We agreed to go with this patch for now.
Landed in r196119 along with a comment explaining the technique used.
Alp.
On 12/11/2013 18:19, Benjamin Kramer wrote:
On 09.11.2013, at 00:31, Alp Toker <[email protected]> wrote:
On 08/11/2013 20:26, Manuel Klimek wrote:
raw_ostream &RewriteBuffer::write(raw_ostream &os) const {
- // FIXME: eliminate the copy by writing out each chunk at a time
- os << std::string(begin(), end());
+ for (RopePieceBTreeIterator I = begin(), E = end(); I != E;
+ I.MoveToNextPiece())
+ os << I.piece();
return os;
Why's it not ok to write ++I? (if there is a good reason, a comment
might help...)
The operator iterates individually through each character in the source
file, whereas MoveToNextPiece() gets us directly to the next chunk
letting us write/memcpy() directly into the output stream.
Is this functionality actually used anywhere? Having an iterator over a set of
StringRefs would make more sense than one over individual characters IMO.
- Ben
Looking through SVN history I see that the efficient accessors were
'cleaned' away as dead code and it ended up as a FIXME.
Will add a comment.
Alp.
On Fri, Nov 8, 2013 at 1:41 AM, Alp Toker <[email protected]
<mailto:[email protected]>> wrote:
Updated patch to use StringRef instead of RopePieceBTreeIterator
internals.
Check it out
Alp.
On 07/11/2013 07:08, Alp Toker wrote:
Rewrite was previously allocating potentially huge std::strings with
each call and filling it one character at a time.
This has become a hot path for Refactoring, Modernize, FixIt,
Format,
and particularly ARCMT/ObjCMT which call it multiple times on
the full
source tree -- so copying out contiguous chunks while avoiding large
allocations is a good idea.
This commit preserves the existing interface of RewriteRope and
pokes
into it directly for access to the byte vectors.
Resolves a FIXME back from r101521. No change in behaviour.
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