nicolas/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

[ThinLTO] Add a recursive step in Metadata lazy-loading

Browse Source 
Summary:
Without this, we're stressing the RAUW of unique nodes,
which is a costly operation. This is intended to limit
the number of RAUW, and is very effective on the total
link-time of opt with ThinLTO, before:

  real 4m4.587s  user 15m3.401s  sys 0m23.616s

after:

  real 3m25.261s user 12m22.132s sys 0m24.152s

Reviewers: tejohnson, pcc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28751

llvm-svn: 292420
This commit is contained in:
Mehdi Amini
2017-01-18 18:36:21 +00:00
parent 19b911cb75
commit 67d2cc1fad
2 changed files with 20 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
llvm/lib/Bitcode/Reader/MetadataLoader.cpp
View File

@@ -768,13 +768,12 @@ void MetadataLoader::MetadataLoaderImpl::lazyLoadOneMetadata(
unsigned ID, PlaceholderQueue &Placeholders) {
assert(ID < (MDStringRef.size()) + GlobalMetadataBitPosIndex.size());
assert(ID >= MDStringRef.size() && "Unexpected lazy-loading of MDString");
#ifndef NDEBUG
// Lookup first if the metadata hasn't already been loaded.
if (auto *MD = MetadataList.lookup(ID)) {
auto *N = dyn_cast_or_null<MDNode>(MD);
assert(N && N->isTemporary() && "Lazy loading an already loaded metadata");
if (!N->isTemporary())
return;
}
#endif
SmallVector<uint64_t, 64> Record;
StringRef Blob;
IndexCursor.JumpToBit(GlobalMetadataBitPosIndex[ID - MDStringRef.size()]);
@@ -827,8 +826,22 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
auto getMD = [&](unsigned ID) -> Metadata * {
if (ID < MDStringRef.size())
return lazyLoadOneMDString(ID);
if (!IsDistinct)
if (!IsDistinct) {
if (auto *MD = MetadataList.lookup(ID))
return MD;
// If lazy-loading is enabled, we try recursively to load the operand
// instead of creating a temporary.
if (ID < (MDStringRef.size() + GlobalMetadataBitPosIndex.size())) {
// Create a temporary for the node that is referencing the operand we
// will lazy-load. It is needed before recursing in case there are
// uniquing cycles.
MetadataList.getMetadataFwdRef(NextMetadataNo);
lazyLoadOneMetadata(ID, Placeholders);
return MetadataList.lookup(ID);
}
// Return a temporary.
return MetadataList.getMetadataFwdRef(ID);
}
if (auto *MD = MetadataList.getMetadataIfResolved(ID))
return MD;
return &Placeholders.getPlaceholderOp(ID);