Vendor import of clang trunk r130700:

http://llvm.org/svn/llvm-project/cfe/trunk@130700

1 files changed, 342 insertions, 18 deletions

diff --git a/lib/CodeGen/CGStmt.cpp b/lib/CodeGen/CGStmt.cpp
index cd23811..99bc3f4 100644
--- a/lib/CodeGen/CGStmt.cpp
+++ b/lib/CodeGen/CGStmt.cpp
@@ -72,6 +72,8 @@ void CodeGenFunction::EmitStmt(const Stmt *S) {
   switch (S->getStmtClass()) {
   case Stmt::NoStmtClass:
   case Stmt::CXXCatchStmtClass:
+  case Stmt::SEHExceptStmtClass:
+  case Stmt::SEHFinallyStmtClass:
     llvm_unreachable("invalid statement class to emit generically");
   case Stmt::NullStmtClass:
   case Stmt::CompoundStmtClass:
@@ -153,6 +155,11 @@ void CodeGenFunction::EmitStmt(const Stmt *S) {
   case Stmt::CXXTryStmtClass:
     EmitCXXTryStmt(cast<CXXTryStmt>(*S));
     break;
+  case Stmt::CXXForRangeStmtClass:
+    EmitCXXForRangeStmt(cast<CXXForRangeStmt>(*S));
+  case Stmt::SEHTryStmtClass:
+    // FIXME Not yet implemented
+    break;
   }
 }
 
@@ -359,10 +366,12 @@ void CodeGenFunction::EmitIfStmt(const IfStmt &S) {
 
   // If the condition constant folds and can be elided, try to avoid emitting
   // the condition and the dead arm of the if/else.
-  if (int Cond = ConstantFoldsToSimpleInteger(S.getCond())) {
+  bool CondConstant;
+  if (ConstantFoldsToSimpleInteger(S.getCond(), CondConstant)) {
     // Figure out which block (then or else) is executed.
-    const Stmt *Executed = S.getThen(), *Skipped  = S.getElse();
-    if (Cond == -1)  // Condition false?
+    const Stmt *Executed = S.getThen();
+    const Stmt *Skipped  = S.getElse();
+    if (!CondConstant)  // Condition false?
       std::swap(Executed, Skipped);
 
     // If the skipped block has no labels in it, just emit the executed block.
@@ -395,11 +404,17 @@ void CodeGenFunction::EmitIfStmt(const IfStmt &S) {
 
   // Emit the 'else' code if present.
   if (const Stmt *Else = S.getElse()) {
+    // There is no need to emit line number for unconditional branch.
+    if (getDebugInfo())
+      Builder.SetCurrentDebugLocation(llvm::DebugLoc());
     EmitBlock(ElseBlock);
     {
       RunCleanupsScope ElseScope(*this);
       EmitStmt(Else);
     }
+    // There is no need to emit line number for unconditional branch.
+    if (getDebugInfo())
+      Builder.SetCurrentDebugLocation(llvm::DebugLoc());
     EmitBranch(ContBlock);
   }
 
@@ -628,6 +643,80 @@ void CodeGenFunction::EmitForStmt(const ForStmt &S) {
   EmitBlock(LoopExit.getBlock(), true);
 }
 
