Cache the results of slow math operations on machines that don't...

Cache the results of slow math operations on machines that don't
have hardware fpu instructions to execute them.

Committed: http://code.google.com/p/v8/source/detail?r=2790

[Søren Thygesen Gjesse, 2009-09-01 08:40:31]

LGTM

http://codereview.chromium.org/179059/diff/1/2
File src/heap.cc (right):

http://codereview.chromium.org/179059/diff/1/2#newcode3995
Line 3995: for (int i = 0; i < kCacheSize; i++) {
Would memcpy be faster here?

http://codereview.chromium.org/179059/diff/1/4
File src/heap.h (right):

http://codereview.chromium.org/179059/diff/1/4#newcode1532
Line 1532: static inline Object* Get(Type type, double input) {
Please add a (short) comment on this public Get function.

http://codereview.chromium.org/179059/diff/1/4#newcode1533
Line 1533: TranscendentalCache* cache = caches_[type];
The description says "Cache the results of slow math operations on machines that
don't have hardware fpu instructions to execute them.", however it looks as if
the cache is always enabled. Is that intentional?

[Erik Corry, 2009-09-01 09:02:28]

http://codereview.chromium.org/179059/diff/1/2
File src/heap.cc (right):

http://codereview.chromium.org/179059/diff/1/2#newcode3995
Line 3995: for (int i = 0; i < kCacheSize; i++) {
On 2009/09/01 08:40:31, Søren Gjesse wrote:
> Would memcpy be faster here?

Possibly, but I don't expect this function to be called all that often, and it
would look messier.

http://codereview.chromium.org/179059/diff/1/4
File src/heap.h (right):

http://codereview.chromium.org/179059/diff/1/4#newcode1533
Line 1533: TranscendentalCache* cache = caches_[type];
On 2009/09/01 08:40:31, Søren Gjesse wrote:
> The description says "Cache the results of slow math operations on machines
that
> don't have hardware fpu instructions to execute them.", however it looks as if
> the cache is always enabled. Is that intentional?

The cache only works in the runtime system.  If we have an instruction for the
transcendental then we generate it inline and never normally enter the runtime
system.