In the new EH model, setup the function context and the call site info.

The DWARF exception pass uses the call site information, which is set up here. A
pre-RA pass is too late for it to use this information. So create and setup the
function context here, and then insert the call site values here (and map the
call sites for the DWARF EH pass). This is simpler than the original pass, and
doesn't make the CFG lose its SSA-ness.

It's a win-win-win-win-lose-win-win situation.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140675 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SjLjEHPrepare.cpp

@@ -22,16 +22,22 @@
 #include "llvm/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/CodeGen/Passes.h"
+#include "llvm/Target/TargetData.h"
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/IRBuilder.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include <set>
 using namespace llvm;
 
+static cl::opt<bool> DisableOldSjLjEH("disable-old-sjlj-eh", cl::Hidden,
+    cl::desc("Disable the old SjLj EH preparation pass"));
+
 STATISTIC(NumInvokes, "Number of invokes replaced");
 STATISTIC(NumUnwinds, "Number of unwinds replaced");
 STATISTIC(NumSpilled, "Number of registers live across unwind edges");
@@ -67,6 +73,9 @@ namespace {
     }
 
   private:
+    bool setupEntryBlockAndCallSites(Function &F);
+    void setupFunctionContext(Function &F, ArrayRef<LandingPadInst*> LPads);
+
     void insertCallSiteStore(Instruction *I, int Number, Value *CallSite);
     void markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite,
                             SwitchInst *CatchSwitch);
@@ -698,7 +707,178 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
   return true;
 }
 
