[WinEH] Add and use hasEHPadSuccessor instead of getLandingPadSuccessor

getLandingPadSuccessor assumes that each invoke can have at most one EH
pad successor, but WinEH invokes can have more than one. Two out of
three callers of getLandingPadSuccessor don't use the returned
landingpad, so we can make them use this simple predicate instead.

Eventually we'll have to circle back and fix SplitKit.cpp so that
register allocation works. Baby steps.

llvm-svn: 247904

4 files changed, 10 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
index f990e100864..2ef8889091f 100644
--- a/llvm/lib/CodeGen/BranchFolding.cpp
+++ b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -976,7 +976,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
         continue;
 
       // Skip blocks which may jump to a landing pad. Can't tail merge these.
-      if (PBB->getLandingPadSuccessor())
+      if (PBB->hasEHPadSuccessor())
         continue;
 
       MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index a968ab95146..e4d6e66b6e7 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -208,6 +208,13 @@ const MachineBasicBlock *MachineBasicBlock::getLandingPadSuccessor() const {
   return nullptr;
 }
 
+bool MachineBasicBlock::hasEHPadSuccessor() const {
+  for (const_succ_iterator I = succ_begin(), E = succ_end(); I != E; ++I)
+    if ((*I)->isEHPad())
+      return true;
+  return false;
+}
+
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 void MachineBasicBlock::dump() const {
   print(dbgs());
diff --git a/llvm/lib/CodeGen/SplitKit.cpp b/llvm/lib/CodeGen/SplitKit.cpp
index dab1dfe4f1f..d06a316ba6c 100644
--- a/llvm/lib/CodeGen/SplitKit.cpp
+++ b/llvm/lib/CodeGen/SplitKit.cpp
@@ -56,6 +56,7 @@ void SplitAnalysis::clear() {
 
 SlotIndex SplitAnalysis::computeLastSplitPoint(unsigned Num) {
   const MachineBasicBlock *MBB = MF.getBlockNumbered(Num);
+  // FIXME: Handle multiple EH pad successors.
   const MachineBasicBlock *LPad = MBB->getLandingPadSuccessor();
   std::pair<SlotIndex, SlotIndex> &LSP = LastSplitPoint[Num];
   SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB);
diff --git a/llvm/lib/CodeGen/TailDuplication.cpp b/llvm/lib/CodeGen/TailDuplication.cpp
index 4a71c668623..0a35daa535c 100644
--- a/llvm/lib/CodeGen/TailDuplication.cpp
+++ b/llvm/lib/CodeGen/TailDuplication.cpp
@@ -673,7 +673,7 @@ TailDuplicatePass::duplicateSimpleBB(MachineBasicBlock *TailBB,
        PE = Preds.end(); PI != PE; ++PI) {
     MachineBasicBlock *PredBB = *PI;
 
-    if (PredBB->getLandingPadSuccessor())
+    if (PredBB->hasEHPadSuccessor())
       continue;
 
     if (bothUsedInPHI(*PredBB, Succs))