From 74bab7f597b24d847175f8550002d8a014f63c8c Mon Sep 17 00:00:00 2001 From: Chad Rosier Date: Fri, 2 Mar 2012 02:50:46 +0000 Subject: Prevent obscure and incorrect tail-call optimization. In this instance we are generating the tail-call during legalizeDAG. The 2nd floor call can't be a tail call because it clobbers %xmm1, which is defined by the first floor call. The first floor call can't be a tail-call because it's not in the tail position. The only reasonable way I could think to fix this in a target-independent manner was to check for glue logic on the copy reg. rdar://10930395 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151877 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/X86/X86ISelLowering.cpp | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'lib') diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp index 4ad179ead6..d1ded33384 100644 --- a/lib/Target/X86/X86ISelLowering.cpp +++ b/lib/Target/X86/X86ISelLowering.cpp @@ -1589,6 +1589,11 @@ bool X86TargetLowering::isUsedByReturnOnly(SDNode *N) const { Copy->getOpcode() != ISD::FP_EXTEND) return false; + // If anything is glued to the copy, then we can't safely perform a tail call. + if (Copy->getOpcode() == ISD::CopyToReg && + Copy->getNumOperands() == 4) + return false; + bool HasRet = false; for (SDNode::use_iterator UI = Copy->use_begin(), UE = Copy->use_end(); UI != UE; ++UI) { -- cgit v1.2.3-18-g5258