[llvm-commits] [llvm] r40805 - /llvm/trunk/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
Chris Lattner
sabre at nondot.org
Fri Aug 3 18:41:18 PDT 2007
Author: lattner
Date: Fri Aug 3 20:41:18 2007
New Revision: 40805
URL: http://llvm.org/viewvc/llvm-project?rev=40805&view=rev
Log:
refactor some code to shrink PromoteMem2Reg::run a bit
Modified:
llvm/trunk/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
Modified: llvm/trunk/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/PromoteMemoryToRegister.cpp?rev=40805&r1=40804&r2=40805&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/PromoteMemoryToRegister.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/PromoteMemoryToRegister.cpp Fri Aug 3 20:41:18 2007
@@ -16,6 +16,7 @@
//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "mem2reg"
#include "llvm/Transforms/Utils/PromoteMemToReg.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
@@ -26,12 +27,17 @@
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Compiler.h"
#include <algorithm>
using namespace llvm;
+STATISTIC(NumLocalPromoted, "Number of alloca's promoted within one block");
+STATISTIC(NumSingleStore, "Number of alloca's promoted with a single store");
+STATISTIC(NumDeadAlloca, "Number of dead alloca's removed");
+
// Provide DenseMapKeyInfo for all pointers.
namespace llvm {
template<>
@@ -153,6 +159,12 @@
}
private:
+ void RemoveFromAllocasList(unsigned &AllocaIdx) {
+ Allocas[AllocaIdx] = Allocas.back();
+ Allocas.pop_back();
+ --AllocaIdx;
+ }
+
void MarkDominatingPHILive(BasicBlock *BB, unsigned AllocaNum,
SmallPtrSet<PHINode*, 16> &DeadPHINodes);
bool PromoteLocallyUsedAlloca(BasicBlock *BB, AllocaInst *AI);
@@ -165,6 +177,58 @@
bool QueuePhiNode(BasicBlock *BB, unsigned AllocaIdx, unsigned &Version,
SmallPtrSet<PHINode*, 16> &InsertedPHINodes);
};
+
+ struct AllocaInfo {
+ std::vector<BasicBlock*> DefiningBlocks;
+ std::vector<BasicBlock*> UsingBlocks;
+
+ StoreInst *OnlyStore;
+ BasicBlock *OnlyBlock;
+ bool OnlyUsedInOneBlock;
+
+ Value *AllocaPointerVal;
+
+ void clear() {
+ DefiningBlocks.clear();
+ UsingBlocks.clear();
+ OnlyStore = 0;
+ OnlyBlock = 0;
+ OnlyUsedInOneBlock = true;
+ AllocaPointerVal = 0;
+ }
+
+ /// AnalyzeAlloca - Scan the uses of the specified alloca, filling in our
+ /// ivars.
+ void AnalyzeAlloca(AllocaInst *AI) {
+ clear();
+
+ // As we scan the uses of the alloca instruction, keep track of stores,
+ // and decide whether all of the loads and stores to the alloca are within
+ // the same basic block.
+ for (Value::use_iterator U = AI->use_begin(), E = AI->use_end();
+ U != E; ++U){
+ Instruction *User = cast<Instruction>(*U);
+ if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
+ // Remember the basic blocks which define new values for the alloca
+ DefiningBlocks.push_back(SI->getParent());
+ AllocaPointerVal = SI->getOperand(0);
+ OnlyStore = SI;
+ } else {
+ LoadInst *LI = cast<LoadInst>(User);
+ // Otherwise it must be a load instruction, keep track of variable reads
+ UsingBlocks.push_back(LI->getParent());
+ AllocaPointerVal = LI;
+ }
+
+ if (OnlyUsedInOneBlock) {
+ if (OnlyBlock == 0)
+ OnlyBlock = User->getParent();
+ else if (OnlyBlock != User->getParent())
+ OnlyUsedInOneBlock = false;
+ }
+ }
+ }
+ };
} // end of anonymous namespace
@@ -180,6 +244,8 @@
if (AST) PointerAllocaValues.resize(Allocas.size());
+ AllocaInfo Info;
+
for (unsigned AllocaNum = 0; AllocaNum != Allocas.size(); ++AllocaNum) {
AllocaInst *AI = Allocas[AllocaNum];
@@ -194,80 +260,46 @@
AI->eraseFromParent();
// Remove the alloca from the Allocas list, since it has been processed
- Allocas[AllocaNum] = Allocas.back();
- Allocas.pop_back();
- --AllocaNum;
+ RemoveFromAllocasList(AllocaNum);
+ ++NumDeadAlloca;
continue;
}
-
+
// Calculate the set of read and write-locations for each alloca. This is
// analogous to finding the 'uses' and 'definitions' of each variable.
