[llvm-commits] [llvm] r43208 - in /llvm/trunk: include/llvm/Transforms/Utils/Local.h lib/Transforms/Scalar/Reg2Mem.cpp lib/Transforms/Utils/DemoteRegToStack.cpp
Anton Korobeynikov
asl at math.spbu.ru
Sun Oct 21 16:05:16 PDT 2007
Author: asl
Date: Sun Oct 21 18:05:16 2007
New Revision: 43208
URL: http://llvm.org/viewvc/llvm-project?rev=43208&view=rev
Log:
Reg2Mem cleanup and optimizations:
- enable phi instructions demotion to stack
- create alloca instructions in the entry block
Modified:
llvm/trunk/include/llvm/Transforms/Utils/Local.h
llvm/trunk/lib/Transforms/Scalar/Reg2Mem.cpp
llvm/trunk/lib/Transforms/Utils/DemoteRegToStack.cpp
Modified: llvm/trunk/include/llvm/Transforms/Utils/Local.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/Local.h?rev=43208&r1=43207&r2=43208&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/Local.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/Local.h Sun Oct 21 18:05:16 2007
@@ -78,12 +78,13 @@
/// invalidating the SSA information for the value. It returns the pointer to
/// the alloca inserted to create a stack slot for X.
///
-AllocaInst *DemoteRegToStack(Instruction &X, bool VolatileLoads = false);
+AllocaInst *DemoteRegToStack(Instruction &X, bool VolatileLoads = false,
+ Instruction *AllocaPoint = NULL);
/// DemotePHIToStack - This function takes a virtual register computed by a phi
/// node and replaces it with a slot in the stack frame, allocated via alloca.
/// The phi node is deleted and it returns the pointer to the alloca inserted.
-AllocaInst *DemotePHIToStack(PHINode *P);
+AllocaInst *DemotePHIToStack(PHINode *P, Instruction *AllocaPoint = NULL);
} // End llvm namespace
Modified: llvm/trunk/lib/Transforms/Scalar/Reg2Mem.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/Reg2Mem.cpp?rev=43208&r1=43207&r2=43208&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/Reg2Mem.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/Reg2Mem.cpp Sun Oct 21 18:05:16 2007
@@ -26,10 +26,12 @@
#include "llvm/Instructions.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Compiler.h"
+#include "llvm/Support/CFG.h"
#include <list>
using namespace llvm;
-STATISTIC(NumDemoted, "Number of registers demoted");
+STATISTIC(NumRegsDemoted, "Number of registers demoted");
+STATISTIC(NumPhisDemoted, "Number of phi-nodes demoted");
namespace {
struct VISIBILITY_HIDDEN RegToMem : public FunctionPass {
@@ -43,8 +45,8 @@
bool valueEscapes(Instruction* i) {
BasicBlock* bb = i->getParent();
- for(Value::use_iterator ii = i->use_begin(), ie = i->use_end();
- ii != ie; ++ii)
+ for (Value::use_iterator ii = i->use_begin(), ie = i->use_end();
+ ii != ie; ++ii)
if (cast<Instruction>(*ii)->getParent() != bb ||
isa<PHINode>(*ii))
return true;
@@ -53,26 +55,57 @@
virtual bool runOnFunction(Function &F) {
if (!F.isDeclaration()) {
- //give us a clean block
- BasicBlock* bbold = &F.getEntryBlock();
- BasicBlock* bbnew = new BasicBlock("allocablock", &F,
- &F.getEntryBlock());
- new BranchInst(bbold, bbnew);
+ // Insert all new allocas into entry block.
+ BasicBlock* BBEntry = &F.getEntryBlock();
+ assert(pred_begin(BBEntry) == pred_end(BBEntry) &&
+ "Entry block to function must not have predecessors!");
+
+ // Find first non-alloca instruction and create insertion point. This is
+ // safe if block is well-formed: it always have terminator, otherwise
+ // we'll get and assertion.
