PNaCl translator: combine insertelement / extractelement patterns generated by the toolchain into s…

PNaCl translator: combine insertelement / extractelement patterns generated by the toolchain into shufflevector

shufflevector isn't part of the PNaCl ABI, insertelement /
extractelement sequences are instead generated, but they help in
generating higher performance code. This pass recognizes the patterns at
translation time and reconstructs shufflevector, allowing the generated
code to perform better.

R=dschuff@chromium.org
TEST= ninja check
BUG= http://code.google.com/p/nativeclient/issues/detail?id=2205

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-llvm.git;a=commit;h=1eecfea

[Derek Schuff, 2014-05-12 20:49:22]

https://codereview.chromium.org/282553003/diff/40001/lib/Transforms/NaCl/Comb...
File lib/Transforms/NaCl/CombineVectorInstructions.cpp (right):

https://codereview.chromium.org/282553003/diff/40001/lib/Transforms/NaCl/Comb...
lib/Transforms/NaCl/CombineVectorInstructions.cpp:39: // TODO(jfb) This function
is as-is from instcombine.
there's nothing to do specified in this TODO.

https://codereview.chromium.org/282553003/diff/40001/lib/Transforms/NaCl/Comb...
lib/Transforms/NaCl/CombineVectorInstructions.cpp:262: Idx >= NumVectorElts ?
Idx - NumVectorElts : Idx + NumVectorElts;
80 cols

[JF, 2014-05-12 22:00:00]

Update, fixed dschuff's comments and implemented DCE as discussed offline with
dschuff (since we don't want to run a full DCE, and we have extra information
about what can be killed from this pass).

I'll implement the load/store combination soon.

https://codereview.chromium.org/282553003/diff/40001/lib/Transforms/NaCl/Comb...
File lib/Transforms/NaCl/CombineVectorInstructions.cpp (right):

https://codereview.chromium.org/282553003/diff/40001/lib/Transforms/NaCl/Comb...
lib/Transforms/NaCl/CombineVectorInstructions.cpp:39: // TODO(jfb) This function
is as-is from instcombine.
On 2014/05/12 20:49:22, Derek Schuff wrote:
> there's nothing to do specified in this TODO. 

Done.

https://codereview.chromium.org/282553003/diff/40001/lib/Transforms/NaCl/Comb...
lib/Transforms/NaCl/CombineVectorInstructions.cpp:262: Idx >= NumVectorElts ?
Idx - NumVectorElts : Idx + NumVectorElts;
On 2014/05/12 20:49:22, Derek Schuff wrote:
> 80 cols

Done.

[Derek Schuff, 2014-05-12 22:13:55]

lgtm

[JF, 2014-05-12 22:48:22]

Committed patchset #4 manually as r1eecfea (presubmit successful).