From 86809ccdaddf48a87ed772bc01464812caaf4baf Mon Sep 17 00:00:00 2001 From: Evan Cheng Date: Wed, 3 Feb 2010 03:28:02 +0000 Subject: Allow all types of callee's to be tail called. But avoid automatic tailcall if the callee is a result of bitcast to avoid losing necessary zext / sext etc. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95195 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp') diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index 284b984f0a..495418d999 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -4197,8 +4197,9 @@ SelectionDAGBuilder::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) { /// /// This function only tests target-independent requirements. static bool -isInTailCallPosition(const Instruction *I, Attributes CalleeRetAttr, +isInTailCallPosition(CallSite CS, Attributes CalleeRetAttr, const TargetLowering &TLI) { + const Instruction *I = CS.getInstruction(); const BasicBlock *ExitBB = I->getParent(); const TerminatorInst *Term = ExitBB->getTerminator(); const ReturnInst *Ret = dyn_cast(Term); @@ -4207,6 +4208,12 @@ isInTailCallPosition(const Instruction *I, Attributes CalleeRetAttr, // The block must end in a return statement or an unreachable. if (!Ret && !isa(Term)) return false; + // Unless we are explicitly forcing tailcall optimization do not tailcall if + // the called function is bitcast'ed. The analysis may not be entirely + // accurate. + if (!PerformTailCallOpt && isa(CS.getCalledValue())) + return false; + // If I will have a chain, make sure no other instruction that will have a // chain interposes between I and the return. if (I->mayHaveSideEffects() || I->mayReadFromMemory() || @@ -4348,9 +4355,7 @@ void SelectionDAGBuilder::LowerCallTo(CallSite CS, SDValue Callee, // Check if target-independent constraints permit a tail call here. // Target-dependent constraints are checked within TLI.LowerCallTo. if (isTailCall && - !isInTailCallPosition(CS.getInstruction(), - CS.getAttributes().getRetAttributes(), - TLI)) + !isInTailCallPosition(CS, CS.getAttributes().getRetAttributes(), TLI)) isTailCall = false; std::pair Result = -- cgit v1.2.3-18-g5258