https://codereview.chromium.org/1321663003/diff/40001/test/cctest/interpreter/test-bytecode-generator.cc
File test/cctest/interpreter/test-bytecode-generator.cc (right):
https://codereview.chromium.org/1321663003/diff/40001/test/cctest/interpreter/test-bytecode-generator.cc#newcode257
test/cctest/interpreter/test-bytecode-generator.cc:257: { 3.14, 3.14 }
On 2015/08/27 19:36:29, Michael Starzinger wrote:
On 2015/08/27 16:34:07, rmcilroy wrote:
> Michi - looks like double literals aren't de-duped by the parser (we
get a new
> HeapNumber each time). Is this done elsewhere or have we always had
a new
> HeapNumber for each double literal?
Not sure I understand your comment correctly. How would the parser
de-dupe
literals? That would make the AST degenerate into a DAG if we would do
that. Or
am I missing something here?
Compilers can de-dupe the values. One mechanism of de-duping would be
GVN which
makes sure that identical nodes in the graph are coalesced. Both
Hydrogen and
TurboFan do that.
Ah, I think now I understand where you are coming from, I think your
question was whether AstValue::Internalize should canonicalize
HeapNumbers or not. Maeh, the data-structure for canonicalizing them
would probably end up eating more memory than the duped HeapNumbers, I
don't think that would buy us anything besides complexity.
Rather the question is, why do we "internalize" double literals in the
first place. One could argue that it should be the responsibility of the
compiler to decide whether and where to allocate HeapNumbers. But that's
opening a can of worms. I suggest we don't go there.
https://codereview.chromium.org/1321663003/
--
--
v8-dev mailing list
[email protected]
http://groups.google.com/group/v8-dev
---
You received this message because you are subscribed to the Google Groups "v8-dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/d/optout.