+void CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S) {
+  JumpDest LoopExit = getJumpDestInCurrentScope("for.end");
+
+  RunCleanupsScope ForScope(*this);
+
+  CGDebugInfo *DI = getDebugInfo();
+  if (DI) {
+    DI->setLocation(S.getSourceRange().getBegin());
+    DI->EmitRegionStart(Builder);
+  }
+
+  // Evaluate the first pieces before the loop.
+  EmitStmt(S.getRangeStmt());
+  EmitStmt(S.getBeginEndStmt());
+
+  // Start the loop with a block that tests the condition.
+  // If there's an increment, the continue scope will be overwritten
+  // later.
+  llvm::BasicBlock *CondBlock = createBasicBlock("for.cond");
+  EmitBlock(CondBlock);
+
+  // If there are any cleanups between here and the loop-exit scope,
+  // create a block to stage a loop exit along.
+  llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
+  if (ForScope.requiresCleanups())
+    ExitBlock = createBasicBlock("for.cond.cleanup");
+  
+  // The loop body, consisting of the specified body and the loop variable.
+  llvm::BasicBlock *ForBody = createBasicBlock("for.body");
+
+  // The body is executed if the expression, contextually converted
+  // to bool, is true.
+  llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
+  Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock);
+
+  if (ExitBlock != LoopExit.getBlock()) {
+    EmitBlock(ExitBlock);
+    EmitBranchThroughCleanup(LoopExit);
+  }
+
+  EmitBlock(ForBody);
+
+  // Create a block for the increment. In case of a 'continue', we jump there.
+  JumpDest Continue = getJumpDestInCurrentScope("for.inc");
+
+  // Store the blocks to use for break and continue.
+  BreakContinueStack.push_back(BreakContinue(LoopExit, Continue));
+
+  {
+    // Create a separate cleanup scope for the loop variable and body.
+    RunCleanupsScope BodyScope(*this);
+    EmitStmt(S.getLoopVarStmt());
+    EmitStmt(S.getBody());
+  }
+
+  // If there is an increment, emit it next.
+  EmitBlock(Continue.getBlock());
+  EmitStmt(S.getInc());
+
+  BreakContinueStack.pop_back();
+
+  EmitBranch(CondBlock);
+
+  ForScope.ForceCleanup();
+
+  if (DI) {
+    DI->setLocation(S.getSourceRange().getEnd());
+    DI->EmitRegionEnd(Builder);
+  }
+
+  // Emit the fall-through block.
+  EmitBlock(LoopExit.getBlock(), true);
+}
+
 void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) {
   if (RV.isScalar()) {
     Builder.CreateStore(RV.getScalarVal(), ReturnValue);
@@ -745,8 +834,7 @@ void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) {
   if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) {
     // Range is small enough to add multiple switch instruction cases.
     for (unsigned i = 0, e = Range.getZExtValue() + 1; i != e; ++i) {
-      SwitchInsn->addCase(llvm::ConstantInt::get(getLLVMContext(), LHS),
-                          CaseDest);
+      SwitchInsn->addCase(Builder.getInt(LHS), CaseDest);
       LHS++;
     }
     return;
@@ -767,11 +855,9 @@ void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) {
 
   // Emit range check.
   llvm::Value *Diff =
-    Builder.CreateSub(SwitchInsn->getCondition(),
-                      llvm::ConstantInt::get(getLLVMContext(), LHS),  "tmp");
+    Builder.CreateSub(SwitchInsn->getCondition(), Builder.getInt(LHS),  "tmp");
   llvm::Value *Cond =
-    Builder.CreateICmpULE(Diff, llvm::ConstantInt::get(getLLVMContext(), Range),
-                          "inbounds");
+    Builder.CreateICmpULE(Diff, Builder.getInt(Range), "inbounds");
   Builder.CreateCondBr(Cond, CaseDest, FalseDest);
 
   // Restore the appropriate insertion point.
@@ -782,16 +868,37 @@ void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) {
 }
 
 void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) {
+  // Handle case ranges.
   if (S.getRHS()) {
     EmitCaseStmtRange(S);
     return;
   }
 
