[PATCH] D36235: [pdb/lld] Write a valid FPM

[Reid Kleckner via Phabricator via llvm-commits]

rnk added inline comments.


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Comment at: llvm/lib/DebugInfo/PDB/Native/PDBFileBuilder.cpp:167-169
+  FpmStream =
+      WritableMappedBlockStream::createFpmStream(Layout, MsfBuffer, Allocator);
+  FpmWriter = BinaryStreamWriter(*FpmStream);
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zturner wrote:
> zturner wrote:
> > rnk wrote:
> > > Why do you need to recreate the stream and writer?
> > The stream doesn't have methods to update its length, so we need a new stream, and the writer doesn't have a method to set the stream to a new stream.
> BTW, the cost of "making a new stream" is not high.  Nothing is really happening other than allocating a stream object and setting some of its fields.  So we're wasting one (small) heap allocated object, but there's no copying or anything going on.
Are you sure? `createFpmStream` above seems to initialize the stream to 0xFF, so it's probably like a 4K memset at least.


https://reviews.llvm.org/D36235