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llvm/lib/Target/ARM/ARMISelLowering.cpp
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| Show First 20 Lines • Show All 2,946 Lines • ▼ Show 20 Lines | bool ARMTargetLowering::IsEligibleForTailCallOptimization( | ||||
| const Function &CallerF = MF.getFunction(); | const Function &CallerF = MF.getFunction(); | ||||
| CallingConv::ID CallerCC = CallerF.getCallingConv(); | CallingConv::ID CallerCC = CallerF.getCallingConv(); | ||||
| assert(Subtarget->supportsTailCall()); | assert(Subtarget->supportsTailCall()); | ||||
| // Indirect tail calls cannot be optimized for Thumb1 if the args | // Indirect tail calls cannot be optimized for Thumb1 if the args | ||||
| // to the call take up r0-r3. The reason is that there are no legal registers | // to the call take up r0-r3. The reason is that there are no legal registers | ||||
| // left to hold the pointer to the function to be called. | // left to hold the pointer to the function to be called. | ||||
| if (Subtarget->isThumb1Only() && Outs.size() >= 4 && | // Similarly, if the function uses return address sign and authentication, | ||||
| (!isa<GlobalAddressSDNode>(Callee.getNode()) || isIndirect)) | // r12 is needed to hold the PAC and is not available to hold the callee | ||||
| // address. | |||||
| if (Outs.size() >= 4 && | |||||
| (!isa<GlobalAddressSDNode>(Callee.getNode()) || isIndirect)) { | |||||
| if (Subtarget->isThumb1Only()) | |||||
| return false; | |||||
| // Conservatively assume the function spills LR. | |||||
| if (MF.getInfo<ARMFunctionInfo>()->shouldSignReturnAddress(true)) | |||||
| return false; | return false; | ||||
| } | |||||
| // Look for obvious safe cases to perform tail call optimization that do not | // Look for obvious safe cases to perform tail call optimization that do not | ||||
| // require ABI changes. This is what gcc calls sibcall. | // require ABI changes. This is what gcc calls sibcall. | ||||
| // Exception-handling functions need a special set of instructions to indicate | // Exception-handling functions need a special set of instructions to indicate | ||||
| // a return to the hardware. Tail-calling another function would probably | // a return to the hardware. Tail-calling another function would probably | ||||
| // break this. | // break this. | ||||
| if (CallerF.hasFnAttribute("interrupt")) | if (CallerF.hasFnAttribute("interrupt")) | ||||
| ▲ Show 20 Lines • Show All 18,600 Lines • Show Last 20 Lines | |||||