*** Implement inlining of Invoke instructions!

llvm-svn: 8106

lib/Transforms/Utils/InlineFunction.cpp

@@ -9,14 +9,17 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Constant.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/Module.h"
-#include "llvm/iTerminators.h"
+#include "llvm/Instructions.h"
-#include "llvm/iPHINode.h"
+#include "llvm/Intrinsics.h"
-#include "llvm/iMemory.h"
+#include "llvm/Support/CallSite.h"
-#include "llvm/iOther.h"
 #include "llvm/Transforms/Utils/Local.h"
 
+bool InlineFunction(CallInst *CI) { return InlineFunction(CallSite(CI)); }
+bool InlineFunction(InvokeInst *II) { return InlineFunction(CallSite(II)); }
+
 // InlineFunction - This function inlines the called function into the basic
 // block of the caller.  This returns false if it is not possible to inline this
 // call.  The program is still in a well defined state if this occurs though.
@@ -26,46 +29,60 @@
 // exists in the instruction stream.  Similiarly this will inline a recursive
 // function by one level.
 //
-bool InlineFunction(CallInst *CI) {
+bool InlineFunction(CallSite CS) {
-  assert(isa<CallInst>(CI) && "InlineFunction only works on CallInst nodes");
+  Instruction *TheCall = CS.getInstruction();
-  assert(CI->getParent() && "Instruction not embedded in basic block!");
+  assert(TheCall->getParent() && TheCall->getParent()->getParent() &&
-  assert(CI->getParent()->getParent() && "Instruction not in function!");
+         "Instruction not in function!");
 
-  const Function *CalledFunc = CI->getCalledFunction();
+  const Function *CalledFunc = CS.getCalledFunction();
   if (CalledFunc == 0 ||          // Can't inline external function or indirect
       CalledFunc->isExternal() || // call, or call to a vararg function!
       CalledFunc->getFunctionType()->isVarArg()) return false;
 
-  BasicBlock *OrigBB = CI->getParent();
+  BasicBlock *OrigBB = TheCall->getParent();
   Function *Caller = OrigBB->getParent();
 
-  // Call splitBasicBlock - The original basic block now ends at the instruction
+  // We want to clone the entire callee function into the whole between the
-  // immediately before the call.  The original basic block now ends with an
+  // "starter" and "ender" blocks.  How we accomplish this depends on whether
-  // unconditional branch to NewBB, and NewBB starts with the call instruction.
+  // this is an invoke instruction or a call instruction.
-  //
-  BasicBlock *NewBB = OrigBB->splitBasicBlock(CI,
-                                              CalledFunc->getName()+".entry");
-  NewBB->setName(OrigBB->getName()+".split");
 
-  // Remove (unlink) the CallInst from the start of the new basic block.  
+  BasicBlock *InvokeDest = 0;     // Exception handling destination
-  NewBB->getInstList().remove(CI);
+  BasicBlock *AfterCallBB;
+  if (InvokeInst *II = dyn_cast<InvokeInst>(TheCall)) {
+    AfterCallBB = II->getNormalDest();
+    InvokeDest = II->getExceptionalDest();
+
+    // Add an unconditional branch to make this look like the CallInst case...
+    new BranchInst(AfterCallBB, TheCall);
+
+    // Remove (unlink) the InvokeInst from the function...
+    OrigBB->getInstList().remove(TheCall);
+  } else {  // It's a call
+    // If this is a call instruction, we need to split the basic block that the
+    // call lives in.
+    //
+    AfterCallBB = OrigBB->splitBasicBlock(TheCall,
+                                          CalledFunc->getName()+".entry");
+    // Remove (unlink) the CallInst from the function...
+    AfterCallBB->getInstList().remove(TheCall);
+  }
 
   // If we have a return value generated by this call, convert it into a PHI 
   // node that gets values from each of the old RET instructions in the original
   // function.
   //
   PHINode *PHI = 0;
-  if (!CI->use_empty()) {
+  if (!TheCall->use_empty()) {
     // The PHI node should go at the front of the new basic block to merge all 
     // possible incoming values.
     //
-    PHI = new PHINode(CalledFunc->getReturnType(), CI->getName(),
+    PHI = new PHINode(CalledFunc->getReturnType(), TheCall->getName(),
-                      NewBB->begin());
+                      AfterCallBB->begin());
 
