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Revert r195318 as it causes miscompilation (PR18029)

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195439 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Kostya Serebryany 2013-11-22 10:30:39 +00:00
parent dd254ea7cb
commit a7e8d6581f
3 changed files with 20 additions and 12 deletions
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22
lib/Target/X86/X86ISelLowering.cpp
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@ -2665,15 +2665,21 @@ X86TargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
RegsToPass.push_back(std::make_pair(unsigned(X86::EBX),
DAG.getNode(X86ISD::GlobalBaseReg, SDLoc(), 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);
}
}

6
test/CodeGen/X86/tail-call-got.ll
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@ -5,7 +5,8 @@ target triple = "i386-unknown-freebsd9.0"
define double @test1(double %x) nounwind readnone {
; CHECK-LABEL: test1:
; CHECK: calll foo@PLT
; CHECK: movl foo@GOT
; CHECK-NEXT: jmpl
%1 = tail call double @foo(double %x) nounwind readnone
ret double %1
}
@ -14,7 +15,8 @@ declare double @foo(double) readnone
define double @test2(double %x) nounwind readnone {
; CHECK-LABEL: test2:
; CHECK: calll sin@PLT
; CHECK: movl sin@GOT
; CHECK-NEXT: jmpl
%1 = tail call double @sin(double %x) nounwind readnone
ret double %1
}

4
test/CodeGen/X86/tailcallpic2.ll
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@ -9,7 +9,7 @@ define fastcc i32 @tailcaller(i32 %in1, i32 %in2) {
entry:
%tmp11 = tail call fastcc i32 @tailcallee( i32 %in1, i32 %in2, i32 %in1, i32 %in2 ) ; <i32> [#uses=1]
ret i32 %tmp11
; Note that this call via PLT could be further optimized into a direct call (no GOT, no PLT):
; CHECK: calll tailcallee@PLT
; CHECK: movl tailcallee@GOT
; CHECK: jmpl
}