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revert recent patch which is causing widespread breakage.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52415 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-06-17 17:06:43 +00:00
parent 1b088f3310
commit fc329f4fa1
1 changed files with 53 additions and 85 deletions
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138
lib/Transforms/IPO/IPConstantPropagation.cpp
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@ -21,7 +21,6 @@
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Compiler.h"
#include "llvm/ADT/Statistic.h"
@ -141,14 +140,9 @@ bool IPCP::PropagateConstantsIntoArguments(Function &F) {
}
// Check to see if this function returns one or more constants. If so, replace
// all callers that use those return values with the constant value. This will
// leave in the actual return values and instructions, but deadargelim will
// clean that up.
//
// Additionally if a function always returns one of its arguments directly,
// callers will be updated to use the value they pass in directly instead of
// using the return value.
// Check to see if this function returns a constant. If so, replace all callers
// that user the return value with the returned valued. If we can replace ALL
// callers,
bool IPCP::PropagateConstantReturn(Function &F) {
if (F.getReturnType() == Type::VoidTy)
return false; // No return value.
@ -162,65 +156,48 @@ bool IPCP::PropagateConstantReturn(Function &F) {
SmallVector<Value *,4> RetVals;
const StructType *STy = dyn_cast<StructType>(F.getReturnType());
if (STy)
for (unsigned i = 0, e = STy->getNumElements(); i < e; ++i)
RetVals.push_back(UndefValue::get(STy->getElementType(i)));
RetVals.assign(STy->getNumElements(), 0);
else
RetVals.push_back(UndefValue::get(F.getReturnType()));
RetVals.push_back(0);
unsigned NumNonConstant = 0;
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
// Return type does not match operand type, this is an old style multiple
// return
bool OldReturn = (F.getReturnType() != RI->getOperand(0)->getType());
assert(RetVals.size() == RI->getNumOperands() &&
"Invalid ReturnInst operands!");
for (unsigned i = 0, e = RetVals.size(); i != e; ++i) {
// Already found conflicting return values?
if (isa<UndefValue>(RI->getOperand(i)))
continue; // Ignore
Constant *C = dyn_cast<Constant>(RI->getOperand(i));
if (C == 0)
return false; // Does not return a constant.
Value *RV = RetVals[i];
if (!RV)
continue;
// Find the returned value
Value *V;
if (!STy || OldReturn)
V = RI->getOperand(i);
else
V = FindInsertedValue(RI->getOperand(0), i);
if (V) {
// Ignore undefs, we can change them into anything
if (isa<UndefValue>(V))
continue;
// Try to see if all the rets return the same constant or argument.
if (isa<Constant>(V) || isa<Argument>(V)) {
if (isa<UndefValue>(RV)) {
// No value found yet? Try the current one.
RetVals[i] = V;
continue;
}
// Returning the same value? Good.
if (RV == V)
continue;
}
}
// Different or no known return value? Don't propagate this return
// value.
RetVals[i] = 0;
// All values non constant? Stop looking.
if (++NumNonConstant == RetVals.size())
return false;
if (RV == 0)
RetVals[i] = C;
else if (RV != C)
return false; // Does not return the same constant.
}
}
// If we got here, the function returns at least one constant value. Loop
// over all users, replacing any uses of the return value with the returned
// constant.
if (STy) {
for (unsigned i = 0, e = RetVals.size(); i < e; ++i)
if (RetVals[i] == 0)
RetVals[i] = UndefValue::get(STy->getElementType(i));
} else {
assert(RetVals.size() == 1);
if (RetVals[0] == 0)
RetVals[0] = UndefValue::get(F.getReturnType());
}
// If we got here, the function returns a constant value. Loop over all
// users, replacing any uses of the return value with the returned constant.
bool ReplacedAllUsers = true;
bool MadeChange = false;
for (Value::use_iterator UI = F.use_begin(), E = F.use_end(); UI != E; ++UI) {
// Make sure this is an invoke or call and that the use is for the callee.
if (!(isa<InvokeInst>(*UI) || isa<CallInst>(*UI)) ||
UI.getOperandNo() != 0) {
ReplacedAllUsers = false;
continue;
}
@ -235,37 +212,28 @@ bool IPCP::PropagateConstantReturn(Function &F) {
continue;
}
for (Value::use_iterator I = Call->use_begin(), E = Call->use_end();
I != E;) {
Instruction *Ins = dyn_cast<Instruction>(*I);
// Increment now, so we can remove the use
++I;
// Not an instruction? Ignore
if (!Ins)
continue;
// Find the index of the retval to replace with
int index = -1;
if (GetResultInst *GR = dyn_cast<GetResultInst>(Ins))
index = GR->getIndex();
else if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Ins))
if (EV->hasIndices())
index = *EV->idx_begin();
// If this use uses a specific return value, and we have a replacement,
// replace it.
if (index != -1) {
Value *New = RetVals[index];
if (New) {
if (Argument *A = dyn_cast<Argument>(New))
// Was an argument returned? Then find the corresponding argument in
// the call instruction and use that. Add 1 to the argument number
// to skipp the first argument (the function itself).
New = Call->getOperand(A->getArgNo() + 1);
Ins->replaceAllUsesWith(New);
Ins->eraseFromParent();
while (!Call->use_empty()) {
GetResultInst *GR = cast<GetResultInst>(Call->use_back());
GR->replaceAllUsesWith(RetVals[GR->getIndex()]);
GR->eraseFromParent();
}
}
// If we replace all users with the returned constant, and there can be no
// other callers of the function, replace the constant being returned in the
// function with an undef value.
if (ReplacedAllUsers && F.hasInternalLinkage()) {
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
for (unsigned i = 0, e = RetVals.size(); i < e; ++i) {
Value *RetVal = RetVals[i];
if (isa<UndefValue>(RetVal))
continue;
Value *RV = UndefValue::get(RetVal->getType());
if (RI->getOperand(i) != RV) {
RI->setOperand(i, RV);
MadeChange = true;
}
}
}
}