     // Anything that used the result of the function call should now use the PHI
     // node as their operand.
     //
-    CI->replaceAllUsesWith(PHI);
+    TheCall->replaceAllUsesWith(PHI);
   }
 
   // Get an iterator to the last basic block in the function, which will have
@@ -75,21 +92,23 @@ bool InlineFunction(CallInst *CI) {
 
   // Calculate the vector of arguments to pass into the function cloner...
   std::map<const Value*, Value*> ValueMap;
-  assert((unsigned)std::distance(CalledFunc->abegin(), CalledFunc->aend()) == 
+  assert(std::distance(CalledFunc->abegin(), CalledFunc->aend()) == 
-         CI->getNumOperands()-1 && "No varargs calls can be inlined yet!");
+         std::distance(CS.arg_begin(), CS.arg_end()) &&
+         "No varargs calls can be inlined!");
 
-  unsigned i = 1;
+  CallSite::arg_iterator AI = CS.arg_begin();
   for (Function::const_aiterator I = CalledFunc->abegin(), E=CalledFunc->aend();
-       I != E; ++I, ++i)
+       I != E; ++I, ++AI)
-    ValueMap[I] = CI->getOperand(i);
+    ValueMap[I] = *AI;
 
-  // Since we are now done with the CallInst, we can delete it.
+  // Since we are now done with the Call/Invoke, we can delete it.
-  delete CI;
+  delete TheCall;
 
   // Make a vector to capture the return instructions in the cloned function...
   std::vector<ReturnInst*> Returns;
 
   // Populate the value map with all of the globals in the program.
+  // FIXME: This should be the default for CloneFunctionInto!
   Module &M = *Caller->getParent();
   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
     ValueMap[I] = I;
@@ -105,8 +124,8 @@ bool InlineFunction(CallInst *CI) {
     ReturnInst *RI = Returns[i];
     BasicBlock *BB = RI->getParent();
 
-    // Add a branch to the merge point where the PHI node would live...
+    // Add a branch to the merge point where the PHI node lives if it exists.
-    new BranchInst(NewBB, RI);
+    new BranchInst(AfterCallBB, RI);
 
     if (PHI) {   // The PHI node should include this value!
       assert(RI->getReturnValue() && "Ret should have value!");
@@ -128,8 +147,8 @@ bool InlineFunction(CallInst *CI) {
     PHI->getParent()->getInstList().erase(PHI);
   }
 
-  // Change the branch that used to go to NewBB to branch to the first basic 
+  // Change the branch that used to go to AfterCallBB to branch to the first
-  // block of the inlined function.
+  // basic block of the inlined function.
   //
   TerminatorInst *Br = OrigBB->getTerminator();
   assert(Br && Br->getOpcode() == Instruction::Br && 
@@ -141,25 +160,93 @@ bool InlineFunction(CallInst *CI) {
   // calculate which instruction they should be inserted before.  We insert the
   // instructions at the end of the current alloca list.
   //
-  BasicBlock::iterator InsertPoint = Caller->begin()->begin();
+  if (isa<AllocaInst>(LastBlock->begin())) {
-  while (isa<AllocaInst>(InsertPoint)) ++InsertPoint;
+    BasicBlock::iterator InsertPoint = Caller->begin()->begin();
+    while (isa<AllocaInst>(InsertPoint)) ++InsertPoint;
+    
+    for (BasicBlock::iterator I = LastBlock->begin(), E = LastBlock->end();
+         I != E; )
+      if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
+        ++I;  // Move to the next instruction
+        LastBlock->getInstList().remove(AI);
+        Caller->front().getInstList().insert(InsertPoint, AI);      
+      } else {
+        ++I;
+      }
+  }
 
