X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FMachineSink.cpp;h=0e18fa742f5b327cc61dfe170b0d5cbf9ac74552;hb=e7800be8f08da88e9916020bb770e22c0d98625b;hp=b4e72fed28db8c793b6a627b417ad87a27d56315;hpb=844731a7f1909f55935e3514c9e713a62d67662e;p=oota-llvm.git

diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp
index b4e72fed28d..0e18fa742f5 100644
--- a/lib/CodeGen/MachineSink.cpp
+++ b/lib/CodeGen/MachineSink.cpp
@@ -18,7 +18,6 @@
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetMachine.h"
-#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
@@ -36,7 +35,7 @@ namespace {
 
   public:
     static char ID; // Pass identification
-    MachineSinking() : MachineFunctionPass((intptr_t)&ID) {}
+    MachineSinking() : MachineFunctionPass(&ID) {}
     
     virtual bool runOnMachineFunction(MachineFunction &MF);
     
@@ -112,20 +111,29 @@ bool MachineSinking::runOnMachineFunction(MachineFunction &MF) {
 }
 
 bool MachineSinking::ProcessBlock(MachineBasicBlock &MBB) {
-  bool MadeChange = false;
-  
   // Can't sink anything out of a block that has less than two successors.
-  if (MBB.succ_size() <= 1) return false;
-  
+  if (MBB.succ_size() <= 1 || MBB.empty()) return false;
+
+  bool MadeChange = false;
+
   // Walk the basic block bottom-up.  Remember if we saw a store.
-  bool SawStore = false;
-  for (MachineBasicBlock::iterator I = MBB.end(); I != MBB.begin(); ){
-    MachineBasicBlock::iterator LastIt = I;
-    if (SinkInstruction(--I, SawStore)) {
-      I = LastIt;
-      ++NumSunk;
-    }
-  }
+  MachineBasicBlock::iterator I = MBB.end();
+  --I;
+  bool ProcessedBegin, SawStore = false;
+  do {
+    MachineInstr *MI = I;  // The instruction to sink.
+    
+    // Predecrement I (if it's not begin) so that it isn't invalidated by
+    // sinking.
+    ProcessedBegin = I == MBB.begin();
+    if (!ProcessedBegin)
+      --I;
+    
+    if (SinkInstruction(MI, SawStore))
+      ++NumSunk, MadeChange = true;
+    
+    // If we just processed the first instruction in the block, we're done.
+  } while (!ProcessedBegin);
   
   return MadeChange;
 }
@@ -168,6 +176,10 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
     } else {
       // Virtual register uses are always safe to sink.
       if (MO.isUse()) continue;
+
+      // If it's not safe to move defs of the register class, then abort.
+      if (!TII->isSafeToMoveRegClassDefs(RegInfo->getRegClass(Reg)))
+        return false;
       
       // FIXME: This picks a successor to sink into based on having one
       // successor that dominates all the uses.  However, there are cases where
@@ -209,6 +221,16 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
   // If there are no outputs, it must have side-effects.
   if (SuccToSinkTo == 0)
     return false;
+
+  // It's not safe to sink instructions to EH landing pad. Control flow into
+  // landing pad is implicitly defined.
+  if (SuccToSinkTo->isLandingPad())
+    return false;
+  
+  // If is not possible to sink an instruction into its own block.  This can
+  // happen with loops.
+  if (MI->getParent() == SuccToSinkTo)
+    return false;
   
   DEBUG(cerr << "Sink instr " << *MI);
   DEBUG(cerr << "to block " << *SuccToSinkTo);