[wasm] Refactor handling of operands to bytecodes.

[wasm] Refactor handling of operands to bytecodes.

This cleans up and simplifyies handling the bytes followin an opcode
with little helper structs that will be useful in the interpreter and
already have been in keeping OpcodeArity and OpcodeLength up to date
with the decoder.

R=bradnelson@chromium.org, ahaas@chromium.org
BUG=

Committed: https://crrev.com/9c006b724ee2a094b57ffcdf2cd0da060af1f821
Cr-Commit-Position: refs/heads/master@{#33723}

[bradnelson, 2016-02-03 19:44:48]

lgtm

https://codereview.chromium.org/1664883002/diff/1/src/wasm/ast-decoder.cc
File src/wasm/ast-decoder.cc (right):

https://codereview.chromium.org/1664883002/diff/1/src/wasm/ast-decoder.cc#new...
src/wasm/ast-decoder.cc:665: len = 1 + operand.length;
FWIW, the bookkeeping on these lengths is getting pretty tedious to follow, but
not sure of a suggestion on how to make it clearer.

https://codereview.chromium.org/1664883002/diff/1/src/wasm/ast-decoder.h
File src/wasm/ast-decoder.h (right):

https://codereview.chromium.org/1664883002/diff/1/src/wasm/ast-decoder.h#newc...
src/wasm/ast-decoder.h:152: DCHECK(i >= 0 && i < table_count);
compare sign mismatch

[titzer, 2016-02-04 09:34:08]

https://codereview.chromium.org/1664883002/diff/1/src/wasm/ast-decoder.cc
File src/wasm/ast-decoder.cc (right):

https://codereview.chromium.org/1664883002/diff/1/src/wasm/ast-decoder.cc#new...
src/wasm/ast-decoder.cc:665: len = 1 + operand.length;
On 2016/02/03 19:44:47, bradnelson wrote:
> FWIW, the bookkeeping on these lengths is getting pretty tedious to follow,
but
> not sure of a suggestion on how to make it clearer.

I was thinking of renaming {len} to {total_len} passing in {&total_len} to the
constructor, so that the operand will compute the total length of the opcode,
but I kept it simple here in that *Operand structs only compute the length of
the operand itself (i.e. excluding the bytecode).

https://codereview.chromium.org/1664883002/diff/1/src/wasm/ast-decoder.h
File src/wasm/ast-decoder.h (right):

https://codereview.chromium.org/1664883002/diff/1/src/wasm/ast-decoder.h#newc...
src/wasm/ast-decoder.h:152: DCHECK(i >= 0 && i < table_count);
On 2016/02/03 19:44:47, bradnelson wrote:
> compare sign mismatch

Yeah, dang it, for the 200th time. (This is one of my worst peeves with C++. The
code already checks for i >= 0, and even so, comparing integers on the same
number line is the obviously correct thing to do. So much for compilers.)

[titzer, 2016-02-04 10:03:20]

The CQ bit was checked by titzer@chromium.org

[titzer, 2016-02-04 10:03:20]

The patchset sent to the CQ was uploaded after l-g-t-m from
bradnelson@chromium.org
Link to the patchset: https://codereview.chromium.org/1664883002/#ps40001
(title: " ")

[commit-bot: I haz the power, 2016-02-04 10:03:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1664883002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1664883002/40001

[commit-bot: I haz the power, 2016-02-04 10:16:24]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-02-04 10:16:54]

Description was changed from

==========
[wasm] Refactor handling of operands to bytecodes.

This cleans up and simplifyies handling the bytes followin an opcode
with little helper structs that will be useful in the interpreter and
already have been in keeping OpcodeArity and OpcodeLength up to date
with the decoder.

R=bradnelson@chromium.org, ahaas@chromium.org
BUG=
==========

to

==========
[wasm] Refactor handling of operands to bytecodes.

This cleans up and simplifyies handling the bytes followin an opcode
with little helper structs that will be useful in the interpreter and
already have been in keeping OpcodeArity and OpcodeLength up to date
with the decoder.

R=bradnelson@chromium.org, ahaas@chromium.org
BUG=

Committed: https://crrev.com/9c006b724ee2a094b57ffcdf2cd0da060af1f821
Cr-Commit-Position: refs/heads/master@{#33723}
==========

[commit-bot: I haz the power, 2016-02-04 10:16:55]

Patchset 3 (id:??) landed as
https://crrev.com/9c006b724ee2a094b57ffcdf2cd0da060af1f821
Cr-Commit-Position: refs/heads/master@{#33723}