Have isel visit blocks in reverse postorder rather than an undefined order. This

[oota-llvm.git] / lib / CodeGen / SelectionDAG / SelectionDAGISel.cpp

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 279478f4a91d73094902eed054e99572e6308fcb..bbc62d8a91cc4d6d08505ef3c6b2820ea03c46bf 100644 (file)
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -49,6 +49,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/ADT/PostOrderIterator.h"
 #include "llvm/ADT/Statistic.h"
 #include <algorithm>
 using namespace llvm;
@@ -482,9 +483,7 @@ void SelectionDAGISel::ComputeLiveOutVRegInfo() {
 
     // Only install this information if it tells us something.
     if (NumSignBits != 1 || KnownZero != 0 || KnownOne != 0) {
-      DestReg -= TargetRegisterInfo::FirstVirtualRegister;
-      if (DestReg >= FuncInfo->LiveOutRegInfo.size())
-        FuncInfo->LiveOutRegInfo.resize(DestReg+1);
+      FuncInfo->LiveOutRegInfo.grow(DestReg);
       FunctionLoweringInfo::LiveOutInfo &LOI =
         FuncInfo->LiveOutRegInfo[DestReg];
       LOI.NumSignBits = NumSignBits;
@@ -773,8 +772,16 @@ bool SelectionDAGISel::TryToFoldFastISelLoad(const LoadInst *LI,
   assert(RI.getOperand().isUse() &&
          "The only use of the vreg must be a use, we haven't emitted the def!");
 
+  MachineInstr *User = &*RI;
+  
+  // Set the insertion point properly.  Folding the load can cause generation of
+  // other random instructions (like sign extends) for addressing modes, make
+  // sure they get inserted in a logical place before the new instruction.
+  FuncInfo->InsertPt = User;
+  FuncInfo->MBB = User->getParent();
+
   // Ask the target to try folding the load.
-  return FastIS->TryToFoldLoad(&*RI, RI.getOperandNo(), LI);
+  return FastIS->TryToFoldLoad(User, RI.getOperandNo(), LI);
 }
 
 #ifndef NDEBUG
@@ -826,8 +833,10 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
     FastIS = TLI.createFastISel(*FuncInfo);
 
   // Iterate over all basic blocks in the function.
-  for (Function::const_iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
-    const BasicBlock *LLVMBB = &*I;
+  ReversePostOrderTraversal<const Function*> RPOT(&Fn);
+  for (ReversePostOrderTraversal<const Function*>::rpo_iterator
+       I = RPOT.begin(), E = RPOT.end(); I != E; ++I) {
+    const BasicBlock *LLVMBB = *I;
 #ifndef NDEBUG
     CheckLineNumbers(LLVMBB);
 #endif
@@ -893,10 +902,8 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
             BeforeInst = llvm::prior(llvm::prior(BI));
           if (BeforeInst && isa<LoadInst>(BeforeInst) &&
               BeforeInst->hasOneUse() && *BeforeInst->use_begin() == Inst &&
-              TryToFoldFastISelLoad(cast<LoadInst>(BeforeInst), FastIS)) {
-            // If we succeeded, don't re-select the load.
-            --BI;
-          }
+              TryToFoldFastISelLoad(cast<LoadInst>(BeforeInst), FastIS))
+            --BI; // If we succeeded, don't re-select the load.
           continue;
         }
 
@@ -1137,7 +1144,7 @@ SelectionDAGISel::FinishBasicBlock() {
   // additional DAGs necessary.
   for (unsigned i = 0, e = SDB->SwitchCases.size(); i != e; ++i) {
     // Set the current basic block to the mbb we wish to insert the code into
-    MachineBasicBlock *ThisBB = FuncInfo->MBB = SDB->SwitchCases[i].ThisBB;
+    FuncInfo->MBB = SDB->SwitchCases[i].ThisBB;
     FuncInfo->InsertPt = FuncInfo->MBB->end();
 
     // Determine the unique successors.
@@ -1146,13 +1153,15 @@ SelectionDAGISel::FinishBasicBlock() {
     if (SDB->SwitchCases[i].TrueBB != SDB->SwitchCases[i].FalseBB)
       Succs.push_back(SDB->SwitchCases[i].FalseBB);
 
-    // Emit the code. Note that this could result in ThisBB being split, so
-    // we need to check for updates.
+    // Emit the code. Note that this could result in FuncInfo->MBB being split.
     SDB->visitSwitchCase(SDB->SwitchCases[i], FuncInfo->MBB);
     CurDAG->setRoot(SDB->getRoot());
     SDB->clear();
     CodeGenAndEmitDAG();
-    ThisBB = FuncInfo->MBB;
+
+    // Remember the last block, now that any splitting is done, for use in
+    // populating PHI nodes in successors.
+    MachineBasicBlock *ThisBB = FuncInfo->MBB;
 
     // Handle any PHI nodes in successors of this chunk, as if we were coming
     // from the original BB before switch expansion.  Note that PHI nodes can