The negdi2 patterns for ARM and Thumb-2 are duplicated because Thumb-2 doesn't suppor...

The negdi2 patterns for ARM and Thumb-2 are duplicated because Thumb-2 doesn't support RSC with an immediate.

The negdi2 patterns for ARM and Thumb-2 are duplicated because Thumb-2
doesn't support RSC with an immediate.  We can however emulate RSC with
zero using a shifted SBC.  If we add this to subsi3_carryin the negdi
patterns can be merged, simplifying things a bit.  This should generate
identical code in all cases.

    gcc/
        * config/arm/arm.md (subsi3_carryin): Add Thumb-2 RSC #0.
        (arm_negdi2) Rename to negdi2_insn, allow on Thumb-2.
        * config/arm/thumb2.md (thumb2_negdi2): Remove pattern.

From-SVN: r243745