[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.

llvm-svn: 235154

1 files changed, 53 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index 4b8ae32e9a5..bb40326ba2d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -270,12 +270,21 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
   }
 
   // Mark landing pad blocks.
-  for (BB = Fn->begin(); BB != EB; ++BB)
+  const LandingPadInst *LP = nullptr;
+  for (BB = Fn->begin(); BB != EB; ++BB) {
     if (const auto *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
       MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
+    if (BB->isLandingPad())
+      LP = BB->getLandingPadInst();
+  }
 
-  // Calculate EH numbers for WinEH.
-  if (fn.hasFnAttribute("wineh-parent")) {
+  // Calculate EH numbers for MSVC C++ EH and save SEH handlers if necessary.
+  EHPersonality Personality = EHPersonality::Unknown;
+  if (LP)
+    Personality = classifyEHPersonality(LP->getPersonalityFn());
+  if (Personality == EHPersonality::MSVC_Win64SEH) {
+    addSEHHandlersForLPads();
+  } else if (Personality == EHPersonality::MSVC_CXX) {
     const Function *WinEHParentFn = MMI.getWinEHParent(&fn);
     WinEHFuncInfo &FI = MMI.getWinEHFuncInfo(WinEHParentFn);
     if (FI.LandingPadStateMap.empty()) {
@@ -287,6 +296,47 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
   }
 }
 
+void FunctionLoweringInfo::addSEHHandlersForLPads() {
+  MachineModuleInfo &MMI = MF->getMMI();
+
+  // Iterate over all landing pads with llvm.eh.actions calls.
+  for (const BasicBlock &BB : *Fn) {
+    const LandingPadInst *LP = BB.getLandingPadInst();
+    if (!LP)
+      continue;
+    const IntrinsicInst *ActionsCall =
+        dyn_cast<IntrinsicInst>(LP->getNextNode());
+    if (!ActionsCall ||
+        ActionsCall->getIntrinsicID() != Intrinsic::eh_actions)
+      continue;
+
+    // Parse the llvm.eh.actions call we found.
+    MachineBasicBlock *LPadMBB = MBBMap[LP->getParent()];
+    SmallVector<ActionHandler *, 4> Actions;
+    parseEHActions(ActionsCall, Actions);
+
+    // Iterate EH actions from most to least precedence, which means
+    // iterating in reverse.
+    for (auto I = Actions.rbegin(), E = Actions.rend(); I != E; ++I) {
+      ActionHandler *Action = *I;
+      if (auto *CH = dyn_cast<CatchHandler>(Action)) {
+        const auto *Filter =
+            dyn_cast<Function>(CH->getSelector()->stripPointerCasts());
+        assert((Filter || CH->getSelector()->isNullValue()) &&
+               "expected function or catch-all");
+        const auto *RecoverBA =
+            cast<BlockAddress>(CH->getHandlerBlockOrFunc());
+        MMI.addSEHCatchHandler(LPadMBB, Filter, RecoverBA);
+      } else {
+        assert(isa<CleanupHandler>(Action));
+        const auto *Fini = cast<Function>(Action->getHandlerBlockOrFunc());
+        MMI.addSEHCleanupHandler(LPadMBB, Fini);
+      }
+    }
+    DeleteContainerPointers(Actions);
+  }
+}
+
 void WinEHNumbering::createUnwindMapEntry(int ToState, ActionHandler *AH) {
   WinEHUnwindMapEntry UME;
   UME.ToState = ToState;