6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-11-02 07:11:49 +00:00
Code Issues Projects Releases Wiki Activity

Add capability of using pointer analysis to LICM

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3478 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2002-08-22 21:39:55 +00:00
parent b81258c278
commit f5e84aa088
1 changed files with 35 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
lib/Transforms/Scalar/LICM.cpp
View File

@ -18,8 +18,10 @@
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/iOperators.h"
#include "llvm/iPHINode.h"
#include "llvm/iMemory.h"
#include "llvm/Support/InstVisitor.h"
#include "llvm/Support/CFG.h"
#include "Support/STLExtras.h"
@ -31,6 +33,7 @@ static Statistic<> NumHoistedNPH("licm\t\t- Number of insts hoisted to multiple"
" loop preds (bad, no loop pre-header)");
static Statistic<> NumHoistedPH("licm\t\t- Number of insts hoisted to a loop "
"pre-header");
static Statistic<> NumHoistedLoads("licm\t\t- Number of load insts hoisted");
namespace {
struct LICM : public FunctionPass, public InstVisitor<LICM> {
@ -40,6 +43,7 @@ namespace {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.preservesCFG();
AU.addRequired<LoopInfo>();
AU.addRequired<AliasAnalysis>();
}
private:
@ -48,8 +52,9 @@ namespace {
//
std::vector<BasicBlock*> LoopPreds, LoopBackEdges;
Loop *CurLoop; // The current loop we are working on...
bool Changed; // Set to true when we change anything.
Loop *CurLoop; // The current loop we are working on...
bool Changed; // Set to true when we change anything.
AliasAnalysis *AA; // Currently AliasAnalysis information
// visitLoop - Hoist expressions out of the specified loop...
void visitLoop(Loop *L);
@ -70,6 +75,11 @@ namespace {
//
void hoist(Instruction &I);
// pointerInvalidatedByLoop - Return true if the body of this loop may store
// into the memory location pointed to by V.
//
bool pointerInvalidatedByLoop(Value *V);
// isLoopInvariant - Return true if the specified value is loop invariant
inline bool isLoopInvariant(Value *V) {
if (Instruction *I = dyn_cast<Instruction>(V))
@ -94,6 +104,13 @@ namespace {
}
void visitShiftInst(ShiftInst &I) { visitBinaryOperator((Instruction&)I); }
void visitLoadInst(LoadInst &LI) {
assert(!LI.hasIndices());
if (isLoopInvariant(LI.getOperand(0)) &&
!pointerInvalidatedByLoop(LI.getOperand(0)))
hoist(LI);
}
void visitGetElementPtrInst(GetElementPtrInst &GEPI) {
Instruction &I = (Instruction&)GEPI;
for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
@ -112,6 +129,9 @@ bool LICM::runOnFunction(Function &) {
const std::vector<Loop*> &TopLevelLoops =
getAnalysis<LoopInfo>().getTopLevelLoops();
// Get our alias analysis information...
AA = &getAnalysis<AliasAnalysis>();
// Traverse loops in postorder, hoisting expressions out of the deepest loops
// first.
//
@ -198,6 +218,9 @@ void LICM::hoist(Instruction &Inst) {
string InstName = Inst.getName();
Inst.setName("");
if (isa<LoadInst>(Inst))
++NumHoistedLoads;
// The common case is that we have a pre-header. Generate special case code
// that is faster if that is the case.
//
@ -256,3 +279,13 @@ void LICM::hoist(Instruction &Inst) {
Changed = true;
}
// pointerInvalidatedByLoop - Return true if the body of this loop may store
// into the memory location pointed to by V.
//
bool LICM::pointerInvalidatedByLoop(Value *V) {
// Check to see if any of the basic blocks in CurLoop invalidate V.
for (unsigned i = 0, e = CurLoop->getBlocks().size(); i != e; ++i)
if (AA->canBasicBlockModify(*CurLoop->getBlocks()[i], V))
return true;
return false;
}