[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

6 files changed, 128 insertions, 2 deletions

diff --git a/llvm/include/llvm/CodeGen/MachineBasicBlock.h b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
index 4124a836571..c29055d0889 100644
--- a/llvm/include/llvm/CodeGen/MachineBasicBlock.h
+++ b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
@@ -381,6 +381,8 @@ public:
   /// return NULL.
   const MachineBasicBlock *getLandingPadSuccessor() const;
 
+  bool hasEHPadSuccessor() const;
+
   /// Returns true if this is the entry block of an EH funclet.
   bool isEHFuncletEntry() const { return IsEHFuncletEntry; }
 
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))
diff --git a/llvm/test/CodeGen/X86/tail-merge-wineh.ll b/llvm/test/CodeGen/X86/tail-merge-wineh.ll
new file mode 100644
index 00000000000..03cc9a8fe6b
--- /dev/null
+++ b/llvm/test/CodeGen/X86/tail-merge-wineh.ll
@@ -0,0 +1,116 @@
+; RUN: llc < %s | FileCheck %s
+
+; Started from this code:
+; void f() {
+;   try {
+;     try {
+;       throw 42;
+;     } catch (int) {
+;     }
+;     try {
+;       throw 42;
+;     } catch (int) {
+;     }
+;   } catch (int) {
+;   }
+; }
+
+; Don't tail merge the calls.
+; CHECK: calll _CxxThrowException
+; CHECK: calll _CxxThrowException
+
+; ModuleID = 'cppeh-pingpong.cpp'
+target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
+target triple = "i686-pc-windows-msvc"
+
+%rtti.TypeDescriptor2 = type { i8**, i8*, [3 x i8] }
+%eh.CatchableType = type { i32, i8*, i32, i32, i32, i32, i8* }
+%eh.CatchableTypeArray.1 = type { i32, [1 x %eh.CatchableType*] }
+%eh.ThrowInfo = type { i32, i8*, i8*, i8* }
+
+$"\01??_R0H@8" = comdat any
+
+$"_CT??_R0H@84" = comdat any
+
+$_CTA1H = comdat any
+
+$_TI1H = comdat any
+
+@"\01??_7type_info@@6B@" = external constant i8*
+@"\01??_R0H@8" = linkonce_odr global %rtti.TypeDescriptor2 { i8** @"\01??_7type_info@@6B@", i8* null, [3 x i8] c".H\00" }, comdat
+@"_CT??_R0H@84" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 1, i8* bitcast (%rtti.TypeDescriptor2* @"\01??_R0H@8" to i8*), i32 0, i32 -1, i32 0, i32 4, i8* null }, section ".xdata", comdat
+@_CTA1H = linkonce_odr unnamed_addr constant %eh.CatchableTypeArray.1 { i32 1, [1 x %eh.CatchableType*] [%eh.CatchableType* @"_CT??_R0H@84"] }, section ".xdata", comdat
+@_TI1H = linkonce_odr unnamed_addr constant %eh.ThrowInfo { i32 0, i8* null, i8* null, i8* bitcast (%eh.CatchableTypeArray.1* @_CTA1H to i8*) }, section ".xdata", comdat
+
+define void @"\01?f@@YAXXZ"() #0 personality i8* bitcast (i32 (...)* @__CxxFrameHandler3 to i8*) {
+entry:
+  %i = alloca i32, align 4
+  %tmp = alloca i32, align 4
+  %tmp1 = alloca i32, align 4
+  store i32 0, i32* %i, align 4
+  store i32 42, i32* %tmp, align 4
+  %0 = bitcast i32* %tmp to i8*
+  invoke void @_CxxThrowException(i8* %0, %eh.ThrowInfo* @_TI1H) #1
+          to label %unreachable unwind label %catch.dispatch
+
+catch.dispatch:                                   ; preds = %entry
+  %1 = catchpad [%rtti.TypeDescriptor2* @"\01??_R0H@8", i32 0, i8* null]
+          to label %catch unwind label %catchendblock
+
+catch:                                            ; preds = %catch.dispatch
+  catchret %1 to label %catchret.dest
+
+catchret.dest:                                    ; preds = %catch
+  br label %try.cont
+
+try.cont:                                         ; preds = %catchret.dest
+  store i32 42, i32* %tmp1, align 4
+  %2 = bitcast i32* %tmp1 to i8*
+  invoke void @_CxxThrowException(i8* %2, %eh.ThrowInfo* @_TI1H) #1
+          to label %unreachable unwind label %catch.dispatch.2
+
+catch.dispatch.2:                                 ; preds = %try.cont
+  %3 = catchpad [%rtti.TypeDescriptor2* @"\01??_R0H@8", i32 0, i8* null]
+          to label %catch.4 unwind label %catchendblock.3
+
+catch.4:                                          ; preds = %catch.dispatch.2
+  catchret %3 to label %catchret.dest.5
+
+catchret.dest.5:                                  ; preds = %catch.4
+  br label %try.cont.6
+
+try.cont.6:                                       ; preds = %catchret.dest.5
+  br label %try.cont.11
+
+catchendblock.3:                                  ; preds = %catch.dispatch.2
+  catchendpad unwind label %catch.dispatch.7
+
+catch.dispatch.7:                                 ; preds = %catchendblock.3, %catchendblock
+  %4 = catchpad [%rtti.TypeDescriptor2* @"\01??_R0H@8", i32 0, i8* null]
+          to label %catch.9 unwind label %catchendblock.8
+
+catch.9:                                          ; preds = %catch.dispatch.7
+  catchret %4 to label %catchret.dest.10
+
+catchret.dest.10:                                 ; preds = %catch.9
+  br label %try.cont.11
+
+try.cont.11:                                      ; preds = %catchret.dest.10, %try.cont.6
+  ret void
+
+catchendblock.8:                                  ; preds = %catch.dispatch.7
+  catchendpad unwind to caller
+
+catchendblock:                                    ; preds = %catch.dispatch
+  catchendpad unwind label %catch.dispatch.7
+
+unreachable:                                      ; preds = %try.cont, %entry
+  unreachable
+}
+
+declare x86_stdcallcc void @_CxxThrowException(i8*, %eh.ThrowInfo*)
+
+declare i32 @__CxxFrameHandler3(...)
+
+attributes #0 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { noreturn }