Implement review feedback for the ConstantBool->ConstantInt merge. Chris

[oota-llvm.git] / lib / Transforms / Scalar / CondPropagate.cpp

diff --git a/lib/Transforms/Scalar/CondPropagate.cpp b/lib/Transforms/Scalar/CondPropagate.cpp
index 138be522ee1092ceb401913de9c2fa752e42b38b..253535e3a5e1c3e7398fe4d489eaaa11a0a0aa24 100644 (file)
--- a/lib/Transforms/Scalar/CondPropagate.cpp
+++ b/lib/Transforms/Scalar/CondPropagate.cpp
@@ -1,10 +1,10 @@
 //===-- CondPropagate.cpp - Propagate Conditional Expressions -------------===//
-// 
+//
 //                     The LLVM Compiler Infrastructure
 //
 // This file was developed by the LLVM research group and is distributed under
 // the University of Illinois Open Source License. See LICENSE.TXT for details.
-// 
+//
 //===----------------------------------------------------------------------===//
 //
 // This pass propagates information about conditional expressions through the
@@ -22,15 +22,13 @@
 #include "llvm/Type.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Statistic.h"
-#include <iostream>
+#include "llvm/Support/Streams.h"
 using namespace llvm;
 
-namespace {
-  Statistic<>
-  NumBrThread("condprop", "Number of CFG edges threaded through branches");
-  Statistic<>
-  NumSwThread("condprop", "Number of CFG edges threaded through switches");
+STATISTIC(NumBrThread, "Number of CFG edges threaded through branches");
+STATISTIC(NumSwThread, "Number of CFG edges threaded through switches");
 
+namespace {
   struct CondProp : public FunctionPass {
     virtual bool runOnFunction(Function &F);
 
@@ -46,7 +44,7 @@ namespace {
     void SimplifyPredecessors(SwitchInst *SI);
     void RevectorBlockTo(BasicBlock *FromBB, BasicBlock *ToBB);
   };
-  RegisterOpt<CondProp> X("condprop", "Conditional Propagation");
+  RegisterPass<CondProp> X("condprop", "Conditional Propagation");
 }
 
 FunctionPass *llvm::createCondPropagationPass() {
@@ -73,24 +71,13 @@ void CondProp::SimplifyBlock(BasicBlock *BB) {
     if (BI->isConditional() && isa<PHINode>(BI->getCondition()) &&
         cast<PHINode>(BI->getCondition())->getParent() == BB)
       SimplifyPredecessors(BI);
-    
+
   } else if (SwitchInst *SI = dyn_cast<SwitchInst>(BB->getTerminator())) {
     if (isa<PHINode>(SI->getCondition()) &&
         cast<PHINode>(SI->getCondition())->getParent() == BB)
       SimplifyPredecessors(SI);
   }
 
-  // See if we can fold any PHI nodes in this block now.
-  // FIXME: This would not be required if removePredecessor did this for us!!
-  PHINode *PN;
-  for (BasicBlock::iterator I = BB->begin(); PN = dyn_cast<PHINode>(I++); )
-    if (Value *PNV = hasConstantValue(PN))
-      if (!isa<Instruction>(PNV)) {
-        PN->replaceAllUsesWith(PNV);
-        PN->eraseFromParent();
-        MadeChange = true;
-      }
-
   // If possible, simplify the terminator of this block.
   if (ConstantFoldTerminator(BB))
     MadeChange = true;
@@ -98,8 +85,18 @@ void CondProp::SimplifyBlock(BasicBlock *BB) {
   // If this block ends with an unconditional branch and the only successor has
   // only this block as a predecessor, merge the two blocks together.
   if (BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator()))
-    if (BI->isUnconditional() && BI->getSuccessor(0)->getSinglePredecessor()) {
+    if (BI->isUnconditional() && BI->getSuccessor(0)->getSinglePredecessor() &&
+        BB != BI->getSuccessor(0)) {
       BasicBlock *Succ = BI->getSuccessor(0);
+      
+      // If Succ has any PHI nodes, they are all single-entry PHI's.
+      while (PHINode *PN = dyn_cast<PHINode>(Succ->begin())) {
+        assert(PN->getNumIncomingValues() == 1 &&
+               "PHI doesn't match parent block");
+        PN->replaceAllUsesWith(PN->getIncomingValue(0));
+        PN->eraseFromParent();
+      }
+      
       // Remove BI.
       BI->eraseFromParent();
 
@@ -136,12 +133,13 @@ void CondProp::SimplifyPredecessors(BranchInst *BI) {
   // constants.  Walk from the end to remove operands from the end when
   // possible, and to avoid invalidating "i".
   for (unsigned i = PN->getNumIncomingValues(); i != 0; --i)
-    if (ConstantBool *CB = dyn_cast<ConstantBool>(PN->getIncomingValue(i-1))) {
+    if (ConstantInt *CB = dyn_cast<ConstantInt>(PN->getIncomingValue(i-1))) {
+      if (CB->getType() != Type::Int1Ty) continue;
       // If we have a constant, forward the edge from its current to its
       // ultimate destination.
       bool PHIGone = PN->getNumIncomingValues() == 2;
       RevectorBlockTo(PN->getIncomingBlock(i-1),
-                      BI->getSuccessor(CB->getValue() == 0));
+                      BI->getSuccessor(CB->getZExtValue() == 0));
       ++NumBrThread;
 
       // If there were two predecessors before this simplification, the PHI node
@@ -197,11 +195,14 @@ void CondProp::RevectorBlockTo(BasicBlock *FromBB, BasicBlock *ToBB) {
   // Get the old block we are threading through.
   BasicBlock *OldSucc = FromBr->getSuccessor(0);
 
-  // ToBB should not have any PHI nodes in it to update, because OldSucc had
-  // multiple successors.  If OldSucc had multiple successor and ToBB had
-  // multiple predecessors, the edge between them would be critical, which we
-  // already took care of.
-  assert(!isa<PHINode>(ToBB->begin()) && "Critical Edge Found!");
+  // OldSucc had multiple successors. If ToBB has multiple predecessors, then 
+  // the edge between them would be critical, which we already took care of.
+  // If ToBB has single operand PHI node then take care of it here.
+  while (PHINode *PN = dyn_cast<PHINode>(ToBB->begin())) {
+    assert(PN->getNumIncomingValues() == 1 && "Critical Edge Found!");    
+    PN->replaceAllUsesWith(PN->getIncomingValue(0));
+    PN->eraseFromParent();
+  }
 
   // Update PHI nodes in OldSucc to know that FromBB no longer branches to it.
   OldSucc->removePredecessor(FromBB);