[wasm] Fix wasm decoder tracing for prefix opcodes.

[wasm] Fix wasm decoder tracing for prefix opcodes.

Using --trace-wasm-decoder prints unknowns for prefix opcodes, example:

  @3      #01:Block               |  env = 0x5547c10, state = R, reason = block:start, control = #0:Start

  @4      #14:GetLocal            | i@4:GetLocal[0]
  @6      #e5:Unknown             | s@6:Unknown
  @8      #15:SetLocal            | s@8:SetLocal[1]
  @10     #14:GetLocal            | s@8:SetLocal[1] i@10:GetLocal[0]
  @12     #14:GetLocal            | s@8:SetLocal[1] i@10:GetLocal[0] s@12:GetLocal[1]
  @14     #cb:I8Const             | s@8:SetLocal[1] i@10:GetLocal[0] s@12:GetLocal[1] i@14:I8Const
  @16     #e5:Unknown             | s@8:SetLocal[1] i@10:GetLocal[0] i@16:Unknown

Fixed to print:

  @3        #01:Block               |  env = 0x45cac10, state = R, reason = block:start, control = #0:Start

  @4        #14:GetLocal            | i@4:GetLocal[0]
  @6    #e5 #1b:I32x4Splat          | s@6:I32x4Splat
  @8        #15:SetLocal            | s@8:SetLocal[1]
  @10       #14:GetLocal            | s@8:SetLocal[1] i@10:GetLocal[0]
  @12       #14:GetLocal            | s@8:SetLocal[1] i@10:GetLocal[0] s@12:GetLocal[1]
  @14       #cb:I8Const             | s@8:SetLocal[1] i@10:GetLocal[0] s@12:GetLocal[1] i@14:I8Const
  @16   #e5 #1c:I32x4ExtractLane    | s@8:SetLocal[1] i@10:GetLocal[0] i@16:I32x4ExtractLane

R=ahaas@chromium.org, bbudge@chromium.org

Committed: https://crrev.com/eed164b30421590af7359536dd2fc965c76b6b3c
Cr-Commit-Position: refs/heads/master@{#39142}

[gdeepti, 2016-09-02 05:13:29]

The CQ bit was checked by gdeepti@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-09-02 05:13:35]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-02 05:15:05]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-09-02 05:15:06]

Dry run: Try jobs failed on following builders:
  v8_linux64_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_rel_ng/builds/12018)
  v8_linux_dbg_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_dbg_ng/builds/12012)
  v8_linux_mipsel_compile_rel on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_mipsel_compile_rel...)
  v8_mac_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_mac_rel_ng/builds/8086)

[gdeepti, 2016-09-02 05:16:00]

The CQ bit was checked by gdeepti@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-09-02 05:16:05]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-02 05:18:35]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-09-02 05:18:36]

Dry run: Try jobs failed on following builders:
  v8_linux64_avx2_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng/buil...)
  v8_linux64_gyp_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_gyp_rel_ng/build...)
  v8_linux64_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_rel_ng/builds/12021)
  v8_linux_dbg_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_dbg_ng/builds/12016)
  v8_linux_gcc_compile_rel on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_gcc_compile_rel/bu...)
  v8_linux_mipsel_compile_rel on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_mipsel_compile_rel...)
  v8_linux_nodcheck_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_nodcheck_rel_ng/bu...)
  v8_mac_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_mac_rel_ng/builds/8090)

[gdeepti, 2016-09-02 05:46:15]

The CQ bit was checked by gdeepti@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-09-02 05:46:26]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-02 06:14:17]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-09-02 06:14:19]

Dry run: This issue passed the CQ dry run.

[ahaas, 2016-09-02 12:10:21]

lgtm, I wonder if this change could be tested in some meaningful way though.

[gdeepti, 2016-09-02 17:49:04]

Not that I can think of, will take a look and follow up with a test.

[gdeepti, 2016-09-02 17:49:10]

The CQ bit was checked by gdeepti@chromium.org

[commit-bot: I haz the power, 2016-09-02 17:49:15]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-02 17:51:36]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-09-02 17:52:25]

Description was changed from

==========
[wasm] Fix wasm decoder tracing for prefix opcodes.

