[WinEH] Update SplitAnalysis::computeLastSplitPoint to cope with multiple EH successors

We didn't have logic to correctly handle CFGs where there was more than
one EH-pad successor (these are novel with WinEH).
There were situations where a register was live in one exceptional
successor but not another but the code as written would only consider
the first exceptional successor it found.

This resulted in split points which were insufficiently early if an
invoke was present.

This fixes PR27501.

N.B.  This removes getLandingPadSuccessor.

llvm-svn: 267412

5 files changed, 87 insertions, 18 deletions

diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
index 0d547c29572..11be19607f8 100644
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -383,6 +383,14 @@ bool any_of(R &&Range, UnaryPredicate &&P) {
                      std::forward<UnaryPredicate>(P));
 }
 
+/// Provide wrappers to std::none_of which take ranges instead of having to pass
+/// begin/end explicitly.
+template <typename R, class UnaryPredicate>
+bool none_of(R &&Range, UnaryPredicate &&P) {
+  return std::none_of(Range.begin(), Range.end(),
+                      std::forward<UnaryPredicate>(P));
+}
+
 /// Provide wrappers to std::find which take ranges instead of having to pass
 /// begin/end explicitly.
 template<typename R, class T>
diff --git a/llvm/include/llvm/CodeGen/MachineBasicBlock.h b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
index da30243bcd4..d0ff0c978ba 100644
--- a/llvm/include/llvm/CodeGen/MachineBasicBlock.h
+++ b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
@@ -342,10 +342,6 @@ public:
   /// via an exception handler.
   void setIsEHPad(bool V = true) { IsEHPad = V; }
 
-  /// If this block has a successor that is a landing pad, return it. Otherwise
-  /// return NULL.
-  const MachineBasicBlock *getLandingPadSuccessor() const;
-
   bool hasEHPadSuccessor() const;
 
   /// Returns true if this is the entry block of an EH funclet.
diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index 318a2aa69d4..8b3f01fe58c 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -198,16 +198,6 @@ MachineBasicBlock::iterator MachineBasicBlock::getLastNonDebugInstr() {
   return end();
 }
 
-const MachineBasicBlock *MachineBasicBlock::getLandingPadSuccessor() const {
-  // A block with a landing pad successor only has one other successor.
-  if (succ_size() > 2)
-    return nullptr;
-  for (const_succ_iterator I = succ_begin(), E = succ_end(); I != E; ++I)
-    if ((*I)->isEHPad())
-      return *I;
-  return nullptr;
-}
-
 bool MachineBasicBlock::hasEHPadSuccessor() const {
   for (const_succ_iterator I = succ_begin(), E = succ_end(); I != E; ++I)
     if ((*I)->isEHPad())
diff --git a/llvm/lib/CodeGen/SplitKit.cpp b/llvm/lib/CodeGen/SplitKit.cpp
index 436d5bb21d9..8bf139156ee 100644
--- a/llvm/lib/CodeGen/SplitKit.cpp
+++ b/llvm/lib/CodeGen/SplitKit.cpp
@@ -57,11 +57,14 @@ 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);
 
+  SmallVector<const MachineBasicBlock *, 1> EHPadSucessors;
+  for (const MachineBasicBlock *SMBB : MBB->successors())
+    if (SMBB->isEHPad())
+      EHPadSucessors.push_back(SMBB);
+
   // Compute split points on the first call. The pair is independent of the
   // current live interval.
   if (!LSP.first.isValid()) {
@@ -72,7 +75,7 @@ SlotIndex SplitAnalysis::computeLastSplitPoint(unsigned Num) {
       LSP.first = LIS.getInstructionIndex(*FirstTerm);
 
     // If there is a landing pad successor, also find the call instruction.
-    if (!LPad)
+    if (EHPadSucessors.empty())
       return LSP.first;
     // There may not be a call instruction (?) in which case we ignore LPad.
     LSP.second = LSP.first;
@@ -88,7 +91,12 @@ SlotIndex SplitAnalysis::computeLastSplitPoint(unsigned Num) {
 
   // If CurLI is live into a landing pad successor, move the last split point
   // back to the call that may throw.
-  if (!LPad || !LSP.second || !LIS.isLiveInToMBB(*CurLI, LPad))
+  if (!LSP.second)
+    return LSP.first;
+
+  if (none_of(EHPadSucessors, [&](const MachineBasicBlock *EHPad) {
+        return LIS.isLiveInToMBB(*CurLI, EHPad);
+      }))
     return LSP.first;
 
   // Find the value leaving MBB.
diff --git a/llvm/test/CodeGen/X86/pr27501.ll b/llvm/test/CodeGen/X86/pr27501.ll
new file mode 100644
index 00000000000..bde41214471
--- /dev/null
+++ b/llvm/test/CodeGen/X86/pr27501.ll
@@ -0,0 +1,67 @@
+; RUN: llc < %s | FileCheck %s
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc"
+
+define void @test1(i64* %result.repack) personality i32 (...)* @__CxxFrameHandler3 {
+bb:
+  invoke void @may_throw(i32 1)
+          to label %postinvoke unwind label %cleanuppad
+; CHECK:        movl    $1, %ecx
+; CHECK:        callq   may_throw
+
+postinvoke:                                       ; preds = %bb
+  store i64 19, i64* %result.repack, align 8
+
+; CHECK:        movq    $19, (%rsi)
+; CHECK:        movl    $2, %ecx
+; CHECK-NEXT:   movq    %rsi, -8(%rbp)
+; CHECK-NEXT:   callq   may_throw
+  invoke void @may_throw(i32 2)
+          to label %assertFailed unwind label %catch.dispatch
+
+catch.dispatch:                                   ; preds = %cleanuppad9, %postinvoke
+  %tmp3 = catchswitch within none [label %catch.object.Throwable] unwind label %cleanuppad
+
+catch.object.Throwable:                           ; preds = %catch.dispatch
+  %tmp2 = catchpad within %tmp3 [i8* null, i32 64, i8* null]
+  catchret from %tmp2 to label %catchhandler
+
+catchhandler:                                     ; preds = %catch.object.Throwable
+  invoke void @may_throw(i32 3)
+          to label %try.success.or.caught unwind label %cleanuppad
+
+try.success.or.caught:                            ; preds = %catchhandler
+  invoke void @may_throw(i32 4)
+          to label %postinvoke27 unwind label %cleanuppad24
+; CHECK:        movl    $4, %ecx
+; CHECK-NEXT:   callq   may_throw
+
+postinvoke27:                                     ; preds = %try.success.or.caught
+  store i64 42, i64* %result.repack, align 8
+; CHECK:        movq    -8(%rbp), %[[reload:r..]]
+; CHECK-NEXT:   movq    $42, (%[[reload]])
+  ret void
+
+cleanuppad24:                                     ; preds = %try.success.or.caught
+  %tmp5 = cleanuppad within none []
+  cleanupret from %tmp5 unwind to caller
+
+cleanuppad:                                       ; preds = %catchhandler, %catch.dispatch, %bb
+  %tmp1 = cleanuppad within none []
+  cleanupret from %tmp1 unwind to caller
+
+assertFailed:                                     ; preds = %postinvoke
+  invoke void @may_throw(i32 5)
+          to label %postinvoke13 unwind label %cleanuppad9
+
+postinvoke13:                                     ; preds = %assertFailed
+  unreachable
+
+cleanuppad9:                                      ; preds = %assertFailed
+  %tmp4 = cleanuppad within none []
+  cleanupret from %tmp4 unwind label %catch.dispatch
+}
+
+declare void @may_throw(i32)
+
+declare i32 @__CxxFrameHandler3(...)