+ BasicBlock::iterator I = BBEntry->begin();
+ while (isa<AllocaInst>(I)) ++I;
+
+ CastInst *AllocaInsertionPoint =
+ CastInst::create(Instruction::BitCast,
+ Constant::getNullValue(Type::Int32Ty), Type::Int32Ty,
+ "reg2mem alloca point", I);
- //find the instructions
+ // Find the escaped instructions. But don't create stack slots for
+ // allocas in entry block.
std::list<Instruction*> worklist;
for (Function::iterator ibb = F.begin(), ibe = F.end();
ibb != ibe; ++ibb)
for (BasicBlock::iterator iib = ibb->begin(), iie = ibb->end();
iib != iie; ++iib) {
- if(valueEscapes(iib))
+ if (!(isa<AllocaInst>(iib) && iib->getParent() == BBEntry) &&
+ valueEscapes(iib)) {
worklist.push_front(&*iib);
+ }
}
- //demote escaped instructions
- NumDemoted += worklist.size();
+
+ // Demote escaped instructions
+ NumRegsDemoted += worklist.size();
for (std::list<Instruction*>::iterator ilb = worklist.begin(),
ile = worklist.end(); ilb != ile; ++ilb)
- DemoteRegToStack(**ilb, false);
+ DemoteRegToStack(**ilb, false, AllocaInsertionPoint);
+
+ worklist.clear();
+
+ // Find all phi's
+ for (Function::iterator ibb = F.begin(), ibe = F.end();
+ ibb != ibe; ++ibb)
+ for (BasicBlock::iterator iib = ibb->begin(), iie = ibb->end();
+ iib != iie; ++iib)
+ if (isa<PHINode>(iib))
+ worklist.push_front(&*iib);
+
+ // Demote phi nodes
+ NumPhisDemoted += worklist.size();
+ for (std::list<Instruction*>::iterator ilb = worklist.begin(),
+ ile = worklist.end(); ilb != ile; ++ilb)
+ DemotePHIToStack(cast<PHINode>(*ilb), AllocaInsertionPoint);
+
return true;
}
return false;
Modified: llvm/trunk/lib/Transforms/Utils/DemoteRegToStack.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/DemoteRegToStack.cpp?rev=43208&r1=43207&r2=43208&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/DemoteRegToStack.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/DemoteRegToStack.cpp Sun Oct 21 18:05:16 2007
@@ -29,14 +29,23 @@
/// invalidating the SSA information for the value. It returns the pointer to
/// the alloca inserted to create a stack slot for I.
///
-AllocaInst* llvm::DemoteRegToStack(Instruction &I, bool VolatileLoads) {
- if (I.use_empty()) return 0; // nothing to do!
-
+AllocaInst* llvm::DemoteRegToStack(Instruction &I, bool VolatileLoads,
+ Instruction *AllocaPoint) {
+ if (I.use_empty()) {
+ I.eraseFromParent();
+ return 0;
+ }
+
// Create a stack slot to hold the value.
- Function *F = I.getParent()->getParent();
- AllocaInst *Slot = new AllocaInst(I.getType(), 0, I.getName(),
- F->getEntryBlock().begin());
-
+ AllocaInst *Slot;
+ if (AllocaPoint) {
+ Slot = new AllocaInst(I.getType(), 0, I.getName()+".reg2mem", AllocaPoint);
+ } else {
+ Function *F = I.getParent()->getParent();
+ Slot = new AllocaInst(I.getType(), 0, I.getName()+".reg2mem",
+ F->getEntryBlock().begin());
+ }
+
// Change all of the users of the instruction to read from the stack slot
// instead.
while (!I.use_empty()) {
@@ -98,16 +107,21 @@
/// DemotePHIToStack - This function takes a virtual register computed by a phi
/// node and replaces it with a slot in the stack frame, allocated via alloca.
/// The phi node is deleted and it returns the pointer to the alloca inserted.
-AllocaInst* llvm::DemotePHIToStack(PHINode *P) {
+AllocaInst* llvm::DemotePHIToStack(PHINode *P, Instruction *AllocaPoint) {
if (P->use_empty()) {
P->eraseFromParent();
return 0;
}
-
+
// Create a stack slot to hold the value.
- Function *F = P->getParent()->getParent();
- AllocaInst *Slot = new AllocaInst(P->getType(), 0, P->getName(),
- F->getEntryBlock().begin());
+ AllocaInst *Slot;
+ if (AllocaPoint) {
+ Slot = new AllocaInst(P->getType(), 0, P->getName()+".reg2mem", AllocaPoint);
+ } else {
+ Function *F = P->getParent()->getParent();
+ Slot = new AllocaInst(P->getType(), 0, P->getName()+".reg2mem",
+ F->getEntryBlock().begin());
+ }
// Iterate over each operand, insert store in each predecessor.
for (unsigned i = 0, e = P->getNumIncomingValues(); i < e; ++i) {
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