1 files changed, 10 insertions, 25 deletions

diff --git a/lib/CodeGen/SjLjEHPrepare.cpp b/lib/CodeGen/SjLjEHPrepare.cpp
index 17a3a84ecda5..5d2669f5ae92 100644
--- a/lib/CodeGen/SjLjEHPrepare.cpp
+++ b/lib/CodeGen/SjLjEHPrepare.cpp
@@ -16,6 +16,7 @@
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/Transforms/Utils/Local.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
@@ -27,7 +28,6 @@
 #include "llvm/Pass.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/Transforms/Utils/Local.h"
 using namespace llvm;
 
 #define DEBUG_TYPE "sjljehprepare"
@@ -64,7 +64,6 @@ public:
 
 private:
   bool setupEntryBlockAndCallSites(Function &F);
-  bool undoSwiftErrorSelect(Function &F);
   void substituteLPadValues(LandingPadInst *LPI, Value *ExnVal, Value *SelVal);
   Value *setupFunctionContext(Function &F, ArrayRef<LandingPadInst *> LPads);
   void lowerIncomingArguments(Function &F);
@@ -233,6 +232,13 @@ void SjLjEHPrepare::lowerIncomingArguments(Function &F) {
   assert(AfterAllocaInsPt != F.front().end());
 
   for (auto &AI : F.args()) {
+    // Swift error really is a register that we model as memory -- instruction
+    // selection will perform mem-to-reg for us and spill/reload appropriately
+    // around calls that clobber it. There is no need to spill this
+    // value to the stack and doing so would not be allowed.
+    if (AI.isSwiftError())
+      continue;
+
     Type *Ty = AI.getType();
 
     // Use 'select i8 true, %arg, undef' to simulate a 'no-op' instruction.
@@ -301,8 +307,8 @@ void SjLjEHPrepare::lowerAcrossUnwindEdges(Function &F,
       for (InvokeInst *Invoke : Invokes) {
         BasicBlock *UnwindBlock = Invoke->getUnwindDest();
         if (UnwindBlock != &BB && LiveBBs.count(UnwindBlock)) {
-          DEBUG(dbgs() << "SJLJ Spill: " << Inst << " around "
-                       << UnwindBlock->getName() << "\n");
+          LLVM_DEBUG(dbgs() << "SJLJ Spill: " << Inst << " around "
+                            << UnwindBlock->getName() << "\n");
           NeedsSpill = true;
           break;
         }
@@ -462,25 +468,6 @@ bool SjLjEHPrepare::setupEntryBlockAndCallSites(Function &F) {
   return true;
 }
 
-bool SjLjEHPrepare::undoSwiftErrorSelect(Function &F) {
-  // We have inserted dummy copies 'select true, arg, undef' in the entry block
-  // for arguments to simplify this pass.
-  // swifterror arguments cannot be used in this way. Undo the select for the
-  // swifterror argument.
-  for (auto &AI : F.args()) {
-    if (AI.isSwiftError()) {
-      assert(AI.hasOneUse() && "Must have converted the argument to a select");
-      auto *Select = dyn_cast<SelectInst>(AI.use_begin()->getUser());
-      assert(Select && "There must be single select user");
-      auto *OrigSwiftError = cast<Argument>(Select->getTrueValue());
-      Select->replaceAllUsesWith(OrigSwiftError);
-      Select->eraseFromParent();
-      return true;
-    }
-  }
-  return false;
-}
-
 bool SjLjEHPrepare::runOnFunction(Function &F) {
   Module &M = *F.getParent();
   RegisterFn = M.getOrInsertFunction(
@@ -499,7 +486,5 @@ bool SjLjEHPrepare::runOnFunction(Function &F) {
   FuncCtxFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_functioncontext);
 
   bool Res = setupEntryBlockAndCallSites(F);
-  if (Res)
-    Res |= undoSwiftErrorSelect(F);
   return Res;
 }