- std::vector<BasicBlock*> DefiningBlocks;
- std::vector<BasicBlock*> UsingBlocks;
-
- StoreInst *OnlyStore = 0;
- BasicBlock *OnlyBlock = 0;
- bool OnlyUsedInOneBlock = true;
-
- // As we scan the uses of the alloca instruction, keep track of stores, and
- // decide whether all of the loads and stores to the alloca are within the
- // same basic block.
- Value *AllocaPointerVal = 0;
- for (Value::use_iterator U =AI->use_begin(), E = AI->use_end(); U != E;++U){
- Instruction *User = cast<Instruction>(*U);
- if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
- // Remember the basic blocks which define new values for the alloca
- DefiningBlocks.push_back(SI->getParent());
- AllocaPointerVal = SI->getOperand(0);
- OnlyStore = SI;
- } else {
- LoadInst *LI = cast<LoadInst>(User);
- // Otherwise it must be a load instruction, keep track of variable reads
- UsingBlocks.push_back(LI->getParent());
- AllocaPointerVal = LI;
- }
-
- if (OnlyUsedInOneBlock) {
- if (OnlyBlock == 0)
- OnlyBlock = User->getParent();
- else if (OnlyBlock != User->getParent())
- OnlyUsedInOneBlock = false;
- }
- }
+ Info.AnalyzeAlloca(AI);
// If the alloca is only read and written in one basic block, just perform a
// linear sweep over the block to eliminate it.
- if (OnlyUsedInOneBlock) {
- LocallyUsedAllocas[OnlyBlock].push_back(AI);
+ if (Info.OnlyUsedInOneBlock) {
+ LocallyUsedAllocas[Info.OnlyBlock].push_back(AI);
// Remove the alloca from the Allocas list, since it will be processed.
- Allocas[AllocaNum] = Allocas.back();
- Allocas.pop_back();
- --AllocaNum;
+ RemoveFromAllocasList(AllocaNum);
continue;
}
// If there is only a single store to this value, replace any loads of
// it that are directly dominated by the definition with the value stored.
- if (DefiningBlocks.size() == 1) {
+ if (Info.DefiningBlocks.size() == 1) {
// Be aware of loads before the store.
std::set<BasicBlock*> ProcessedBlocks;
- for (unsigned i = 0, e = UsingBlocks.size(); i != e; ++i)
+ for (unsigned i = 0, e = Info.UsingBlocks.size(); i != e; ++i)
// If the store dominates the block and if we haven't processed it yet,
// do so now.
- if (dominates(OnlyStore->getParent(), UsingBlocks[i]))
- if (ProcessedBlocks.insert(UsingBlocks[i]).second) {
- BasicBlock *UseBlock = UsingBlocks[i];
+ if (dominates(Info.OnlyStore->getParent(), Info.UsingBlocks[i]))
+ if (ProcessedBlocks.insert(Info.UsingBlocks[i]).second) {
+ BasicBlock *UseBlock = Info.UsingBlocks[i];
// If the use and store are in the same block, do a quick scan to
// verify that there are no uses before the store.
- if (UseBlock == OnlyStore->getParent()) {
+ if (UseBlock == Info.OnlyStore->getParent()) {
BasicBlock::iterator I = UseBlock->begin();
- for (; &*I != OnlyStore; ++I) { // scan block for store.
