Re: [PATCH][ARM][cleanup] Use IN_RANGE more often

[Richard Earnshaw <Richard dot Earnshaw at foss dot arm dot com>]

On 15/04/15 16:22, Kyrill Tkachov wrote:
> Hi all,
> 
> This patch goes through the arm backend and replaces expressions of the
> form
> a >= lo && a <= hi with IN_RANGE (a, lo, hi) which is that tiny bit smaller
> and easier to read in my opinion. I guess there's also a chance it might
> make
> things infinitesimally faster since IN_RANGE evaluates 'a' only once.
> The patch also substitutes expressions like a > hi || a < lo with
> !IN_RANGE (a, lo, hi) which, again, conveys the intended meaning more
> clearly.
> I tried to make sure not to introduce any off-by-one errors and testing
> caught some that I had made while writing these.
> 
> Bootstrapped and tested arm-none-linux-gnueabihf. Built and run SPEC2006
> succesfully.
> 
> Ok for trunk once 5.1 is released?
> 

I think this is pretty obvious for those cases where the type of the
range is [unsigned] HOST_WIDE_INT, but much less obvious for those cases
where the type is just int, or unsigned.  Cases that I think need more
careful examination include vfp3_const_double_index and
aapcs_vfp_is_call_or_return_candidate, but I haven't gone through every
instance to check whether there are more cases.

I'd be particularly concerned about these if the widening of the result
caused a code quality regression on a native 32-bit machine (since HWI
is a 64-bit type).

R.

> Thanks,
> Kyrill
> 
> 2015-04-15  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
> 
>     * config/arm/arm.md (*zeroextractsi_compare0_scratch): Use IN_RANGE
>     instead of two compares.
>     (*ne_zeroextractsi): Likewise.
>     (*ite_ne_zeroextractsi): Likewise.
>     (load_multiple): Likewise.
>     (store_multiple): Likewise.
>     * config/arm/arm.h (IS_IWMMXT_REGNUM): Likewise.
>     (IS_IWMMXT_GR_REGNUM): Likewise.
>     (IS_VFP_REGNUM): Likewise.
>     * config/arm/arm.c (arm_return_in_memory): Likewise.
>     (aapcs_vfp_is_call_or_return_candidate): Likewise.
>     (thumb_find_work_register): Likewise.
>     (thumb2_legitimate_address_p): Likewise.
>     (arm_legitimate_index_p): Likewise.
>     (thumb2_legitimate_index_p): Likewise.
>     (thumb1_legitimate_address_p): Likewise.
>     (thumb_legitimize_address): Likewise.
>     (vfp3_const_double_index): Likewise.
>     (neon_immediate_valid_for_logic): Likewise.
>     (bounds_check): Likewise.
>     (load_multiple_sequence): Likewise.
>     (store_multiple_sequence): Likewise.
>     (offset_ok_for_ldrd_strd): Likewise.
>     (callee_saved_reg_p): Likewise.
>     (thumb2_emit_strd_push): Likewise.
>     (arm_output_load_gr): Likewise.
>     (arm_vector_mode_supported_p): Likewise.
>     * config/arm/neon.md (ashldi3_neon_noclobber): Likewise.
>     (ashrdi3_neon_imm_noclobber): Likewise.
>     (lshrdi3_neon_imm_noclobber): Likewise.
>     * config/arm/thumb1.md (*thumb1_addsi3): Likewise.
>     * config/arm/thumb2.md (define_peephole2's after orsi_not_shiftsi_si):
>     Likewise.