1 files changed, 25 insertions, 1 deletions
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index c783182..96fe94f 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -268,6 +268,10 @@ static cl::opt<unsigned>
     MaxAddressUsersToScan("cgp-max-address-users-to-scan", cl::init(100),
                           cl::Hidden,
                           cl::desc("Max number of address users to look at"));
+
+static cl::opt<unsigned> MaxLoopInvUsersToScan(
+    "cgp-max-loop-inv-users-to-scan", cl::init(20), cl::Hidden,
+    cl::desc("Max number of loop invariant users to look at"));
 namespace {
 
 enum ExtType {
@@ -5060,6 +5064,19 @@ static bool FindAllMemoryUses(
                            PSI, BFI, SeenInsts);
 }
 
+static bool isUsedInLoop(const Value *V, const Loop *L) {
+  unsigned N = 0;
+
+  for (const Use &U : V->uses()) {
+    if (++N > MaxLoopInvUsersToScan)
+      break;
+    const Instruction *UserI = cast<Instruction>(U.getUser());
+    if (L->contains(UserI->getParent()))
+      return true;
+  }
+
+  return false;
+}
 
 /// Return true if Val is already known to be live at the use site that we're
 /// folding it into. If so, there is no cost to include it in the addressing
@@ -5083,10 +5100,17 @@ bool AddressingModeMatcher::valueAlreadyLiveAtInst(Value *Val,
     if (AI->isStaticAlloca())
       return true;
 
+  // If the value is loop invariant and is used in the loop which contains the
+  // memory instruction, it's live.
+  BasicBlock *BB = MemoryInst->getParent();
+  if (Loop *L = LI.getLoopFor(BB);
+      L && L->isLoopInvariant(Val) && isUsedInLoop(Val, L))
+    return true;
+
   // Check to see if this value is already used in the memory instruction's
   // block.  If so, it's already live into the block at the very least, so we
   // can reasonably fold it.
-  return Val->isUsedInBasicBlock(MemoryInst->getParent());
+  return Val->isUsedInBasicBlock(BB);
 }
 
 /// It is possible for the addressing mode of the machine to fold the specified