-  for (BasicBlock::iterator I = LastBlock->begin(), E = LastBlock->end();
+  // If we just inlined a call due to an invoke instruction, scan the inlined
-       I != E; )
+  // function checking for function calls that should now be made into invoke
-    if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
+  // instructions, and for llvm.exc.rethrow()'s which should be turned into
-      ++I;  // Move to the next instruction
+  // branches.
-      LastBlock->getInstList().remove(AI);
+  if (InvokeDest)
-      Caller->front().getInstList().insert(InsertPoint, AI);
+    for (Function::iterator BB = LastBlock, E = Caller->end(); BB != E; ++BB)
-      
+      for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
-    } else {
+        // We only need to check for function calls: inlined invoke instructions
-      ++I;
+        // require no special handling...
-    }
+        if (CallInst *CI = dyn_cast<CallInst>(I)) {
+          // FIXME: this should use annotations of the LLVM functions themselves
+          // to determine whether or not the function can throw.
+          bool ShouldInvokify = true;
+          
+          if (Function *F = CI->getCalledFunction())
+            if (unsigned ID = F->getIntrinsicID())
+              if (ID == LLVMIntrinsic::exc_rethrow) {
+                // llvm.exc.rethrow requires special handling when it gets
+                // inlined into an invoke site.  Once this happens, we know that
+                // the rethrow would cause a control transfer to the invoke
+                // exception destination, so we can transform it into a direct
+                // branch to the exception destination.
+                BranchInst *BI = new BranchInst(InvokeDest, CI);
+
+                // Note that since any instructions after the rethrow/branch are
+                // dead, we must delete them now (otherwise the terminator we
+                // just inserted wouldn't be at the end of the basic block!)
+                BasicBlock *CurBB = BB;
+                while (&CurBB->back() != BI) {
+                  Instruction *I = &CurBB->back();
+                  if (!I->use_empty())
+                    I->replaceAllUsesWith(Constant::getNullValue(I->getType()));
+                  CurBB->getInstList().pop_back();
+                }
+
+                break;  // Done with this basic block!
+              } else if (ID == LLVMIntrinsic::exc_throw ||
+                         ID == LLVMIntrinsic::exc_getcurrent) {
+                ShouldInvokify = false; // Not correct to invokify exc.throw!
+              }
+          
+          // If we should convert this function into an invoke instruction, do
+          // so now.
+          if (ShouldInvokify) {
+            // First, split the basic block...
+            BasicBlock *Split = BB->splitBasicBlock(CI, CI->getName()+".noexc");
+            
+            // Next, create the new invoke instruction, inserting it at the end
+            // of the old basic block.
+            new InvokeInst(CI->getCalledValue(), Split, InvokeDest, 
+                           std::vector<Value*>(CI->op_begin()+1, CI->op_end()),
+                           CI->getName(), BB->getTerminator());
+
+            // Delete the unconditional branch inserted by splitBasicBlock
+            BB->getInstList().pop_back();
+            Split->getInstList().pop_front();  // Delete the original call
+            
+            // This basic block is now complete, start scanning the next one.
+            break;
+          } else {
+            ++I;
+          }
+        } else {
+          ++I;
+        }
+      }
 
   // Now that the function is correct, make it a little bit nicer.  In
   // particular, move the basic blocks inserted from the end of the function
   // into the space made by splitting the source basic block.
   //
-  Caller->getBasicBlockList().splice(NewBB, Caller->getBasicBlockList(), 
+  Caller->getBasicBlockList().splice(AfterCallBB, Caller->getBasicBlockList(), 
                                      LastBlock, Caller->end());
 
   // We should always be able to fold the entry block of the function into the
@@ -170,8 +257,8 @@ bool InlineFunction(CallInst *CI) {
   
   // Okay, continue the CFG cleanup.  It's often the case that there is only a
   // single return instruction in the callee function.  If this is the case,
-  // then we have an unconditional branch from the return block to the 'NewBB'.
+  // then we have an unconditional branch from the return block to the
-  // Check for this case, and eliminate the branch is possible.
+  // 'AfterCallBB'.  Check for this case, and eliminate the branch is possible.
-  SimplifyCFG(NewBB);
+  SimplifyCFG(AfterCallBB);
   return true;
 }