Using --trace-wasm-decoder prints unknowns for prefix opcodes, example:

  @3      #01:Block               |  env = 0x5547c10, state = R, reason =
block:start, control = #0:Start

  @4      #14:GetLocal            | i@4:GetLocal[0]
  @6      #e5:Unknown             | s@6:Unknown
  @8      #15:SetLocal            | s@8:SetLocal[1]
  @10     #14:GetLocal            | s@8:SetLocal[1] i@10:GetLocal[0]
  @12     #14:GetLocal            | s@8:SetLocal[1] i@10:GetLocal[0]
s@12:GetLocal[1]
  @14     #cb:I8Const             | s@8:SetLocal[1] i@10:GetLocal[0]
s@12:GetLocal[1] i@14:I8Const
  @16     #e5:Unknown             | s@8:SetLocal[1] i@10:GetLocal[0]
i@16:Unknown

Fixed to print:

  @3        #01:Block               |  env = 0x45cac10, state = R, reason =
block:start, control = #0:Start

  @4        #14:GetLocal            | i@4:GetLocal[0]
  @6    #e5 #1b:I32x4Splat          | s@6:I32x4Splat
  @8        #15:SetLocal            | s@8:SetLocal[1]
  @10       #14:GetLocal            | s@8:SetLocal[1] i@10:GetLocal[0]
  @12       #14:GetLocal            | s@8:SetLocal[1] i@10:GetLocal[0]
s@12:GetLocal[1]
  @14       #cb:I8Const             | s@8:SetLocal[1] i@10:GetLocal[0]
s@12:GetLocal[1] i@14:I8Const
  @16   #e5 #1c:I32x4ExtractLane    | s@8:SetLocal[1] i@10:GetLocal[0]
i@16:I32x4ExtractLane

R=ahaas@chromium.org, bbudge@chromium.org
==========

to

==========
[wasm] Fix wasm decoder tracing for prefix opcodes.

Using --trace-wasm-decoder prints unknowns for prefix opcodes, example:

  @3      #01:Block               |  env = 0x5547c10, state = R, reason =
block:start, control = #0:Start

  @4      #14:GetLocal            | i@4:GetLocal[0]
  @6      #e5:Unknown             | s@6:Unknown
  @8      #15:SetLocal            | s@8:SetLocal[1]
  @10     #14:GetLocal            | s@8:SetLocal[1] i@10:GetLocal[0]
  @12     #14:GetLocal            | s@8:SetLocal[1] i@10:GetLocal[0]
s@12:GetLocal[1]
  @14     #cb:I8Const             | s@8:SetLocal[1] i@10:GetLocal[0]
s@12:GetLocal[1] i@14:I8Const
  @16     #e5:Unknown             | s@8:SetLocal[1] i@10:GetLocal[0]
i@16:Unknown

Fixed to print:

  @3        #01:Block               |  env = 0x45cac10, state = R, reason =
block:start, control = #0:Start

  @4        #14:GetLocal            | i@4:GetLocal[0]
  @6    #e5 #1b:I32x4Splat          | s@6:I32x4Splat
  @8        #15:SetLocal            | s@8:SetLocal[1]
  @10       #14:GetLocal            | s@8:SetLocal[1] i@10:GetLocal[0]
  @12       #14:GetLocal            | s@8:SetLocal[1] i@10:GetLocal[0]
s@12:GetLocal[1]
  @14       #cb:I8Const             | s@8:SetLocal[1] i@10:GetLocal[0]
s@12:GetLocal[1] i@14:I8Const
  @16   #e5 #1c:I32x4ExtractLane    | s@8:SetLocal[1] i@10:GetLocal[0]
i@16:I32x4ExtractLane

R=ahaas@chromium.org, bbudge@chromium.org

Committed: https://crrev.com/eed164b30421590af7359536dd2fc965c76b6b3c
Cr-Commit-Position: refs/heads/master@{#39142}
==========

[commit-bot: I haz the power, 2016-09-02 17:52:26]

Patchset 2 (id:??) landed as
https://crrev.com/eed164b30421590af7359536dd2fc965c76b6b3c
Cr-Commit-Position: refs/heads/master@{#39142}

[bbudge, 2016-09-02 18:08:49]

lgtm