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LV info on machine instructions

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@359 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ruchira Sasanka
2001-08-20 21:11:01 +00:00
parent cc3a0dbb85
commit 9166181257
8 changed files with 196 additions and 130 deletions
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115
include/llvm/Analysis/LiveVar/FunctionLiveVarInfo.h
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@@ -3,36 +3,48 @@
Date: Jun 30, 01
Purpose:
This is the interface for live variable info of a method that is required by
any other part of the compiler
This is the interface for live variable info of a method that is required
by any other part of the compiler
It should be called like:
It must be called like:
MethodLiveVarInfo MLVI( Mehtod *); // initializes data structures
MLVI.analyze(); // do the actural live variable anal
MLVI.analyze(); // do the actural live variable anal
After the analysis, getInSetOfBB or getOutSetofBB can be called to get
live var info of a BB
live var info of a BB.
The live var set before an instruction can be constructed in several ways:
The live var set before an instruction can be obtained in 2 ways:
1. Use the OutSet and applyTranferFuncForInst(const Instruction *const Inst)
1. Use the method getLiveVarSetAfterInst(Instruction *) to get the LV Info
just after an instruction. (also exists getLiveVarSetBeforeInst(..))
This function caluclates the LV info for a BB only once and caches that
info. If the cache does not contain the LV info of the instruction, it
calculates the LV info for the whole BB and caches them.
Getting liveVar info this way uses more memory since, LV info should be
cached. However, if you need LV info of nearly all the instructions of a
BB, this is the best and simplest interfrace.
2. Use the OutSet and applyTranferFuncForInst(const Instruction *const Inst)
declared in LiveVarSet and traverse the instructions of a basic block in
reverse (using const_reverse_iterator in the BB class).
This is the most efficient method if you need LV info for several (all)
instructions in a BasicBlock. An example is given below:
This is the most memory efficient method if you need LV info for
only several instructions in a BasicBlock. An example is given below:
LiveVarSet LVSet; // this will be the set used to traverse through each BB
// Initialize LVSet so that it is the same as OutSet of the BB
// Initialize LVSet so that it is the same as OutSet of the BB
LVSet.setUnion( LVI->getOutSetOfBB( *BBI ) );
BasicBlock::InstListType::const_reverse_iterator
InstIterator = InstListInBB.rbegin(); // get the reverse it for inst in BB
InstIterator = InstListInBB.rbegin(); // get the rev iter for inst in BB
// iterate over all the instructions in BB in reverse
// iterate over all the instructions in BB in reverse
for( ; InstIterator != InstListInBB.rend(); InstIterator++) {
//...... all code here which uses LVSet ........
@@ -45,28 +57,16 @@
See buildInterferenceGraph() for the above example.
2. Use the function getLiveVarSetBeforeInst(Instruction *) to get the LV Info
just before an instruction.
This function caluclates the LV info for a BB only once and caches that
info. If the cache does not contain the LV info of the instruction, it
calculates the LV info for the whole BB and caches them.
Getting liveVar info this way uses more memory since, LV info should be
cached.
**BUGS: Cannot be called on a method prototype because the BB front()
iterator causes a seg fault in CFG.h (Chris will fix this)
So, currently, DO NOT call this for method prototypes.
*/
#ifndef METH_LIVE_VAR_INFO_H
#define METH_LIVE_VAR_INFO_H
// for printing out debug messages
// set DEBUG_LV for printing out debug messages
// if DEBUG_LV is 1 normal output messages
// if DEBUG_LV is 2 extensive debug info for each instr
#define DEBUG_LV (1)
#include "LiveVarSet.h"
@@ -82,38 +82,65 @@
class MethodLiveVarInfo
{
private:
const Method *Meth; // Live var anal is done on this method
// set by constructor
BBToBBLiveVarMapType BB2BBLVMap; // A map betwn the BasicBlock and BBLiveVar
// Live var anal is done on this method - set by constructor
const Method *const Meth;
InstToLiveVarSetMapType Inst2LVSetMap; // Instruction to LiveVarSet Map
//- for providing LV info for each inst
// A map betwn the BasicBlock and BBLiveVar
BBToBBLiveVarMapType BB2BBLVMap;
void constructBBs(); // constructs BBLiveVars and init Def and In sets
bool doSingleBackwardPass(); // do one backward pass over the CFG
// Machine Instr to LiveVarSet Map for providing LVset BEFORE each inst
MInstToLiveVarSetMapType MInst2LVSetBI;
// Machine Instr to LiveVarSet Map for providing LVset AFTER each inst
MInstToLiveVarSetMapType MInst2LVSetAI;
// True if the analyze() method has been called. This is checked when
// getInSet/OutSet is called to prevent calling those methods before analyze
bool HasAnalyzed;
// --------- private methods -----------------------------------------
// constructs BBLiveVars and init Def and In sets
void constructBBs();
// do one backward pass over the CFG
bool doSingleBackwardPass();
// calculates live var sets for instructions in a BB
void calcLiveVarSetsForBB(const BasicBlock *const BB);
public:
MethodLiveVarInfo(Method *const Meth); // constructor
MethodLiveVarInfo(const Method *const Meth); // constructor
~MethodLiveVarInfo(); // destructor
~MethodLiveVarInfo(); // destructor
void analyze(); // performs a liver var analysis of a single method
// performs a liver var analysis of a single method
void analyze();
// gets OutSet of a BB
inline const LiveVarSet *getOutSetOfBB( const BasicBlock *const BB) const {
// gets OutSet of a BB
inline const LiveVarSet *getOutSetOfBB( const BasicBlock *const BB) const {
assert( HasAnalyzed && "call analyze() before calling this" );
return ( (* (BB2BBLVMap.find(BB)) ).second )->getOutSet();
}
// gets InSet of a BB
// gets InSet of a BB
inline const LiveVarSet *getInSetOfBB( const BasicBlock *const BB) const {
assert( HasAnalyzed && "call analyze() before calling this" );
return ( (* (BB2BBLVMap.find(BB)) ).second )->getInSet();
}
// gets the Live var set before an instruction
const LiveVarSet *
MethodLiveVarInfo::getLiveVarSetBeforeInst(const Instruction *const Inst);
// gets the Live var set BEFORE an instruction
const LiveVarSet * getLiveVarSetBeforeMInst(const MachineInstr *const Inst,
const BasicBlock *const CurBB);
// gets the Live var set AFTER an instruction
const LiveVarSet * getLiveVarSetAfterMInst(const MachineInstr *const MInst,
const BasicBlock *const CurBB);
};