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Fix PR310 and TailDup/2004-04-01-DemoteRegToStack.llx

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12597 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-04-01 20:28:45 +00:00
parent 8b8ff16dba
commit c68bace452
1 changed files with 12 additions and 5 deletions
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17
lib/Transforms/Utils/DemoteRegToStack.cpp
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@ -19,6 +19,7 @@
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include <map>
using namespace llvm;
/// DemoteRegToStack - This function takes a virtual register computed by an
@ -45,13 +46,19 @@ AllocaInst* llvm::DemoteRegToStack(Instruction &I) {
// to the incoming value.
//
// Note that if there are multiple edges from a basic block to this PHI
// node that we'll insert multiple loads. Since DemoteRegToStack requires
// a mem2reg pass after it (to produce reasonable code), we don't care.
// node that we cannot multiple loads. The problem is that the resultant
// PHI node will have multiple values (from each load) coming in from the
// same block, which is illegal SSA form. For this reason, we keep track
// and reuse loads we insert.
std::map<BasicBlock*, Value*> Loads;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (PN->getIncomingValue(i) == &I) {
// Insert the load into the predecessor block
Value *V = new LoadInst(Slot, I.getName()+".reload",
PN->getIncomingBlock(i)->getTerminator());
Value *&V = Loads[PN->getIncomingBlock(i)];
if (V == 0) {
// Insert the load into the predecessor block
V = new LoadInst(Slot, I.getName()+".reload",
PN->getIncomingBlock(i)->getTerminator());
}
PN->setIncomingValue(i, V);
}