MIPS: Use Lsa/Dlsa when possible.

For MIPS32R6 replace instances of "sll/addu" to calculate the
address of an item in an array with "lsa". For other versions of
MIPS32 use the "sll/addu" sequence. Encapsulate this logic in an
assembler method to eliminate having a lot of statements like
"if (IsR6()) { ... } else { ... }" scattered throughout the code.

MIPS64 always supports R6. This means that all instances of
"dsll/daddu" used to calculate the address of an item in an array
can be replaced by "dlsa" so there is no need to encapsulate
conditional logic in a special method. The code can just emit
"dlsa" directly.

Test: mma -j2 ART_TEST_OPTIMIZING=true test-art-target-run-test
Tested on MIPS32, and MIPS64 QEMU.
Test: "make test-art-target-gtest32" on CI20 board.
Test: "cd art; test/testrunner/testrunner.py --target --optimizing --32"
      on CI20 board.

Change-Id: Ibe5facc1bc2a6a7a6584e23d3a48e163ae38077d
5 files changed