This patchset improves zero extend costs and code generation.

This patchset improves zero extend costs and code generation.

When zero extending a 32-bit register, we emit a "mov", but currently
report the cost of the "mov" incorrectly.

In terms of speed, we currently say the cost is that of an extend
operation. But the cost of a "mov" is the cost of 1 instruction, so fix
that.

In terms of size, we currently say that the "mov" takes 0 instructions.
Fix it by changing it to 1.

Bootstrapped and tested on aarch64-none-elf.

    gcc/
	* config/aarch64/aarch64.c (aarch64_rtx_costs): Fix cost of zero extend.

From-SVN: r238820