[SEH] Reimplement x64 SEH using WinEHPrepare

This now emits simple, unoptimized xdata tables for __C_specific_handler
based on the handlers listed in @llvm.eh.actions calls produced by
WinEHPrepare.

This adds support for running __finally blocks when exceptions are
thrown, and removes the old landingpad fan-in codepath.

I ran some manual execution tests on small basic test cases with and
without optimization, as well as on Chrome base_unittests, which uses a
small amount of SEH.  I'm sure there are bugs, and we may need to
revert.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235154 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/MachineModuleInfo.h

@@ -51,6 +51,7 @@ namespace llvm {
 // Forward declarations.
 class Constant;
 class GlobalVariable;
+class BlockAddress;
 class MDNode;
 class MMIAddrLabelMap;
 class MachineBasicBlock;
@@ -60,6 +61,14 @@ class PointerType;
 class StructType;
 struct WinEHFuncInfo;
 
+struct SEHHandler {
+  // Filter or finally function. Null indicates a catch-all.
+  const Function *FilterOrFinally;
+
+  // Address of block to recover at. Null for a finally handler.
+  const BlockAddress *RecoverBA;
+};
+
 //===----------------------------------------------------------------------===//
 /// LandingPadInfo - This structure is used to retain landing pad info for
 /// the current function.
@@ -68,7 +77,7 @@ struct LandingPadInfo {
   MachineBasicBlock *LandingPadBlock;      // Landing pad block.
   SmallVector<MCSymbol *, 1> BeginLabels;  // Labels prior to invoke.
   SmallVector<MCSymbol *, 1> EndLabels;    // Labels after invoke.
-  SmallVector<MCSymbol *, 1> ClauseLabels; // Labels for each clause.
+  SmallVector<SEHHandler, 1> SEHHandlers;  // SEH handlers active at this lpad.
   MCSymbol *LandingPadLabel;               // Label at beginning of landing pad.
   const Function *Personality;             // Personality function.
   std::vector<int> TypeIds;               // List of type ids (filters negative).
@@ -351,10 +360,11 @@ public:
   ///
   void addCleanup(MachineBasicBlock *LandingPad);
 
-  /// Add a clause for a landing pad. Returns a new label for the clause. This
-  /// is used by EH schemes that have more than one landing pad. In this case,
-  /// each clause gets its own basic block.
-  MCSymbol *addClauseForLandingPad(MachineBasicBlock *LandingPad);
+  void addSEHCatchHandler(MachineBasicBlock *LandingPad, const Function *Filter,
+                          const BlockAddress *RecoverLabel);
+
+  void addSEHCleanupHandler(MachineBasicBlock *LandingPad,
+                            const Function *Cleanup);
 
   /// getTypeIDFor - Return the type id for the specified typeinfo.  This is
   /// function wide.