From cca9aa58ca1594c3c74ee6c2055fbe23a6febdc7 Mon Sep 17 00:00:00 2001
From: Bob Wilson <bob.wilson@apple.com>
Date: Wed, 16 Nov 2011 07:57:21 +0000
Subject: [PATCH] Record landing pads with a SmallSetVector to avoid multiple
 entries.

There may be many invokes that share one landing pad, and the previous code
would record the landing pad once for each invoke.  Besides the wasted
effort, a pair of volatile loads gets inserted every time the landing pad is
processed.  The rest of the code can get optimized away when a landing pad
is processed repeatedly, but the volatile loads remain, resulting in code like:

LBB35_18:
Ltmp483:
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r2, [r7, #-72]
        ldr     r2, [r7, #-68]
        ldr     r4, [r7, #-72]
        ldr     r2, [r7, #-68]

llvm-svn: 144787
---
 llvm/lib/CodeGen/SjLjEHPrepare.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/CodeGen/SjLjEHPrepare.cpp b/llvm/lib/CodeGen/SjLjEHPrepare.cpp
index 5d60bc9b751a..c8651926c2fd 100644
--- a/llvm/lib/CodeGen/SjLjEHPrepare.cpp
+++ b/llvm/lib/CodeGen/SjLjEHPrepare.cpp
@@ -30,6 +30,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/IRBuilder.h"
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
@@ -364,13 +365,13 @@ void SjLjEHPass::lowerAcrossUnwindEdges(Function &F,
 bool SjLjEHPass::setupEntryBlockAndCallSites(Function &F) {
   SmallVector<ReturnInst*,     16> Returns;
   SmallVector<InvokeInst*,     16> Invokes;
-  SmallVector<LandingPadInst*, 16> LPads;
+  SmallSetVector<LandingPadInst*, 16> LPads;
 
   // Look through the terminators of the basic blocks to find invokes.
   for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
     if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
       Invokes.push_back(II);
-      LPads.push_back(II->getUnwindDest()->getLandingPadInst());
+      LPads.insert(II->getUnwindDest()->getLandingPadInst());
     } else if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
       Returns.push_back(RI);
     }
@@ -382,7 +383,8 @@ bool SjLjEHPass::setupEntryBlockAndCallSites(Function &F) {
   lowerIncomingArguments(F);
   lowerAcrossUnwindEdges(F, Invokes);
 
-  Value *FuncCtx = setupFunctionContext(F, LPads);
+  Value *FuncCtx =
+    setupFunctionContext(F, makeArrayRef(LPads.begin(), LPads.end()));
   BasicBlock *EntryBB = F.begin();
   Type *Int32Ty = Type::getInt32Ty(F.getContext());