RFA: patch for PR59535

[Vladimir Makarov <vmakarov at redhat dot com>]

  The following patch improves code size for ARM.  Before the patch 
CSiBE size generated by GCC configured --with-arch=armv7-a 
--with-fpu=vfpv3-d16 --with-float=hard (with -mthumb) was

2414926

After the patch the size is

2396798

For comparison, when the reload pass is used the size is

2400154

The change in arm.h is to prevent reloading sp as an address by LRA. 
Reload has no such problem as it uses legitimate address hook and LRA 
mostly relies on base_reg_class.

Richard, is this part ok to commit to the trunk?

The change in lra-constraints.c is for correct alternative choice in 
move patterns when pseudo is of class of general reg and one alternative 
contains lo regs and another one contains hi regs.

The patch was bootstrapped on x86/x86-64 and arm.

2014-02-07  Vladimir Makarov  <vmakarov@redhat.com>

        PR rtl-optimization/59535
        * lra-constraints.c (process_alt_operands): Encourage alternative
        when unassigned pseudo class is superset of the alternative class.
        * config/arm/arm.h (MODE_BASE_REG_CLASS): Return CORE_REGS for
        Thumb2 for LRA.

Attachment: pr59535.patch
Description: Text document