Update LLVM sources to r73879.

3 files changed, 73 insertions, 3 deletions

diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index 94483b8..c7fff54 100644
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -14,6 +14,7 @@
 
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Constants.h"
+#include "llvm/GlobalAlias.h"
 #include "llvm/GlobalVariable.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/Instructions.h"
@@ -28,6 +29,50 @@
 using namespace llvm;
 
 //===----------------------------------------------------------------------===//
+//  Local analysis.
+//
+
+/// isSafeToLoadUnconditionally - Return true if we know that executing a load
+/// from this value cannot trap.  If it is not obviously safe to load from the
+/// specified pointer, we do a quick local scan of the basic block containing
+/// ScanFrom, to determine if the address is already accessed.
+bool llvm::isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
+  // If it is an alloca it is always safe to load from.
+  if (isa<AllocaInst>(V)) return true;
+
+  // If it is a global variable it is mostly safe to load from.
+  if (const GlobalValue *GV = dyn_cast<GlobalVariable>(V))
+    // Don't try to evaluate aliases.  External weak GV can be null.
+    return !isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage();
+
+  // Otherwise, be a little bit agressive by scanning the local block where we
+  // want to check to see if the pointer is already being loaded or stored
+  // from/to.  If so, the previous load or store would have already trapped,
+  // so there is no harm doing an extra load (also, CSE will later eliminate
+  // the load entirely).
+  BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
+
+  while (BBI != E) {
+    --BBI;
+
+    // If we see a free or a call which may write to memory (i.e. which might do
+    // a free) the pointer could be marked invalid.
+    if (isa<FreeInst>(BBI) || 
+        (isa<CallInst>(BBI) && BBI->mayWriteToMemory() &&
+         !isa<DbgInfoIntrinsic>(BBI)))
+      return false;
+
+    if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
+      if (LI->getOperand(0) == V) return true;
+    } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
+      if (SI->getOperand(1) == V) return true;
+    }
+  }
+  return false;
+}
+
+
+//===----------------------------------------------------------------------===//
 //  Local constant propagation.
 //
 
diff --git a/lib/Transforms/Utils/LowerAllocations.cpp b/lib/Transforms/Utils/LowerAllocations.cpp
index 3249895..9af47f5 100644
--- a/lib/Transforms/Utils/LowerAllocations.cpp
+++ b/lib/Transforms/Utils/LowerAllocations.cpp
@@ -112,7 +112,7 @@ bool LowerAllocations::runOnBasicBlock(BasicBlock &BB) {
     if (MallocInst *MI = dyn_cast<MallocInst>(I)) {
       const Type *AllocTy = MI->getType()->getElementType();
 
-      // malloc(type) becomes sbyte *malloc(size)
+      // malloc(type) becomes i8 *malloc(size)
       Value *MallocArg;
       if (LowerMallocArgToInteger)
         MallocArg = ConstantInt::get(Type::Int64Ty,
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index bcc6b81..ee0f6a6 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -859,6 +859,26 @@ static bool FoldValueComparisonIntoPredecessors(TerminatorInst *TI) {
   return Changed;
 }
 
+// isSafeToHoistInvoke - If we would need to insert a select that uses the
+// value of this invoke (comments in HoistThenElseCodeToIf explain why we
+// would need to do this), we can't hoist the invoke, as there is nowhere
+// to put the select in this case.
+static bool isSafeToHoistInvoke(BasicBlock *BB1, BasicBlock *BB2,
+                                Instruction *I1, Instruction *I2) {
+  for (succ_iterator SI = succ_begin(BB1), E = succ_end(BB1); SI != E; ++SI) {
+    PHINode *PN;
+    for (BasicBlock::iterator BBI = SI->begin();
+         (PN = dyn_cast<PHINode>(BBI)); ++BBI) {
+      Value *BB1V = PN->getIncomingValueForBlock(BB1);
+      Value *BB2V = PN->getIncomingValueForBlock(BB2);
+      if (BB1V != BB2V && (BB1V==I1 || BB2V==I2)) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
 /// HoistThenElseCodeToIf - Given a conditional branch that goes to BB1 and
 /// BB2, hoist any common code in the two blocks up into the branch block.  The
 /// caller of this function guarantees that BI's block dominates BB1 and BB2.
@@ -879,8 +899,9 @@ static bool HoistThenElseCodeToIf(BranchInst *BI) {
     I1 = BB1_Itr++;
   while (isa<DbgInfoIntrinsic>(I2))
     I2 = BB2_Itr++;
-  if (I1->getOpcode() != I2->getOpcode() || isa<PHINode>(I1) || 
-      isa<InvokeInst>(I1) || !I1->isIdenticalTo(I2))
+  if (I1->getOpcode() != I2->getOpcode() || isa<PHINode>(I1) ||
+      !I1->isIdenticalTo(I2) ||
+      (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2)))
     return false;
 
   // If we get here, we can hoist at least one instruction.
@@ -911,6 +932,10 @@ static bool HoistThenElseCodeToIf(BranchInst *BI) {
   return true;
 
 HoistTerminator:
+  // It may not be possible to hoist an invoke.
+  if (isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2))
+    return true;
+
   // Okay, it is safe to hoist the terminator.
   Instruction *NT = I1->clone();
   BIParent->getInstList().insert(BI, NT);