+  llvm::ConstantInt *CaseVal =
+    Builder.getInt(S.getLHS()->EvaluateAsInt(getContext()));
+
+  // If the body of the case is just a 'break', and if there was no fallthrough,
+  // try to not emit an empty block.
+  if (isa<BreakStmt>(S.getSubStmt())) {
+    JumpDest Block = BreakContinueStack.back().BreakBlock;
+    
+    // Only do this optimization if there are no cleanups that need emitting.
+    if (isObviouslyBranchWithoutCleanups(Block)) {
+      SwitchInsn->addCase(CaseVal, Block.getBlock());
+
+      // If there was a fallthrough into this case, make sure to redirect it to
+      // the end of the switch as well.
+      if (Builder.GetInsertBlock()) {
+        Builder.CreateBr(Block.getBlock());
+        Builder.ClearInsertionPoint();
+      }
+      return;
+    }
+  }
+  
   EmitBlock(createBasicBlock("sw.bb"));
   llvm::BasicBlock *CaseDest = Builder.GetInsertBlock();
-  llvm::APSInt CaseVal = S.getLHS()->EvaluateAsInt(getContext());
-  SwitchInsn->addCase(llvm::ConstantInt::get(getLLVMContext(), CaseVal),
-                      CaseDest);
+  SwitchInsn->addCase(CaseVal, CaseDest);
 
   // Recursively emitting the statement is acceptable, but is not wonderful for
   // code where we have many case statements nested together, i.e.:
@@ -805,13 +912,12 @@ void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) {
   const CaseStmt *CurCase = &S;
   const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt());
 
-  // Otherwise, iteratively add consequtive cases to this switch stmt.
+  // Otherwise, iteratively add consecutive cases to this switch stmt.
   while (NextCase && NextCase->getRHS() == 0) {
     CurCase = NextCase;
-    CaseVal = CurCase->getLHS()->EvaluateAsInt(getContext());
-    SwitchInsn->addCase(llvm::ConstantInt::get(getLLVMContext(), CaseVal),
-                        CaseDest);
-
+    llvm::ConstantInt *CaseVal = 
+      Builder.getInt(CurCase->getLHS()->EvaluateAsInt(getContext()));
+    SwitchInsn->addCase(CaseVal, CaseDest);
     NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt());
   }
 
@@ -827,6 +933,207 @@ void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) {
   EmitStmt(S.getSubStmt());
 }
 
