[llvm-commits] CVS: llvm/lib/Transforms/Instrumentation/ProfilePaths/CombineBranch.cpp
Brian Gaeke
gaeke at cs.uiuc.edu
Tue Mar 30 13:54:01 PST 2004
Changes in directory llvm/lib/Transforms/Instrumentation/ProfilePaths:
CombineBranch.cpp updated: 1.7 -> 1.8
---
Log message:
Start cleaning up this pass so that I can debug it.
---
Diffs of the changes: (+34 -80)
Index: llvm/lib/Transforms/Instrumentation/ProfilePaths/CombineBranch.cpp
diff -u llvm/lib/Transforms/Instrumentation/ProfilePaths/CombineBranch.cpp:1.7 llvm/lib/Transforms/Instrumentation/ProfilePaths/CombineBranch.cpp:1.8
--- llvm/lib/Transforms/Instrumentation/ProfilePaths/CombineBranch.cpp:1.7 Thu Nov 20 12:25:21 2003
+++ llvm/lib/Transforms/Instrumentation/ProfilePaths/CombineBranch.cpp Tue Mar 30 13:53:46 2004
@@ -7,57 +7,48 @@
//
//===----------------------------------------------------------------------===//
//
-// Pass to instrument loops
-//
-// At every backedge, insert a counter for that backedge and a call function
+// Combine branches
//
//===----------------------------------------------------------------------===//
-#include "llvm/Analysis/Dominators.h"
#include "llvm/Support/CFG.h"
-#include "llvm/Constants.h"
-#include "llvm/iMemory.h"
-#include "llvm/GlobalVariable.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/iOther.h"
-#include "llvm/iOperators.h"
#include "llvm/iTerminators.h"
#include "llvm/iPHINode.h"
-#include "llvm/Module.h"
#include "llvm/Function.h"
#include "llvm/Pass.h"
namespace llvm {
-//this is used to color vertices
-//during DFS
-
-enum Color{
- WHITE,
- GREY,
- BLACK
-};
-
namespace {
struct CombineBranches : public FunctionPass {
private:
- //DominatorSet *DS;
+ /// Possible colors that a vertex can have during depth-first search for
+ /// back-edges.
+ ///
+ enum Color { WHITE, GREY, BLACK };
+
void getBackEdgesVisit(BasicBlock *u,
std::map<BasicBlock *, Color > &color,
std::map<BasicBlock *, int > &d,
int &time,
std::map<BasicBlock *, BasicBlock *> &be);
void removeRedundant(std::map<BasicBlock *, BasicBlock *> &be);
- void getBackEdges(Function &F);
public:
bool runOnFunction(Function &F);
};
- RegisterOpt<CombineBranches> X("branch-combine", "Multiple backedges going to same target are merged");
+ RegisterOpt<CombineBranches>
+ X("branch-combine", "Multiple backedges going to same target are merged");
}
-//helper function to get back edges: it is called by
-//the "getBackEdges" function below
+/// getBackEdgesVisit - Get the back-edges of the control-flow graph for this
+/// function. We proceed recursively using depth-first search. We get
+/// back-edges by associating a time and a color with each vertex. The time of a
+/// vertex is the time when it was first visited. The color of a vertex is
+/// initially WHITE, changes to GREY when it is first visited, and changes to
+/// BLACK when ALL its neighbors have been visited. So we have a back edge when
+/// we meet a successor of a node with smaller time, and GREY color.
