Update the saved stack pointer in the sjlj function context following either

an alloca() or an llvm.stackrestore(). rdar://8031573



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104900 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 50 insertions, 14 deletions

diff --git a/lib/CodeGen/SjLjEHPrepare.cpp b/lib/CodeGen/SjLjEHPrepare.cpp
index 059e8d6..ce50568 100644
--- a/lib/CodeGen/SjLjEHPrepare.cpp
+++ b/lib/CodeGen/SjLjEHPrepare.cpp
@@ -46,6 +46,8 @@ namespace {
     Constant *UnregisterFn;
     Constant *BuiltinSetjmpFn;
     Constant *FrameAddrFn;
+    Constant *StackAddrFn;
+    Constant *StackRestoreFn;
     Constant *LSDAAddrFn;
     Value *PersonalityFn;
     Constant *SelectorFn;
@@ -107,6 +109,8 @@ bool SjLjEHPass::doInitialization(Module &M) {
                           PointerType::getUnqual(FunctionContextTy),
                           (Type *)0);
   FrameAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::frameaddress);
+  StackAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::stacksave);
+  StackRestoreFn = Intrinsic::getDeclaration(&M, Intrinsic::stackrestore);
   BuiltinSetjmpFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setjmp);
   LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda);
   SelectorFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector);
@@ -294,14 +298,22 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
   // If we don't have any invokes or unwinds, there's nothing to do.
   if (Unwinds.empty() && Invokes.empty()) return false;
 
-  // Find the eh.selector.*  and eh.exception calls. We'll use the first
-  // eh.selector to determine the right personality function to use. For
-  // SJLJ, we always use the same personality for the whole function,
-  // not on a per-selector basis.
+  // Find the eh.selector.*, eh.exception and alloca calls.
+  //
+  // Remember any allocas() that aren't in the entry block, as the
+  // jmpbuf saved SP will need to be updated for them.
+  //
+  // We'll use the first eh.selector to determine the right personality
+  // function to use. For SJLJ, we always use the same personality for the
+  // whole function, not on a per-selector basis.
   // FIXME: That's a bit ugly. Better way?
   SmallVector<CallInst*,16> EH_Selectors;
   SmallVector<CallInst*,16> EH_Exceptions;
-  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+  SmallVector<Instruction*,16> JmpbufUpdatePoints;
+  // Note: Skip the entry block since there's nothing there that interests
+  // us. eh.selector and eh.exception shouldn't ever be there, and we
+  // want to disregard any allocas that are there.
+  for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;) {
     for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
       if (CallInst *CI = dyn_cast<CallInst>(I)) {
         if (CI->getCalledFunction() == SelectorFn) {
@@ -309,7 +321,11 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
           EH_Selectors.push_back(CI);
         } else if (CI->getCalledFunction() == ExceptionFn) {
           EH_Exceptions.push_back(CI);
+        } else if (CI->getCalledFunction() == StackRestoreFn) {
+          JmpbufUpdatePoints.push_back(CI);
         }
+      } else if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
+        JmpbufUpdatePoints.push_back(AI);
       }
     }
   }
@@ -419,7 +435,7 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
     // Populate the Function Context
     //   1. LSDA address
     //   2. Personality function address
-    //   3. jmpbuf (save FP and call eh.sjlj.setjmp)
+    //   3. jmpbuf (save SP, FP and call eh.sjlj.setjmp)
 
     // LSDA address
     Idxs[0] = Zero;
@@ -440,31 +456,41 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
     new StoreInst(PersonalityFn, PersonalityFieldPtr, true,
                   EntryBB->getTerminator());
 
-    //   Save the frame pointer.
+    // Save the frame pointer.
     Idxs[1] = ConstantInt::get(Int32Ty, 5);
-    Value *FieldPtr
+    Value *JBufPtr
       = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2,
                                   "jbuf_gep",
                                   EntryBB->getTerminator());
     Idxs[1] = ConstantInt::get(Int32Ty, 0);
-    Value *ElemPtr =
-      GetElementPtrInst::Create(FieldPtr, Idxs, Idxs+2, "jbuf_fp_gep",
+    Value *FramePtr =
+      GetElementPtrInst::Create(JBufPtr, Idxs, Idxs+2, "jbuf_fp_gep",
                                 EntryBB->getTerminator());
 
     Value *Val = CallInst::Create(FrameAddrFn,
                                   ConstantInt::get(Int32Ty, 0),
                                   "fp",
                                   EntryBB->getTerminator());
-    new StoreInst(Val, ElemPtr, true, EntryBB->getTerminator());
-    // Call the setjmp instrinsic. It fills in the rest of the jmpbuf
+    new StoreInst(Val, FramePtr, true, EntryBB->getTerminator());
+
+    // Save the stack pointer.
+    Idxs[1] = ConstantInt::get(Int32Ty, 2);
+    Value *StackPtr =
+      GetElementPtrInst::Create(JBufPtr, Idxs, Idxs+2, "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, FieldPtr,
+      CastInst::Create(Instruction::BitCast, JBufPtr,
                        Type::getInt8PtrTy(F.getContext()), "",
                        EntryBB->getTerminator());
     Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg,
                                           "dispatch",
                                           EntryBB->getTerminator());
-    // check the return value of the setjmp. non-zero goes to dispatcher
+    // check the return value of the setjmp. non-zero goes to dispatcher.
     Value *IsNormal = new ICmpInst(EntryBB->getTerminator(),
                                    ICmpInst::ICMP_EQ, DispatchVal, Zero,
                                    "notunwind");
@@ -509,6 +535,16 @@ bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
       Unwinds[i]->eraseFromParent();
     }
 
+    // Following any allocas not in the entry block, update the saved SP
+    // in the jmpbuf to the new value.
+    for (unsigned i = 0, e = JmpbufUpdatePoints.size(); i != e; ++i) {
+      Instruction *AI = JmpbufUpdatePoints[i];
+      Instruction *StackAddr = CallInst::Create(StackAddrFn, "sp");
+      StackAddr->insertAfter(AI);
+      Instruction *StoreStackAddr = new StoreInst(StackAddr, StackPtr, true);
+      StoreStackAddr->insertAfter(StackAddr);
+    }
+
     // Finally, for any returns from this function, if this function contains an
     // invoke, add a call to unregister the function context.
     for (unsigned i = 0, e = Returns.size(); i != e; ++i)