+/// CollectStatementsForCase - Given the body of a 'switch' statement and a
+/// constant value that is being switched on, see if we can dead code eliminate
+/// the body of the switch to a simple series of statements to emit.  Basically,
+/// on a switch (5) we want to find these statements:
+///    case 5:
+///      printf(...);    <--
+///      ++i;            <--
+///      break;
+///
+/// and add them to the ResultStmts vector.  If it is unsafe to do this
+/// transformation (for example, one of the elided statements contains a label
+/// that might be jumped to), return CSFC_Failure.  If we handled it and 'S'
+/// should include statements after it (e.g. the printf() line is a substmt of
+/// the case) then return CSFC_FallThrough.  If we handled it and found a break
+/// statement, then return CSFC_Success.
+///
+/// If Case is non-null, then we are looking for the specified case, checking
+/// that nothing we jump over contains labels.  If Case is null, then we found
+/// the case and are looking for the break.
+///
+/// If the recursive walk actually finds our Case, then we set FoundCase to
+/// true.
+///
+enum CSFC_Result { CSFC_Failure, CSFC_FallThrough, CSFC_Success };
+static CSFC_Result CollectStatementsForCase(const Stmt *S,
+                                            const SwitchCase *Case,
+                                            bool &FoundCase,
+                              llvm::SmallVectorImpl<const Stmt*> &ResultStmts) {
+  // If this is a null statement, just succeed.
+  if (S == 0)
+    return Case ? CSFC_Success : CSFC_FallThrough;
+    
+  // If this is the switchcase (case 4: or default) that we're looking for, then
+  // we're in business.  Just add the substatement.
+  if (const SwitchCase *SC = dyn_cast<SwitchCase>(S)) {
+    if (S == Case) {
+      FoundCase = true;
+      return CollectStatementsForCase(SC->getSubStmt(), 0, FoundCase,
+                                      ResultStmts);
+    }
+    
+    // Otherwise, this is some other case or default statement, just ignore it.
+    return CollectStatementsForCase(SC->getSubStmt(), Case, FoundCase,
+                                    ResultStmts);
+  }
+
+  // If we are in the live part of the code and we found our break statement,
+  // return a success!
+  if (Case == 0 && isa<BreakStmt>(S))
+    return CSFC_Success;
+  
+  // If this is a switch statement, then it might contain the SwitchCase, the
+  // break, or neither.
+  if (const CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) {
+    // Handle this as two cases: we might be looking for the SwitchCase (if so
+    // the skipped statements must be skippable) or we might already have it.
+    CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end();
+    if (Case) {
+      // Keep track of whether we see a skipped declaration.  The code could be
+      // using the declaration even if it is skipped, so we can't optimize out
+      // the decl if the kept statements might refer to it.
+      bool HadSkippedDecl = false;
+      
+      // If we're looking for the case, just see if we can skip each of the
+      // substatements.
+      for (; Case && I != E; ++I) {
+        HadSkippedDecl |= isa<DeclStmt>(I);
+        
+        switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) {
+        case CSFC_Failure: return CSFC_Failure;
+        case CSFC_Success:
+          // A successful result means that either 1) that the statement doesn't
+          // have the case and is skippable, or 2) does contain the case value
+          // and also contains the break to exit the switch.  In the later case,
+          // we just verify the rest of the statements are elidable.
+          if (FoundCase) {
+            // If we found the case and skipped declarations, we can't do the
+            // optimization.
+            if (HadSkippedDecl)
+              return CSFC_Failure;
+            
+            for (++I; I != E; ++I)
+              if (CodeGenFunction::ContainsLabel(*I, true))
+                return CSFC_Failure;
+            return CSFC_Success;
+          }
+          break;
+        case CSFC_FallThrough:
+          // If we have a fallthrough condition, then we must have found the
+          // case started to include statements.  Consider the rest of the
+          // statements in the compound statement as candidates for inclusion.
+          assert(FoundCase && "Didn't find case but returned fallthrough?");
+          // We recursively found Case, so we're not looking for it anymore.
+          Case = 0;
+            
+          // If we found the case and skipped declarations, we can't do the
+          // optimization.
+          if (HadSkippedDecl)
+            return CSFC_Failure;
+          break;
+        }
+      }
+    }
+
+    // If we have statements in our range, then we know that the statements are
+    // live and need to be added to the set of statements we're tracking.
+    for (; I != E; ++I) {
+      switch (CollectStatementsForCase(*I, 0, FoundCase, ResultStmts)) {
+      case CSFC_Failure: return CSFC_Failure;
+      case CSFC_FallThrough:
+        // A fallthrough result means that the statement was simple and just
+        // included in ResultStmt, keep adding them afterwards.
+        break;
+      case CSFC_Success:
+        // A successful result means that we found the break statement and
+        // stopped statement inclusion.  We just ensure that any leftover stmts
+        // are skippable and return success ourselves.
+        for (++I; I != E; ++I)
+          if (CodeGenFunction::ContainsLabel(*I, true))
+            return CSFC_Failure;
+        return CSFC_Success;
+      }      
+    }
+    
+    return Case ? CSFC_Success : CSFC_FallThrough;
+  }
+
+  // Okay, this is some other statement that we don't handle explicitly, like a
+  // for statement or increment etc.  If we are skipping over this statement,
+  // just verify it doesn't have labels, which would make it invalid to elide.
+  if (Case) {
+    if (CodeGenFunction::ContainsLabel(S, true))
+      return CSFC_Failure;
+    return CSFC_Success;
+  }
+  
+  // Otherwise, we want to include this statement.  Everything is cool with that
+  // so long as it doesn't contain a break out of the switch we're in.
+  if (CodeGenFunction::containsBreak(S)) return CSFC_Failure;
+  
+  // Otherwise, everything is great.  Include the statement and tell the caller
+  // that we fall through and include the next statement as well.
+  ResultStmts.push_back(S);
+  return CSFC_FallThrough;
+}
+
+/// FindCaseStatementsForValue - Find the case statement being jumped to and
+/// then invoke CollectStatementsForCase to find the list of statements to emit
+/// for a switch on constant.  See the comment above CollectStatementsForCase
+/// for more details.
+static bool FindCaseStatementsForValue(const SwitchStmt &S,
+                                       const llvm::APInt &ConstantCondValue,
+                                llvm::SmallVectorImpl<const Stmt*> &ResultStmts,
+                                       ASTContext &C) {
+  // First step, find the switch case that is being branched to.  We can do this
+  // efficiently by scanning the SwitchCase list.
+  const SwitchCase *Case = S.getSwitchCaseList();
+  const DefaultStmt *DefaultCase = 0;
+  
+  for (; Case; Case = Case->getNextSwitchCase()) {
+    // It's either a default or case.  Just remember the default statement in
+    // case we're not jumping to any numbered cases.
+    if (const DefaultStmt *DS = dyn_cast<DefaultStmt>(Case)) {
+      DefaultCase = DS;
+      continue;
+    }
+    
+    // Check to see if this case is the one we're looking for.
+    const CaseStmt *CS = cast<CaseStmt>(Case);
+    // Don't handle case ranges yet.
+    if (CS->getRHS()) return false;
+    
+    // If we found our case, remember it as 'case'.
+    if (CS->getLHS()->EvaluateAsInt(C) == ConstantCondValue)
+      break;
+  }
+  
+  // If we didn't find a matching case, we use a default if it exists, or we
+  // elide the whole switch body!
+  if (Case == 0) {
+    // It is safe to elide the body of the switch if it doesn't contain labels
+    // etc.  If it is safe, return successfully with an empty ResultStmts list.
+    if (DefaultCase == 0)
+      return !CodeGenFunction::ContainsLabel(&S);
+    Case = DefaultCase;
+  }
+
+  // Ok, we know which case is being jumped to, try to collect all the
+  // statements that follow it.  This can fail for a variety of reasons.  Also,
+  // check to see that the recursive walk actually found our case statement.
+  // Insane cases like this can fail to find it in the recursive walk since we
+  // don't handle every stmt kind:
+  // switch (4) {
+  //   while (1) {
+  //     case 4: ...
+  bool FoundCase = false;
+  return CollectStatementsForCase(S.getBody(), Case, FoundCase,
+                                  ResultStmts) != CSFC_Failure &&
+         FoundCase;
+}
+
 void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
   JumpDest SwitchExit = getJumpDestInCurrentScope("sw.epilog");
 