+///
void CombineBranches::getBackEdgesVisit(BasicBlock *u,
std::map<BasicBlock *, Color > &color,
std::map<BasicBlock *, int > &d,
@@ -69,27 +60,24 @@
d[u]=time;
for (succ_iterator vl = succ_begin(u), ve = succ_end(u); vl != ve; ++vl){
-
BasicBlock *BB = *vl;
- if(color[BB]!=GREY && color[BB]!=BLACK){
+ if(color[BB]!=GREY && color[BB]!=BLACK)
getBackEdgesVisit(BB, color, d, time, be);
- }
//now checking for d and f vals
else if(color[BB]==GREY){
//so v is ancestor of u if time of u > time of v
- if(d[u] >= d[BB]){
- //u->BB is a backedge
+ if(d[u] >= d[BB]) // u->BB is a backedge
be[u] = BB;
- }
}
}
color[u]=BLACK;//done with visiting the node and its neighbors
}
-//look at all BEs, and remove all BEs that are dominated by other BE's in the
-//set
+/// removeRedundant - Remove all back-edges that are dominated by other
+/// back-edges in the set.
+///
void CombineBranches::removeRedundant(std::map<BasicBlock *, BasicBlock *> &be){
std::vector<BasicBlock *> toDelete;
std::map<BasicBlock *, int> seenBB;
@@ -126,17 +114,13 @@
std::map<PHINode *, std::vector<unsigned int> > phiMap;
-
for(std::vector<BasicBlock *>::iterator VBI = sameTarget.begin(),
VBE = sameTarget.end(); VBI != VBE; ++VBI){
- //std::cerr<<(*VBI)->getName()<<"\n";
-
BranchInst *ti = cast<BranchInst>((*VBI)->getTerminator());
unsigned char index = 1;
- if(ti->getSuccessor(0) == MI->second){
+ if(ti->getSuccessor(0) == MI->second)
index = 0;
- }
ti->setSuccessor(index, newBB);
@@ -146,10 +130,8 @@
if (PHINode *phiInst = dyn_cast<PHINode>(BB2Inst)){
int bbIndex;
bbIndex = phiInst->getBasicBlockIndex(*VBI);
- if(bbIndex>=0){
+ if(bbIndex>=0)
phiMap[phiInst].push_back(bbIndex);
- //phiInst->setIncomingBlock(bbIndex, newBB);
- }
}
}
}
@@ -177,53 +159,25 @@
PI->first->addIncoming(phiNode, newBB);
}
- //std::cerr<<"%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\n";
- //std::cerr<<MI->second;
- //std::cerr<<"-----------------------------------\n";
- //std::cerr<<newBB;
- //std::cerr<<"END%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\n";
-
}
}
}
-//getting the backedges in a graph
-//Its a variation of DFS to get the backedges in the graph
-//We get back edges by associating a time
-//and a color with each vertex.
-//The time of a vertex is the time when it was first visited
-//The color of a vertex is initially WHITE,
-//Changes to GREY when it is first visited,
-//and changes to BLACK when ALL its neighbors
-//have been visited
-//So we have a back edge when we meet a successor of
-//a node with smaller time, and GREY color
-void CombineBranches::getBackEdges(Function &F){
- std::map<BasicBlock *, Color > color;
- std::map<BasicBlock *, int> d;
- std::map<BasicBlock *, BasicBlock *> be;
- int time=0;
- getBackEdgesVisit(F.begin(), color, d, time, be);
-
- removeRedundant(be);
-}
-
-//Per function pass for inserting counters and call function
+/// runOnFunction - Per function pass for combining branches.
+///
bool CombineBranches::runOnFunction(Function &F){
-
- if(F.isExternal()) {
+ if (F.isExternal ())
return false;
- }
- //if(F.getName() == "main"){
- // F.setName("llvm_gprof_main");
- //}
-
- //std::cerr<<F;
- //std::cerr<<"///////////////////////////////////////////////\n";
- getBackEdges(F);
+ // Find and remove "redundant" back-edges.
+ std::map<BasicBlock *, Color> color;
+ std::map<BasicBlock *, int> d;
+ std::map<BasicBlock *, BasicBlock *> be;
+ int time = 0;
+ getBackEdgesVisit (F.begin (), color, d, time, be);
+ removeRedundant (be);
- return true;
+ return true; // FIXME: assumes a modification was always made.
}
} // End llvm namespace
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