+/// setupFunctionContext - Allocate the function context on the stack and fill
+/// it with all of the data that we know at this point.
+void SjLjEHPass::setupFunctionContext(Function &F,
+                                      ArrayRef<LandingPadInst*> LPads) {
+  BasicBlock *EntryBB = F.begin();
+
+  // Create an alloca for the incoming jump buffer ptr and the new jump buffer
+  // that needs to be restored on all exits from the function. This is an alloca
+  // because the value needs to be added to the global context list.
+  unsigned Align =
+    TLI->getTargetData()->getPrefTypeAlignment(FunctionContextTy);
+  AllocaInst *FuncCtx =
+    new AllocaInst(FunctionContextTy, 0, Align, "fn_context", EntryBB->begin());
+
+  // Fill in the function context structure.
+  Value *Idxs[2];
+  Type *Int32Ty = Type::getInt32Ty(F.getContext());
+  Value *Zero = ConstantInt::get(Int32Ty, 0);
+  Value *One = ConstantInt::get(Int32Ty, 1);
+
+  // Keep around a reference to the call_site field.
+  Idxs[0] = Zero;
+  Idxs[1] = One;
+  CallSite = GetElementPtrInst::Create(FuncCtx, Idxs, "call_site",
+                                       EntryBB->getTerminator());
+
+  // Reference the __data field.
+  Idxs[1] = ConstantInt::get(Int32Ty, 2);
+  Value *FCData = GetElementPtrInst::Create(FuncCtx, Idxs, "__data",
+                                            EntryBB->getTerminator());
+
+  // The exception value comes back in context->__data[0].
+  Idxs[1] = Zero;
+  Value *ExceptionAddr = GetElementPtrInst::Create(FCData, Idxs,
+                                                   "exception_gep",
+                                                   EntryBB->getTerminator());
+
+  // The exception selector comes back in context->__data[1].
+  Idxs[1] = One;
+  Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs,
+                                                  "exn_selector_gep",
+                                                  EntryBB->getTerminator());
+
+  for (unsigned I = 0, E = LPads.size(); I != E; ++I) {
+    LandingPadInst *LPI = LPads[I];
+    IRBuilder<> Builder(LPI->getParent()->getFirstInsertionPt());
+
+    Value *ExnVal = Builder.CreateLoad(ExceptionAddr, true, "exn_val");
+    ExnVal = Builder.CreateIntToPtr(ExnVal, Type::getInt8PtrTy(F.getContext()));
+    Value *SelVal = Builder.CreateLoad(SelectorAddr, true, "exn_selector_val");
+
+    Type *LPadType = LPI->getType();
+    Value *LPadVal = UndefValue::get(LPadType);
+    LPadVal = Builder.CreateInsertValue(LPadVal, ExnVal, 0, "lpad.val");
+    LPadVal = Builder.CreateInsertValue(LPadVal, SelVal, 1, "lpad.val");
+
+    LPI->replaceAllUsesWith(LPadVal);
+  }
+
+  // Personality function
+  Idxs[1] = ConstantInt::get(Int32Ty, 3);
+  if (!PersonalityFn)
+    PersonalityFn = LPads[0]->getPersonalityFn();
+  Value *PersonalityFieldPtr =
+    GetElementPtrInst::Create(FuncCtx, Idxs, "pers_fn_gep",
+                              EntryBB->getTerminator());
+  new StoreInst(PersonalityFn, PersonalityFieldPtr, true,
+                EntryBB->getTerminator());
+
+  // LSDA address
+  Idxs[1] = ConstantInt::get(Int32Ty, 4);
+  Value *LSDAFieldPtr =
+    GetElementPtrInst::Create(FuncCtx, Idxs, "lsda_gep",
+                              EntryBB->getTerminator());
+  Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr",
+                                 EntryBB->getTerminator());
+  new StoreInst(LSDA, LSDAFieldPtr, true, EntryBB->getTerminator());
+
+  // Get a reference to the jump buffer.
+  Idxs[1] = ConstantInt::get(Int32Ty, 5);
+  Value *JBufPtr =
+    GetElementPtrInst::Create(FuncCtx, Idxs, "jbuf_gep",
+                              EntryBB->getTerminator());
+  Idxs[1] = Zero;
+  Value *FramePtr =
+    GetElementPtrInst::Create(JBufPtr, Idxs, "jbuf_fp_gep",
+                              EntryBB->getTerminator());
+
+  // Save the frame pointer.
+  Value *Val = CallInst::Create(FrameAddrFn,
+                                ConstantInt::get(Int32Ty, 0),
+                                "fp",
+                                EntryBB->getTerminator());
+  new StoreInst(Val, FramePtr, true, EntryBB->getTerminator());
+
+  // Save the stack pointer.
+  Idxs[1] = ConstantInt::get(Int32Ty, 2);
+  Value *StackPtr =
+    GetElementPtrInst::Create(JBufPtr, Idxs, "jbuf_sp_gep",
+                              EntryBB->getTerminator());
+
+  Val = CallInst::Create(StackAddrFn, "sp", EntryBB->getTerminator());
+  new StoreInst(Val, StackPtr, true, EntryBB->getTerminator());
+
+  // Call the setjmp instrinsic. It fills in the rest of the jmpbuf.
+  Value *SetjmpArg =
+    CastInst::Create(Instruction::BitCast, JBufPtr,
+                     Type::getInt8PtrTy(F.getContext()), "",
+                     EntryBB->getTerminator());
+  Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg,
+                                        "dispatch",
+                                        EntryBB->getTerminator());
+
+  // Add a call to dispatch_setup after the setjmp call. This is expanded to any
+  // target-specific setup that needs to be done.
+  CallInst::Create(DispatchSetupFn, DispatchVal, "", EntryBB->getTerminator());
+}
+
+/// setupEntryBlockAndCallSites - Setup the entry block by creating and filling
+/// the function context and marking the call sites with the appropriate
+/// values. These values are used by the DWARF EH emitter.
+bool SjLjEHPass::setupEntryBlockAndCallSites(Function &F) {
+  SmallVector<InvokeInst*,     16> Invokes;
+  SmallVector<LandingPadInst*, 16> LPads;
+
+  // Look through the terminators of the basic blocks to find invokes.
+  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+    if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
+      Invokes.push_back(II);
+      LPads.push_back(II->getUnwindDest()->getLandingPadInst());
+    }
+
+  if (Invokes.empty()) return false;
+
+  setupFunctionContext(F, LPads);
+
+  // At this point, we are all set up, update the invoke instructions to mark
+  // their call_site values, and fill in the dispatch switch accordingly.
+  for (unsigned I = 0, E = Invokes.size(); I != E; ++I) {
+    insertCallSiteStore(Invokes[I], I + 1, CallSite);
+
+    ConstantInt *CallSiteNum =
+      ConstantInt::get(Type::getInt32Ty(F.getContext()), I + 1);
+
+    // Record the call site value for the back end so it stays associated with
+    // the invoke.
+    CallInst::Create(CallSiteFn, CallSiteNum, "", Invokes[I]);
+  }
+
+  // Mark call instructions that aren't nounwind as no-action (call_site ==
+  // -1). Skip the entry block, as prior to then, no function context has been
+  // created for this function and any unexpected exceptions thrown will go
+  // directly to the caller's context, which is what we want anyway, so no need
+  // to do anything here.
+  for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) {
+    for (BasicBlock::iterator I = BB->begin(), end = BB->end(); I != end; ++I)
+      if (CallInst *CI = dyn_cast<CallInst>(I)) {
+        if (!CI->doesNotThrow())
+          insertCallSiteStore(CI, -1, CallSite);
+      } else if (ResumeInst *RI = dyn_cast<ResumeInst>(I)) {
+        insertCallSiteStore(RI, -1, CallSite);
+      }
+  }
+
+  return true;
+}
+
 bool SjLjEHPass::runOnFunction(Function &F) {
-  bool Res = insertSjLjEHSupport(F);
+  bool Res = false;
+  if (!DisableOldSjLjEH)
+    Res = insertSjLjEHSupport(F);
+  else
+    Res = setupEntryBlockAndCallSites(F);
   return Res;
 }