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* Supoprt global constants

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* Remove support for local constant pools
* Eliminate constant pool merging method, which is no longer neccesary
* Disable invalid optimization (todo: fix it)

llvm-svn: 452
This commit is contained in:
Chris Lattner 2001-09-07 16:41:30 +00:00
parent 652b08d465
commit 6a211421bf
1 changed files with 13 additions and 55 deletions
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68
lib/Transforms/Scalar/ConstantProp.cpp
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@ -29,45 +29,6 @@
#include "llvm/iTerminators.h"
#include "llvm/iOther.h"
#include "llvm/ConstPoolVals.h"
#include "llvm/ConstantPool.h"
// Merge identical constant values in the constant pool.
//
// TODO: We can do better than this simplistic N^2 algorithm...
//
bool opt::DoConstantPoolMerging(Method *M) {
return DoConstantPoolMerging(M->getConstantPool());
}
bool opt::DoConstantPoolMerging(ConstantPool &CP) {
bool Modified = false;
for (ConstantPool::plane_iterator PI = CP.begin(); PI != CP.end(); ++PI) {
for (ConstantPool::PlaneType::iterator I = (*PI)->begin();
I != (*PI)->end(); ++I) {
ConstPoolVal *C = *I;
ConstantPool::PlaneType::iterator J = I;
for (++J; J != (*PI)->end(); ++J) {
if (C->equals(*J)) {
Modified = true;
// Okay we know that *I == *J. So now we need to make all uses of *I
// point to *J.
//
C->replaceAllUsesWith(*J);
(*PI)->remove(I); // Remove C from constant pool...
if (C->hasName() && !(*J)->hasName()) // The merged constant inherits
(*J)->setName(C->getName()); // the old name...
delete C; // Delete the constant itself.
break; // Break out of inner for loop
}
}
}
}
return Modified;
}
inline static bool
ConstantFoldUnaryInst(Method *M, Method::inst_iterator &DI,
@ -77,10 +38,6 @@ ConstantFoldUnaryInst(Method *M, Method::inst_iterator &DI,
if (!ReplaceWith) return false; // Nothing new to change...
// Add the new value to the constant pool...
M->getConstantPool().insert(ReplaceWith);
// Replaces all of the uses of a variable with uses of the constant.
Op->replaceAllUsesWith(ReplaceWith);
@ -88,7 +45,8 @@ ConstantFoldUnaryInst(Method *M, Method::inst_iterator &DI,
Op->getParent()->getInstList().remove(DI.getInstructionIterator());
// The new constant inherits the old name of the operator...
if (Op->hasName()) ReplaceWith->setName(Op->getName());
if (Op->hasName())
ReplaceWith->setName(Op->getName(), M->getSymbolTableSure());
// Delete the operator now...
delete Op;
@ -103,9 +61,6 @@ ConstantFoldBinaryInst(Method *M, Method::inst_iterator &DI,
opt::ConstantFoldBinaryInstruction(Op->getOpcode(), D1, D2);
if (!ReplaceWith) return false; // Nothing new to change...
// Add the new value to the constant pool...
M->getConstantPool().insert(ReplaceWith);
// Replaces all of the uses of a variable with uses of the constant.
Op->replaceAllUsesWith(ReplaceWith);
@ -113,7 +68,8 @@ ConstantFoldBinaryInst(Method *M, Method::inst_iterator &DI,
Op->getParent()->getInstList().remove(DI.getInstructionIterator());
// The new constant inherits the old name of the operator...
if (Op->hasName()) ReplaceWith->setName(Op->getName());
if (Op->hasName())
ReplaceWith->setName(Op->getName(), M->getSymbolTableSure());
// Delete the operator now...
delete Op;
@ -151,7 +107,12 @@ bool opt::ConstantFoldTerminator(TerminatorInst *T) {
// unconditional branch.
BI->setUnconditionalDest(Destination);
return true;
} else if (Dest2 == Dest1) { // Conditional branch to same location?
}
#if 0
// FIXME: TODO: This doesn't work if the destination has PHI nodes with
// different incoming values on each branch!
//
else if (Dest2 == Dest1) { // Conditional branch to same location?
// This branch matches something like this:
// br bool %cond, label %Dest, label %Dest
// and changes it into: br label %Dest
@ -164,6 +125,7 @@ bool opt::ConstantFoldTerminator(TerminatorInst *T) {
BI->setUnconditionalDest(Dest1);
return true;
}
#endif
}
return false;
}
@ -196,7 +158,8 @@ ConstantFoldInstruction(Method *M, Method::inst_iterator &II) {
PN->replaceAllUsesWith(V); // Replace all uses of this PHI
// Unlink from basic block
PN->getParent()->getInstList().remove(II.getInstructionIterator());
if (PN->hasName()) V->setName(PN->getName()); // Inherit PHINode name
if (PN->hasName()) // Inherit PHINode name
V->setName(PN->getName(), M->getSymbolTableSure());
delete PN; // Finally, delete the node...
return true;
}
@ -243,10 +206,5 @@ bool opt::DoConstantPropogation(Method *M) {
// Fold constants until we make no progress...
while (DoConstPropPass(M)) Modified = true;
// Merge identical constants last: this is important because we may have just
// introduced constants that already exist!
//
Modified |= DoConstantPoolMerging(M->getConstantPool());
return Modified;
}