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Prevent obscure and incorrect tail-call optimization.

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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
This commit is contained in:
Chad Rosier
2012-03-02 02:50:46 +00:00
parent b83e2bbfbc
commit 74bab7f597
2 changed files with 34 additions and 0 deletions
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5
lib/Target/X86/X86ISelLowering.cpp
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@@ -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) {