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Switch to using edge profiling information as the basic source of profile info

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from using basic block counts.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12242 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2004-03-08 22:04:08 +00:00
parent 7d84dda560
commit 96ab5caf2d
2 changed files with 73 additions and 5 deletions
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52
lib/Analysis/ProfileInfo.cpp
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@@ -14,6 +14,8 @@
#include "llvm/Analysis/ProfileInfo.h"
#include "llvm/Pass.h"
#include "llvm/Support/CFG.h"
#include <set>
using namespace llvm;
// Register the ProfileInfo interface, providing a nice name to refer to.
@@ -23,6 +25,56 @@ namespace {
ProfileInfo::~ProfileInfo() {}
unsigned ProfileInfo::getExecutionCount(BasicBlock *BB) const {
pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
// Are there zero predecessors of this block?
if (PI == PE) {
// If this is the entry block, look for the Null -> Entry edge.
if (BB == &BB->getParent()->front())
return getEdgeWeight(0, BB);
else
return 0; // Otherwise, this is a dead block.
}
// Otherwise, if there are predecessors, the execution count of this block is
// the sum of the edge frequencies from the incoming edges. Note that if
// there are multiple edges from a predecessor to this block that we don't
// want to count its weight multiple times. For this reason, we keep track of
// the predecessors we've seen and only count them if we haven't run into them
// yet.
//
// We don't want to create an std::set unless we are dealing with a block that
// has a LARGE number of in-edges. Handle the common case of having only a
// few in-edges with special code.
//
BasicBlock *FirstPred = *PI;
unsigned Count = getEdgeWeight(FirstPred, BB);
++PI;
if (PI == PE) return Count; // Quick exit for single predecessor blocks
BasicBlock *SecondPred = *PI;
if (SecondPred != FirstPred) Count += getEdgeWeight(SecondPred, BB);
++PI;
if (PI == PE) return Count; // Quick exit for two predecessor blocks
BasicBlock *ThirdPred = *PI;
if (ThirdPred != FirstPred && ThirdPred != SecondPred)
Count += getEdgeWeight(ThirdPred, BB);
++PI;
if (PI == PE) return Count; // Quick exit for three predecessor blocks
std::set<BasicBlock*> ProcessedPreds;
ProcessedPreds.insert(FirstPred);
ProcessedPreds.insert(SecondPred);
ProcessedPreds.insert(ThirdPred);
for (; PI != PE; ++PI)
if (ProcessedPreds.insert(*PI).second)
Count += getEdgeWeight(*PI, BB);
return Count;
}
//===----------------------------------------------------------------------===//
// NoProfile ProfileInfo implementation