@@ -835,6 +1142,23 @@ void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
   if (S.getConditionVariable())
     EmitAutoVarDecl(*S.getConditionVariable());
 
+  // See if we can constant fold the condition of the switch and therefore only
+  // emit the live case statement (if any) of the switch.
+  llvm::APInt ConstantCondValue;
+  if (ConstantFoldsToSimpleInteger(S.getCond(), ConstantCondValue)) {
+    llvm::SmallVector<const Stmt*, 4> CaseStmts;
+    if (FindCaseStatementsForValue(S, ConstantCondValue, CaseStmts,
+                                   getContext())) {
+      RunCleanupsScope ExecutedScope(*this);
+
+      // Okay, we can dead code eliminate everything except this case.  Emit the
+      // specified series of statements and we're good.
+      for (unsigned i = 0, e = CaseStmts.size(); i != e; ++i)
+        EmitStmt(CaseStmts[i]);
+      return;
+    }
+  }
+    
   llvm::Value *CondV = EmitScalarExpr(S.getCond());
 
   // Handle nested switch statements.
@@ -1031,7 +1355,7 @@ static llvm::MDNode *getAsmSrcLocInfo(const StringLiteral *Str,
     }
   }    
   
-  return llvm::MDNode::get(CGF.getLLVMContext(), Locs.data(), Locs.size());
+  return llvm::MDNode::get(CGF.getLLVMContext(), Locs);
 }
 
 void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {