreg_lowpart_p (src)))
> src = XEXP (src, 0);
>
> would then move to set_reg_attrs_from_value, and the "can be pointer"
> thing hidden there. The regscan code would just be:
>
> if (REG_P (dest) && !REG_ATTRS (dest))
> set_reg_attrs_from_value (dest, src);
>
> Richard
Here is the updated patch to change set_reg_attrs_from_value to
take arbitrary value and check incompatible pointer sign
extension. OK for trunk if there are no regressions on Linux/x86-64?
Thanks.
--
H.J.
---
gcc/
2012-04-10 H.J. Lu <hongjiu...@intel.com>
PR rtl-optimization/52876
* emit-rtl.c (set_reg_attrs_from_value): Handle arbitrary value.
Don't call mark_reg_pointer for incompatible pointer sign
extension.
* reginfo.c (reg_scan_mark_refs): Call set_reg_attrs_from_value
directly.
gcc/testsuite
2012-04-10 H.J. Lu <hongjiu...@intel.com>
PR rtl-optimization/52876
* gcc.target/i386/pr52876.c: New.
gcc-pr52876-2.patch
Description: Binary data
