add support for phi translation and incorpation of new expression.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90782 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/PHITransAddr.cpp

@@ -16,6 +16,22 @@
 #include "llvm/Analysis/InstructionSimplify.h"
 using namespace llvm;
 
+static bool CanPHITrans(Instruction *Inst) {
+  if (isa<PHINode>(Inst) ||
+      isa<BitCastInst>(Inst) ||
+      isa<GetElementPtrInst>(Inst))
+    return true;
+  
+  if (Inst->getOpcode() == Instruction::And &&
+      isa<ConstantInt>(Inst->getOperand(1)))
+    return true;
+  
+  //   cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
+  //   if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst))
+  //     cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0);
+  return false;
+}
+
 /// IsPotentiallyPHITranslatable - If this needs PHI translation, return true
 /// if we have some hope of doing it.  This should be used as a filter to
 /// avoid calling PHITranslateValue in hopeless situations.
@@ -23,18 +39,7 @@ bool PHITransAddr::IsPotentiallyPHITranslatable() const {
   // If the input value is not an instruction, or if it is not defined in CurBB,
   // then we don't need to phi translate it.
   Instruction *Inst = dyn_cast<Instruction>(Addr);
-  if (isa<PHINode>(Inst) ||
+  return Inst == 0 || CanPHITrans(Inst);
-      isa<BitCastInst>(Inst) ||
-      isa<GetElementPtrInst>(Inst) ||
-      (Inst->getOpcode() == Instruction::And &&
-       isa<ConstantInt>(Inst->getOperand(1))))
-    return true;
-
-  //   cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
-  //   if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst))
-  //     cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0);
-
-  return false;
 }
 
 
@@ -44,18 +49,44 @@ Value *PHITransAddr::PHITranslateSubExpr(Value *V, BasicBlock *CurBB,
   Instruction *Inst = dyn_cast<Instruction>(V);
   if (Inst == 0) return V;
   
+  // If 'Inst' is defined in this block, it must be an input that needs to be
+  // phi translated or an intermediate expression that needs to be incorporated
+  // into the expression.
+  if (Inst->getParent() == CurBB) {
+    assert(std::count(InstInputs.begin(), InstInputs.end(), Inst) &&
+           "Not an input?");
+    
+    // If this is a PHI, go ahead and translate it.
+    if (PHINode *PN = dyn_cast<PHINode>(Inst))
+      return PN->getIncomingValueForBlock(PredBB);
+
+    
+    // If this is a non-phi value, and it is analyzable, we can incorporate it
+    // into the expression by making all instruction operands be inputs.
+    if (!CanPHITrans(Inst))
+      return 0;
+    
+    // Okay, we can incorporate it, this instruction is no longer an input.
+    InstInputs.erase(std::find(InstInputs.begin(), InstInputs.end(), Inst));
+    
+    // All instruction operands are now inputs (and of course, they may also be
+    // defined in this block, so they may need to be phi translated themselves.
+    for (unsigned i = 0, e = Inst->getNumOperands(); i != e; ++i)
+      if (Instruction *Op = dyn_cast<Instruction>(Inst->getOperand(i)))
+        InstInputs.push_back(Op);
+    
+  } else {
     // Determine whether 'Inst' is an input to our PHI translatable expression.
     bool isInput = std::count(InstInputs.begin(), InstInputs.end(), Inst);
     
-  // If 'Inst' is not defined in this block, it is either an input, or an
+    // If it is an input defined in a different block, then it remains an input.
-  // intermediate result.
-  if (Inst->getParent() != CurBB) {
-    // If it is an input, then it remains an input.
     if (isInput)
       return Inst;
+  }
 
-    // Otherwise, it must be an intermediate result.  See if its operands need
+  // Ok, it must be an intermediate result (either because it started that way
-    // to be phi translated, and if so, reconstruct it.
+  // or because we just incorporated it into the expression).  See if its
+  // operands need to be phi translated, and if so, reconstruct it.
   
   if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
     Value *PHIIn = PHITranslateSubExpr(BC->getOperand(0), CurBB, PredBB);
@@ -159,14 +190,6 @@ Value *PHITransAddr::PHITranslateSubExpr(Value *V, BasicBlock *CurBB,
   
   // Otherwise, we failed.
   return 0;
-  }
-
-  // Otherwise, it is defined in this block.  It must be an input and must be
-  // phi translated.
-  assert(isInput && "Instruction defined in block must be an input");
-  
-  
-  abort(); // unimplemented so far.
 }