Use range information for optimizing integer boxing and fix bug in range analysis.

Use range information for optimizing integer boxing and fix bug in range analysis.

1. When the input to a BoxInteger operation is in smi-range, we can eliminate
the range check and just perform a smi-tag operation on the input.

2. There was a bug in checking for smi-overflow for range boundaries: Calling Smi::IsValid
with a int64_t argument resulted in silent truncation of the input and therefore a wrong result.

Compiling with -Wconversion would have caught this, but currently we cannot compile with this flag
because of too many broken places.

Instead, I removed Smi::IsValid64 and created one variant Smi::IsValid that is specialized for the
input type with a template parameter. This way calling Smi::IsValid is always safe and will never
 result in silent alteration of the input argument.

R=vegorov@google.com

Committed: https://code.google.com/p/dart/source/detail?r=37657

[Vyacheslav Egorov (Google), 2014-06-24 12:18:12]

lgtm

https://codereview.chromium.org/353513002/diff/1/runtime/vm/intermediate_lang...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/353513002/diff/1/runtime/vm/intermediate_lang...
runtime/vm/intermediate_language.cc:3292: 
one more empty line

https://codereview.chromium.org/353513002/diff/1/runtime/vm/object.h
File runtime/vm/object.h (right):

https://codereview.chromium.org/353513002/diff/1/runtime/vm/object.h#newcode5032
runtime/vm/object.h:5032: if (sizeof(value) < sizeof(kMinValue)) {
We also need to check that it is integral type because on x64 sizeof(float) <
sizeof(intptr_t).

std::numeric_limits<T>::is_integer

https://codereview.chromium.org/353513002/diff/1/runtime/vm/object.h#newcode5035
runtime/vm/object.h:5035: if (static_cast<T>(-1) < 0) {
I would really prefer we write C++ here:

std::numeric_limits<T>::is_signed

[Florian Schneider, 2014-06-24 12:35:06]

https://codereview.chromium.org/353513002/diff/1/runtime/vm/intermediate_lang...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/353513002/diff/1/runtime/vm/intermediate_lang...
runtime/vm/intermediate_language.cc:3292: 
On 2014/06/24 12:18:12, Vyacheslav Egorov (Google) wrote:
> one more empty line

Done.

https://codereview.chromium.org/353513002/diff/1/runtime/vm/object.h
File runtime/vm/object.h (right):

https://codereview.chromium.org/353513002/diff/1/runtime/vm/object.h#newcode5032
runtime/vm/object.h:5032: if (sizeof(value) < sizeof(kMinValue)) {
On 2014/06/24 12:18:12, Vyacheslav Egorov (Google) wrote:
> We also need to check that it is integral type because on x64 sizeof(float) <
> sizeof(intptr_t).
> 
> std::numeric_limits<T>::is_integer

Done. Added a COMPILE_ASSERT because we should never invoke it with a
non-integral type.

https://codereview.chromium.org/353513002/diff/1/runtime/vm/object.h#newcode5035
runtime/vm/object.h:5035: if (static_cast<T>(-1) < 0) {
On 2014/06/24 12:18:12, Vyacheslav Egorov (Google) wrote:
> I would really prefer we write C++ here:
> 
> std::numeric_limits<T>::is_signed

Done.

[Florian Schneider, 2014-06-24 13:42:01]

Committed patchset #3 manually as r37657 (presubmit successful).