+ for (; &*I != Info.OnlyStore; ++I) { // scan block for store.
if (isa<LoadInst>(I) && I->getOperand(0) == AI)
break;
}
- if (&*I != OnlyStore) break; // Do not handle this case.
+ if (&*I != Info.OnlyStore) break; // Do not handle this case.
}
// Otherwise, if this is a different block or if all uses happen
@@ -277,7 +309,7 @@
I != E; ) {
if (LoadInst *LI = dyn_cast<LoadInst>(I++)) {
if (LI->getOperand(0) == AI) {
- LI->replaceAllUsesWith(OnlyStore->getOperand(0));
+ LI->replaceAllUsesWith(Info.OnlyStore->getOperand(0));
if (AST && isa<PointerType>(LI->getType()))
AST->deleteValue(LI);
LI->eraseFromParent();
@@ -286,23 +318,22 @@
}
// Finally, remove this block from the UsingBlock set.
- UsingBlocks[i] = UsingBlocks.back();
+ Info.UsingBlocks[i] = Info.UsingBlocks.back();
--i; --e;
}
// Finally, after the scan, check to see if the store is all that is left.
- if (UsingBlocks.empty()) {
+ if (Info.UsingBlocks.empty()) {
+ ++NumSingleStore;
// The alloca has been processed, move on.
- Allocas[AllocaNum] = Allocas.back();
- Allocas.pop_back();
- --AllocaNum;
+ RemoveFromAllocasList(AllocaNum);
continue;
}
}
if (AST)
- PointerAllocaValues[AllocaNum] = AllocaPointerVal;
+ PointerAllocaValues[AllocaNum] = Info.AllocaPointerVal;
// If we haven't computed a numbering for the BB's in the function, do so
// now.
@@ -318,9 +349,9 @@
unsigned CurrentVersion = 0;
SmallPtrSet<PHINode*, 16> InsertedPHINodes;
std::vector<std::pair<unsigned, BasicBlock*> > DFBlocks;
- while (!DefiningBlocks.empty()) {
- BasicBlock *BB = DefiningBlocks.back();
- DefiningBlocks.pop_back();
+ while (!Info.DefiningBlocks.empty()) {
+ BasicBlock *BB = Info.DefiningBlocks.back();
+ Info.DefiningBlocks.pop_back();
// Look up the DF for this write, add it to PhiNodes
DominanceFrontier::const_iterator it = DF.find(BB);
@@ -342,7 +373,7 @@
for (unsigned i = 0, e = DFBlocks.size(); i != e; ++i) {
BasicBlock *BB = DFBlocks[i].second;
if (QueuePhiNode(BB, AllocaNum, CurrentVersion, InsertedPHINodes))
- DefiningBlocks.push_back(BB);
+ Info.DefiningBlocks.push_back(BB);
}
DFBlocks.clear();
}
@@ -355,9 +386,9 @@
// marked alive because of loads which are dominated by stores, but there
// will be no unmarked PHI nodes which are actually used.
//
- for (unsigned i = 0, e = UsingBlocks.size(); i != e; ++i)
- MarkDominatingPHILive(UsingBlocks[i], AllocaNum, InsertedPHINodes);
- UsingBlocks.clear();
+ for (unsigned i = 0, e = Info.UsingBlocks.size(); i != e; ++i)
+ MarkDominatingPHILive(Info.UsingBlocks[i], AllocaNum, InsertedPHINodes);
+ Info.UsingBlocks.clear();
// If there are any PHI nodes which are now known to be dead, remove them!
for (SmallPtrSet<PHINode*, 16>::iterator I = InsertedPHINodes.begin(),
@@ -623,6 +654,8 @@
assert(AI->use_empty() && "Uses of alloca from more than one BB??");
if (AST) AST->deleteValue(AI);
AI->getParent()->getInstList().erase(AI);
+
+ ++NumLocalPromoted;
return false;
}
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