[linaro/gcc-4_9-branch] AArch64 costs model backports

[Yvan Roux]

Hi all,

we have backported a set of AArch64 costs model related revisions in
the linaro/gcc-4_9-branch at r211843.  The backported revisions are:

210493 : [AArch64 costs 1/18] Refactor aarch64_address_costs.
210494 : [AArch64 costs 2/18] Add cost tables for Cortex-A57
210495 : [AArch64 costs 3/18] Wrap aarch64_rtx_costs to dump verbose output
210496 : [AArch64 costs 4/18] Better estimate cost of building a constant
210497 : [AArch64 costs 5/18] Factor out common MULT cases
210498 : [AArch64 costs 6/18] Set default costs and handle vector modes.
210499 : [AArch64 costs 7/18] Improve SET cost.
210500 : [AArch64 costs 8/18] Cost memory accesses using address costs
210501 : [AArch64 costs 9/18] Better cost logical operations
210502 : [AArch64 costs 10/18] Improve costs for sign/zero extend operations
210503 : [AArch64 costs 11/18] Improve costs for rotate and shift operations.
210504 : [AArch64 costs 12/18] Improve costs for sign/zero extracts
210505 : [AArch64 costs 13/18] Improve costs for div/mod
210506 : [AArch64 costs 14/18] Cost comparisons, flag setting
operators and IF_THEN_ELSE
210507 : [AArch64 costs 15/18] Cost more Floating point RTX.
210508 : [AArch64 costs 16/18] Cost TRUNCATE
210509 : [AArch64 costs 17/18] Cost for SYMBOL_REF, HIGH and LO_SUM
210510 : [AArch64 costs 18/18] Dump a message if we are unable to cost an insn.
210512 : [AArch64 costs] Fixup to costing of FNMUL
211205 : aarch64_if_then_else_costs refactor
211206 : aarch64_if_then_else_costs

Thanks,
Yvan