From 6212b4d0b8f337180a7c54b1da25da27897b247b Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Mon, 5 Oct 2015 20:09:16 +0000
Subject: [PATCH] [WinEH] Update CATCHRET's operand to match its successor

The CATCHRET operand did not match the MachineFunction's CFG.  This
mismatch happened because FrameLowering created a new MachineBasicBlock
and updated the CFG but forgot to update the CATCHRET operand.

Let's make sure this doesn't happen again by strengthing the funclet
membership analysis: it can now reason about the membership of all basic
blocks, not just those inside of funclets.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249344 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/Analysis.cpp            | 28 +++++++++++++++++++++-------
 lib/CodeGen/FuncletLayout.cpp       |  8 ++++++--
 lib/Target/X86/X86FrameLowering.cpp |  1 +
 3 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/lib/CodeGen/Analysis.cpp b/lib/CodeGen/Analysis.cpp
index 41fad1eb7ba..0f7e83a8470 100644
--- a/lib/CodeGen/Analysis.cpp
+++ b/lib/CodeGen/Analysis.cpp
@@ -688,25 +688,36 @@ llvm::getFuncletMembership(const MachineFunction &MF) {
   if (!MF.getMMI().hasEHFunclets())
     return FuncletMembership;
 
+  int EntryBBNumber = MF.front().getNumber();
   bool IsSEH = isAsynchronousEHPersonality(
       classifyEHPersonality(MF.getFunction()->getPersonalityFn()));
 
   const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
   SmallVector<const MachineBasicBlock *, 16> FuncletBlocks;
+  SmallVector<const MachineBasicBlock *, 16> UnreachableBlocks;
+  SmallVector<const MachineBasicBlock *, 16> SEHCatchPads;
   SmallVector<std::pair<const MachineBasicBlock *, int>, 16> CatchRetSuccessors;
   for (const MachineBasicBlock &MBB : MF) {
-    if (MBB.isEHFuncletEntry())
+    if (MBB.isEHFuncletEntry()) {
       FuncletBlocks.push_back(&MBB);
+    } else if (IsSEH && MBB.isEHPad()) {
+      SEHCatchPads.push_back(&MBB);
+    } else if (MBB.pred_empty()) {
+      UnreachableBlocks.push_back(&MBB);
+    }
 
     MachineBasicBlock::const_iterator MBBI = MBB.getFirstTerminator();
     // CatchPads are not funclets for SEH so do not consider CatchRet to
     // transfer control to another funclet.
-    if (IsSEH || MBBI->getOpcode() != TII->getCatchReturnOpcode())
+    if (MBBI->getOpcode() != TII->getCatchReturnOpcode())
       continue;
 
+    // FIXME: SEH CatchPads are not necessarily in the parent function:
+    // they could be inside a finally block.
     const MachineBasicBlock *Successor = MBBI->getOperand(0).getMBB();
     const MachineBasicBlock *SuccessorColor = MBBI->getOperand(1).getMBB();
-    CatchRetSuccessors.push_back({Successor, SuccessorColor->getNumber()});
+    CatchRetSuccessors.push_back(
+        {Successor, IsSEH ? EntryBBNumber : SuccessorColor->getNumber()});
   }
 
   // We don't have anything to do if there aren't any EH pads.
@@ -714,17 +725,20 @@ llvm::getFuncletMembership(const MachineFunction &MF) {
     return FuncletMembership;
 
   // Identify all the basic blocks reachable from the function entry.
-  collectFuncletMembers(FuncletMembership, MF.front().getNumber(), MF.begin());
+  collectFuncletMembers(FuncletMembership, EntryBBNumber, MF.begin());
+  // All blocks not part of a funclet are in the parent function.
+  for (const MachineBasicBlock *MBB : UnreachableBlocks)
+    collectFuncletMembers(FuncletMembership, EntryBBNumber, MBB);
   // Next, identify all the blocks inside the funclets.
   for (const MachineBasicBlock *MBB : FuncletBlocks)
     collectFuncletMembers(FuncletMembership, MBB->getNumber(), MBB);
+  // SEH CatchPads aren't really funclets, handle them separately.
+  for (const MachineBasicBlock *MBB : SEHCatchPads)
+    collectFuncletMembers(FuncletMembership, EntryBBNumber, MBB);
   // Finally, identify all the targets of a catchret.
   for (std::pair<const MachineBasicBlock *, int> CatchRetPair :
        CatchRetSuccessors)
     collectFuncletMembers(FuncletMembership, CatchRetPair.second,
                           CatchRetPair.first);
-  // All blocks not part of a funclet are in the parent function.
-  for (const MachineBasicBlock &MBB : MF)
-    FuncletMembership.insert({&MBB, MF.front().getNumber()});
   return FuncletMembership;
 }
diff --git a/lib/CodeGen/FuncletLayout.cpp b/lib/CodeGen/FuncletLayout.cpp
index 4307c1524ad..8b2f505ff02 100644
--- a/lib/CodeGen/FuncletLayout.cpp
+++ b/lib/CodeGen/FuncletLayout.cpp
@@ -42,8 +42,12 @@ bool FuncletLayout::runOnMachineFunction(MachineFunction &F) {
   if (FuncletMembership.empty())
     return false;
 
-  F.sort([&](MachineBasicBlock &x, MachineBasicBlock &y) {
-    return FuncletMembership[&x] < FuncletMembership[&y];
+  F.sort([&](MachineBasicBlock &X, MachineBasicBlock &Y) {
+    auto FuncletX = FuncletMembership.find(&X);
+    auto FuncletY = FuncletMembership.find(&Y);
+    assert(FuncletX != FuncletMembership.end());
+    assert(FuncletY != FuncletMembership.end());
+    return FuncletX->second < FuncletY->second;
   });
 
   // Conservatively assume we changed something.
diff --git a/lib/Target/X86/X86FrameLowering.cpp b/lib/Target/X86/X86FrameLowering.cpp
index c2c9f07ee10..1895cd87b10 100644
--- a/lib/Target/X86/X86FrameLowering.cpp
+++ b/lib/Target/X86/X86FrameLowering.cpp
@@ -1088,6 +1088,7 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
       MBB.removeSuccessor(TargetMBB);
       MBB.addSuccessor(RestoreMBB);
       RestoreMBB->addSuccessor(TargetMBB);
+      MBBI->getOperand(0).setMBB(RestoreMBB);
     }
 
     // Fill EAX/RAX with the address of the target block.
-- 
2.34.1