VM: Fix bug in canonicalization of identical in the optimizing compiler.

VM: Fix bug in canonicalization of identical in the optimizing compiler.

Make sure that BranchInstr::Canonicalize does not mutate it's input before
all conditions for the optimzations to take place are met. Otherwise, bailing out
leaves the affected comparison instruction in an invalid state.

BUG=https://code.google.com/p/dart/issues/detail?id=14109
R=srdjan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=28646

[srdjan, 2013-10-15 15:10:15]

lgtm

https://codereview.chromium.org/26451006/diff/1/runtime/vm/intermediate_langu...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/26451006/diff/1/runtime/vm/intermediate_langu...
runtime/vm/intermediate_language.cc:1520: ASSERT(!*negated);
It seems safer to set *negated to false here than to expect the caller to
initialize it to false.

https://codereview.chromium.org/26451006/diff/1/runtime/vm/intermediate_langu...
File runtime/vm/intermediate_language.h (right):

https://codereview.chromium.org/26451006/diff/1/runtime/vm/intermediate_langu...
runtime/vm/intermediate_language.h:2848: intptr_t token_pos_;
const

[Florian Schneider, 2013-10-15 15:15:03]

Thanks for the quick review!

https://codereview.chromium.org/26451006/diff/1/runtime/vm/intermediate_langu...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/26451006/diff/1/runtime/vm/intermediate_langu...
runtime/vm/intermediate_language.cc:1520: ASSERT(!*negated);
On 2013/10/15 15:10:16, srdjan wrote:
> It seems safer to set *negated to false here than to expect the caller to
> initialize it to false.

Done.

https://codereview.chromium.org/26451006/diff/1/runtime/vm/intermediate_langu...
File runtime/vm/intermediate_language.h (right):

https://codereview.chromium.org/26451006/diff/1/runtime/vm/intermediate_langu...
runtime/vm/intermediate_language.h:2848: intptr_t token_pos_;
On 2013/10/15 15:10:16, srdjan wrote:
> const

Done.

[Florian Schneider, 2013-10-15 15:15:53]

Committed patchset #1 manually as r28646 (presubmit successful).