MIPS: Refactor simulator and add selection instructions for r6.

MIPS: Refactor simulator and add selection instructions for r6.

TEST=
BUG=

Committed: https://crrev.com/f00b4e94fb99f68cb6845e6d704001f341c484b9
Cr-Commit-Position: refs/heads/master@{#27530}

[dusmil.imgtec, 2015-03-30 16:07:22]

dusan.milosavljevic@imgtec.com changed reviewers:
+ akos.palfi@imgtec.com, balazs.kilvady@imgtec.com, paul.lind@imgtec.com

[balazs.kilvady, 2015-03-30 17:02:46]

LGTM.

[dusmil.imgtec, 2015-03-30 17:12:53]

The CQ bit was checked by dusan.milosavljevic@imgtec.com

[commit-bot: I haz the power, 2015-03-30 17:13:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1046873004/1

[commit-bot: I haz the power, 2015-03-30 17:37:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-30 17:37:23]

Patchset 1 (id:??) landed as
https://crrev.com/f00b4e94fb99f68cb6845e6d704001f341c484b9
Cr-Commit-Position: refs/heads/master@{#27530}

[paul.l..., 2015-03-31 04:02:01]

Post-landing comments: nice refactoring! One test bug, and a few nits.

https://codereview.chromium.org/1046873004/diff/1/src/mips/disasm-mips.cc
File src/mips/disasm-mips.cc (right):

https://codereview.chromium.org/1046873004/diff/1/src/mips/disasm-mips.cc#new...
src/mips/disasm-mips.cc:106: void DecodeTypeRegisterSPECIAL(Instruction* instr);
nit: consider naming here, maybe: DecodeTypeRegisterSpecial()

https://codereview.chromium.org/1046873004/diff/1/src/mips/simulator-mips.cc
File src/mips/simulator-mips.cc (right):

https://codereview.chromium.org/1046873004/diff/1/src/mips/simulator-mips.cc#...
src/mips/simulator-mips.cc:2261: case TRUNC_L_D: {  // Mips32r2 instruction.
This comment (and many other like it need to be changed, now that we have r6. In
"the old days", this signified instructions not available on r1 or Loongson.
This could now be 'Mips32r2/r6 instruction' or 'Mips32r2+ instruction' or '>=
Mips32r2 instruction'. Let's discuss, and pick something.

https://codereview.chromium.org/1046873004/diff/1/src/mips64/simulator-mips64.cc
File src/mips64/simulator-mips64.cc (right):

https://codereview.chromium.org/1046873004/diff/1/src/mips64/simulator-mips64...
src/mips64/simulator-mips64.cc:2409: case ROUND_L_D: {  // Mips64r2 instruction.
As mentioned in simulator-mips.cc: this is for mips64r2 and r6.

https://codereview.chromium.org/1046873004/diff/1/test/cctest/test-assembler-...
File test/cctest/test-assembler-mips.cc (right):

https://codereview.chromium.org/1046873004/diff/1/test/cctest/test-assembler-...
test/cctest/test-assembler-mips.cc:52: CcTest::InitializeVM();
Test needs to be run only on mips32r6 - it uses r6-specific instructions.