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Do not do tail calls to external symbols. If the

Browse Source 
branch turns out to be ARM-to-Thumb or vice versa
the linker cannot resolve this.  8120438.

If this optimization is going to be useful we probably
need a compiler flag "assume callees are same architecture"
or something like that.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106662 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen 2010-06-23 18:52:34 +00:00
parent 151d26d15d
commit e39fdbe118
1 changed files with 9 additions and 12 deletions
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21
lib/Target/ARM/ARMISelLowering.cpp
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@ -1408,29 +1408,26 @@ ARMTargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
if (isCalleeStructRet || isCallerStructRet)
return false;
// FIXME: Completely disable sibcal for Thumb1 since Thumb1RegisterInfo::
// FIXME: Completely disable sibcall for Thumb1 since Thumb1RegisterInfo::
// emitEpilogue is not ready for them.
if (Subtarget->isThumb1Only())
return false;
// For the moment, we can only do this to functions defined in this
// compilation, or to indirect calls. A Thumb B to an ARM function,
// or vice versa, is not easily fixed up in the linker unlike BL.
// (We could do this by loading the address of the callee into a register;
// that is an extra instruction over the direct call and burns a register
// as well, so is not likely to be a win.)
if (isa<ExternalSymbolSDNode>(Callee))
return false;
if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
if (Subtarget->isThumb1Only())
const GlobalValue *GV = G->getGlobal();
if (GV->isDeclaration() || GV->isWeakForLinker())
return false;
// On Thumb, for the moment, we can only do this to functions defined in this
// compilation, or to indirect calls. A Thumb B to an ARM function is not
// easily fixed up in the linker, unlike BL.
if (Subtarget->isThumb()) {
const GlobalValue *GV = G->getGlobal();
if (GV->isDeclaration() || GV->isWeakForLinker())
return false;
}
}
// If the calling conventions do not match, then we'd better make sure the
// results are returned in the same way as what the caller expects.
if (!CCMatch) {