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[gcov] Fix non-determinism (DenseMap iteration order) of checksum computation 

... by using MapVector. The issue was caused by 63182c2ac0.

Also use stable_partition instead of partition to get stable results
across different STL implementations.
This commit is contained in:
Fangrui Song 2020-10-05 12:39:19 -07:00
parent 3641d375f6
commit e338f8fe69
1 changed files with 9 additions and 14 deletions
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23
llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
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@ -16,6 +16,7 @@
#include "CFGMST.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Sequence.h"
#include "llvm/ADT/Statistic.h"
@ -396,7 +397,7 @@ namespace {
}
GCOVBlock &getBlock(const BasicBlock *BB) {
return Blocks.find(BB)->second;
return Blocks.find(const_cast<BasicBlock *>(BB))->second;
}
GCOVBlock &getEntryBlock() { return EntryBlock; }
@ -462,14 +463,8 @@ namespace {
write(E.second);
}
}
std::vector<GCOVBlock *> Sorted;
Sorted.reserve(Blocks.size());
for (auto &It : Blocks)
Sorted.push_back(&It.second);
llvm::sort(Sorted, [](GCOVBlock *x, GCOVBlock *y) {
return x->Number < y->Number;
});
for (GCOVBlock &Block : make_pointee_range(Sorted)) {
for (auto &It : Blocks) {
const GCOVBlock &Block = It.second;
if (Block.OutEdges.empty()) continue;
write(GCOV_TAG_ARCS);
@ -482,8 +477,8 @@ namespace {
}
// Emit lines for each block.
for (GCOVBlock &Block : make_pointee_range(Sorted))
Block.writeOut();
for (auto &It : Blocks)
It.second.writeOut();
}
public:
@ -492,7 +487,7 @@ namespace {
uint32_t Ident;
uint32_t FuncChecksum;
int Version;
DenseMap<BasicBlock *, GCOVBlock> Blocks;
MapVector<BasicBlock *, GCOVBlock> Blocks;
GCOVBlock EntryBlock;
GCOVBlock ReturnBlock;
};
@ -889,8 +884,8 @@ bool GCOVProfiler::emitProfileNotes(
return E->Removed || (!E->InMST && !E->Place);
});
const size_t Measured =
llvm::partition(MST.AllEdges,
[](std::unique_ptr<Edge> &E) { return E->Place; }) -
llvm::stable_partition(
MST.AllEdges, [](std::unique_ptr<Edge> &E) { return E->Place; }) -
MST.AllEdges.begin();
for (size_t I : llvm::seq<size_t>(0, Measured)) {
Edge &E = *MST.AllEdges[I];