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Avoid recursive sibcall's.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94946 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2010-01-31 06:44:49 +00:00
parent 1144d7e3cc
commit 843bd699f6
2 changed files with 44 additions and 6 deletions
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26
lib/Target/X86/X86ISelLowering.cpp
View File

@ -2252,10 +2252,26 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
// If -tailcallopt is specified, make fastcc functions tail-callable.
const Function *CallerF = DAG.getMachineFunction().getFunction();
if (PerformTailCallOpt &&
CalleeCC == CallingConv::Fast &&
CallerF->getCallingConv() == CalleeCC)
return true;
if (PerformTailCallOpt) {
if (CalleeCC == CallingConv::Fast &&
CallerF->getCallingConv() == CalleeCC)
return true;
return false;
}
// Do not tail call optimize vararg calls for now.
if (isVarArg)
return false;
// Don't tail call optimize recursive call.
GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee);
const Function *CalleeF = G ? cast<Function>(G->getGlobal()) : 0;
if (CallerF == CalleeF)
return false;
// If it's an indirect call, conversatively return false if the caller's
// address is taken.
if (!isa<ExternalSymbolSDNode>(Callee) && CallerF->hasAddressTaken())
return false;
// Look for obvious safe cases to perform tail call optimization.
// If the callee takes no arguments then go on to check the results of the
@ -2279,9 +2295,7 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
return true;
// If the return types match, then it's safe.
GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee);
if (!G) return false; // FIXME: common external symbols?
Function *CalleeF = cast<Function>(G->getGlobal());
const Type *CalleeRetTy = CalleeF->getReturnType();
return CallerRetTy == CalleeRetTy;
}

24
test/CodeGen/X86/tailcall2.ll
View File

@ -65,3 +65,27 @@ entry:
tail call void %x() nounwind
ret void
}
define i32 @t6(i32 %x) nounwind ssp {
entry:
; 32: t6:
; 32: call {{_?}}t6
; 32: call {{_?}}bar
; 64: t6:
; 64: callq {{_?}}t6
; 64: jmp {{_?}}bar
%0 = icmp slt i32 %x, 10
br i1 %0, label %bb, label %bb1
bb:
%1 = add nsw i32 %x, -1
%2 = tail call i32 @t6(i32 %1) nounwind ssp
ret i32 %2
bb1:
%3 = tail call i32 @bar(i32 %x) nounwind
ret i32 %3
}
declare i32 @bar(i32)