From 43488710a8dc76b39f9f3b628c2fdd5d34aa0dbb Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Mon, 14 Sep 2009 20:52:37 +0000
Subject: [PATCH] Pull the creation of the "RewindFunction" function out of the
 loop. It's only created once, so shouldn't be stuck in the middle of the
 loop. Also early exit if there are no uses of UnwindInst in the function.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81785 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/DwarfEHPrepare.cpp | 39 ++++++++++++++++++++++------------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/lib/CodeGen/DwarfEHPrepare.cpp b/lib/CodeGen/DwarfEHPrepare.cpp
index a2e6068ff87..be6205e174a 100644
--- a/lib/CodeGen/DwarfEHPrepare.cpp
+++ b/lib/CodeGen/DwarfEHPrepare.cpp
@@ -219,29 +219,40 @@ bool DwarfEHPrepare::NormalizeLandingPads() {
 /// at runtime if there is no such exception: using unwind to throw a new
 /// exception is currently not supported.
 bool DwarfEHPrepare::LowerUnwinds() {
-  bool Changed = false;
+  SmallVector<TerminatorInst*, 16> UnwindInsts;
 
   for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
     TerminatorInst *TI = I->getTerminator();
-    if (!isa<UnwindInst>(TI))
-      continue;
+    if (isa<UnwindInst>(TI))
+      UnwindInsts.push_back(TI);
+  }
+
+  if (UnwindInsts.empty()) return false;
+
+  // Find the rewind function if we didn't already.
+  if (!RewindFunction) {
+    LLVMContext &Ctx = UnwindInsts[0]->getContext();
+    std::vector<const Type*>
+      Params(1, PointerType::getUnqual(Type::getInt8Ty(Ctx)));
+    FunctionType *FTy = FunctionType::get(Type::getVoidTy(Ctx),
+                                          Params, false);
+    const char *RewindName = TLI->getLibcallName(RTLIB::UNWIND_RESUME);
+    RewindFunction = F->getParent()->getOrInsertFunction(RewindName, FTy);
+  }
+
+  bool Changed = false;
+
+  for (SmallVectorImpl<TerminatorInst*>::iterator
+         I = UnwindInsts.begin(), E = UnwindInsts.end(); I != E; ++I) {
+    TerminatorInst *TI = *I;
 
     // Replace the unwind instruction with a call to _Unwind_Resume (or the
     // appropriate target equivalent) followed by an UnreachableInst.
 
-    // Find the rewind function if we didn't already.
-    if (!RewindFunction) {
-      std::vector<const Type*> Params(1,
-                     PointerType::getUnqual(Type::getInt8Ty(TI->getContext())));
-      FunctionType *FTy = FunctionType::get(Type::getVoidTy(TI->getContext()),
-                                            Params, false);
-      const char *RewindName = TLI->getLibcallName(RTLIB::UNWIND_RESUME);
-      RewindFunction = F->getParent()->getOrInsertFunction(RewindName, FTy);
-    }
-
     // Create the call...
     CallInst *CI = CallInst::Create(RewindFunction,
-				    CreateReadOfExceptionValue(I), "", TI);
+				    CreateReadOfExceptionValue(TI->getParent()),
+                                    "", TI);
     CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
     // ...followed by an UnreachableInst.
     new UnreachableInst(TI->getContext(), TI);