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ARM: Proactively ensure that the LowerCallResult hack for 'this'-returns is not used for incompatible calling conventions.

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(Currently, ARM 'this'-returns are handled in the standard calling convention case by treating R0 as preserved and doing some extra magic in LowerCallResult; this may not apply to calling conventions added in the future so this patch provides and documents an interface for indicating such)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185024 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Stephen Lin 2013-06-26 21:42:14 +00:00
parent 02e75021d8
commit 6b97ebe9a3
3 changed files with 23 additions and 4 deletions
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3
lib/Target/ARM/ARMBaseRegisterInfo.cpp
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@ -75,6 +75,9 @@ const uint32_t*
ARMBaseRegisterInfo::getThisReturnPreservedMask(CallingConv::ID) const {
return (STI.isTargetIOS() && !STI.isAAPCS_ABI())
? CSR_iOS_ThisReturn_RegMask : CSR_AAPCS_ThisReturn_RegMask;
// This should return NULL in the case of any calling convention that does
// not use the same register for an i32 first argument and an i32 return
// value
}
const uint32_t*

11
lib/Target/ARM/ARMBaseRegisterInfo.h
View File

@ -94,9 +94,18 @@ public:
/// Code Generation virtual methods...
const uint16_t *getCalleeSavedRegs(const MachineFunction *MF = 0) const;
const uint32_t *getCallPreservedMask(CallingConv::ID) const;
const uint32_t *getThisReturnPreservedMask(CallingConv::ID) const;
const uint32_t *getNoPreservedMask() const;
// getThisReturnPreservedMask - Returns a call preserved mask specific to the
// case that 'returned' is an i32 first argument if the calling convention
// is one that can (partially) model this attribute with a preserved mask
// (i.e. it is a calling convention that uses the same register for the first
// i32 argument and an i32 return value)
//
// Should return NULL in the case that the calling convention does not have
// this property
const uint32_t *getThisReturnPreservedMask(CallingConv::ID) const;
BitVector getReservedRegs(const MachineFunction &MF) const;
const TargetRegisterClass*

13
lib/Target/ARM/ARMISelLowering.cpp
View File

@ -1711,10 +1711,17 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
const uint32_t *Mask;
const TargetRegisterInfo *TRI = getTargetMachine().getRegisterInfo();
const ARMBaseRegisterInfo *ARI = static_cast<const ARMBaseRegisterInfo*>(TRI);
if (isThisReturn)
// For 'this' returns, use the R0-preserving mask
if (isThisReturn) {
// For 'this' returns, use the R0-preserving mask if applicable
Mask = ARI->getThisReturnPreservedMask(CallConv);
else
if (!Mask) {
// Set isThisReturn to false if the calling convention is not one that
// allows 'returned' to be modeled in this way, so LowerCallResult does
// not try to pass 'this' straight through
isThisReturn = false;
Mask = ARI->getCallPreservedMask(CallConv);
}
} else
Mask = ARI->getCallPreservedMask(CallConv);
assert(Mask && "Missing call preserved mask for calling convention");