From c68bace452dbad23794d4b3c47eeebc00d489cef Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Thu, 1 Apr 2004 20:28:45 +0000 Subject: [PATCH] Fix PR310 and TailDup/2004-04-01-DemoteRegToStack.llx git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12597 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Utils/DemoteRegToStack.cpp | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/lib/Transforms/Utils/DemoteRegToStack.cpp b/lib/Transforms/Utils/DemoteRegToStack.cpp index ea0cf83c369..a92a066469c 100644 --- a/lib/Transforms/Utils/DemoteRegToStack.cpp +++ b/lib/Transforms/Utils/DemoteRegToStack.cpp @@ -19,6 +19,7 @@ #include "llvm/Transforms/Utils/Local.h" #include "llvm/Function.h" #include "llvm/Instructions.h" +#include 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 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); }