d/freebsd-nq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Revert r258455 for now, as it apparently causes miscompilation in some

Browse Source 
situations.  Until this is fully resolved, the X.org workaround in ports
still needs to take place.
This commit is contained in:
Dimitry Andric 2013-11-22 17:54:53 +00:00
parent 7b7d8599fe
commit 56510193f0
1 changed files with 14 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
contrib/llvm/lib/Target/X86/X86ISelLowering.cpp
View File

@ -2449,15 +2449,21 @@ X86TargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
RegsToPass.push_back(std::make_pair(unsigned(X86::EBX),
DAG.getNode(X86ISD::GlobalBaseReg, DebugLoc(), getPointerTy())));
} else {
// If we are tail calling a global or external symbol in GOT pic mode, we
// cannot use a direct jump, since that would make lazy dynamic linking
// impossible (see PR15086). So pretend this is not a tail call, to
// prevent the optimization to a jump.
// If we are tail calling and generating PIC/GOT style code load the
// address of the callee into ECX. The value in ecx is used as target of
// the tail jump. This is done to circumvent the ebx/callee-saved problem
// for tail calls on PIC/GOT architectures. Normally we would just put the
// address of GOT into ebx and then call target@PLT. But for tail calls
// ebx would be restored (since ebx is callee saved) before jumping to the
// target@PLT.
// Note: The actual moving to ECX is done further down.
GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee);
if ((G && !G->getGlobal()->hasHiddenVisibility() &&
!G->getGlobal()->hasProtectedVisibility()) ||
isa<ExternalSymbolSDNode>(Callee))
isTailCall = false;
if (G && !G->getGlobal()->hasHiddenVisibility() &&
!G->getGlobal()->hasProtectedVisibility())
Callee = LowerGlobalAddress(Callee, DAG);
else if (isa<ExternalSymbolSDNode>(Callee))
Callee = LowerExternalSymbol(Callee, DAG);
}
}