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Implement LICM of calls in simple cases. This is sufficient to move around

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sin/cos/strlen calls and stuff.  This implements:
  LICM/call_sink_pure_function.ll
  LICM/call_sink_const_function.ll


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12415 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-03-15 04:11:30 +00:00
parent 65a88e83e3
commit 118dd0ce3d
1 changed files with 31 additions and 1 deletions
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32
lib/Transforms/Scalar/LICM.cpp
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@ -57,6 +57,7 @@ namespace {
Statistic<> NumSunk("licm", "Number of instructions sunk out of loop");
Statistic<> NumHoisted("licm", "Number of instructions hoisted out of loop");
Statistic<> NumMovedLoads("licm", "Number of load insts hoisted or sunk");
Statistic<> NumMovedCalls("licm", "Number of call insts hoisted or sunk");
Statistic<> NumPromoted("licm",
"Number of memory locations promoted to registers");
@ -360,9 +361,35 @@ bool LICM::canSinkOrHoistInst(Instruction &I) {
// Don't hoist loads which have may-aliased stores in loop.
return !pointerInvalidatedByLoop(LI->getOperand(0));
} else if (CallInst *CI = dyn_cast<CallInst>(&I)) {
// Handle obvious cases efficiently.
if (Function *Callee = CI->getCalledFunction()) {
if (AA->doesNotAccessMemory(Callee))
return true;
else if (AA->onlyReadsMemory(Callee)) {
// If this call only reads from memory and there are no writes to memory
// in the loop, we can hoist or sink the call as appropriate.
bool FoundMod = false;
for (AliasSetTracker::iterator I = CurAST->begin(), E = CurAST->end();
I != E; ++I) {
AliasSet &AS = *I;
if (!AS.isForwardingAliasSet() && AS.isMod()) {
FoundMod = true;
break;
}
}
if (!FoundMod) return true;
}
}
// FIXME: This should use mod/ref information to see if we can hoist or sink
// the call.
return false;
}
return isa<BinaryOperator>(I) || isa<ShiftInst>(I) || isa<CastInst>(I) ||
isa<SelectInst>(I) ||
isa<GetElementPtrInst>(I) || isa<VANextInst>(I) || isa<VAArgInst>(I);
}
@ -412,6 +439,7 @@ void LICM::sink(Instruction &I) {
const std::vector<BasicBlock*> &ExitBlocks = CurLoop->getExitBlocks();
if (isa<LoadInst>(I)) ++NumMovedLoads;
else if (isa<CallInst>(I)) ++NumMovedCalls;
++NumSunk;
Changed = true;
@ -541,6 +569,7 @@ void LICM::hoist(Instruction &I) {
Preheader->getInstList().insert(Preheader->getTerminator(), &I);
if (isa<LoadInst>(I)) ++NumMovedLoads;
else if (isa<CallInst>(I)) ++NumMovedCalls;
++NumHoisted;
Changed = true;
}
@ -679,7 +708,8 @@ void LICM::findPromotableValuesInLoop(
I != E; ++I) {
AliasSet &AS = *I;
// We can promote this alias set if it has a store, if it is a "Must" alias
// set, if the pointer is loop invariant, if if we are not eliminating any volatile loads or stores.
// set, if the pointer is loop invariant, if if we are not eliminating any
// volatile loads or stores.
if (!AS.isForwardingAliasSet() && AS.isMod() && AS.isMustAlias() &&
!AS.isVolatile() && isLoopInvariant(AS.begin()->first)) {
assert(AS.begin() != AS.end() &&