[llvm] r179925 - Add CodeGen support for functions that always return arguments via a new parameter attribute 'returned', which is taken advantage of in target-independent tail call opportunity detection and in ARM call lowering (when placed on an integral first parameter).
Stephen Lin
stephenwlin at gmail.com
Fri Apr 19 22:14:41 PDT 2013
Author: stephenwlin
Date: Sat Apr 20 00:14:40 2013
New Revision: 179925
URL: http://llvm.org/viewvc/llvm-project?rev=179925&view=rev
Log:
Add CodeGen support for functions that always return arguments via a new parameter attribute 'returned', which is taken advantage of in target-independent tail call opportunity detection and in ARM call lowering (when placed on an integral first parameter).
Added:
llvm/trunk/test/CodeGen/ARM/this-return.ll
llvm/trunk/test/CodeGen/X86/this-return-64.ll
Modified:
llvm/trunk/docs/LangRef.rst
llvm/trunk/include/llvm/IR/Argument.h
llvm/trunk/include/llvm/IR/Attributes.h
llvm/trunk/include/llvm/Target/TargetCallingConv.h
llvm/trunk/include/llvm/Target/TargetLowering.h
llvm/trunk/lib/AsmParser/LLLexer.cpp
llvm/trunk/lib/AsmParser/LLParser.cpp
llvm/trunk/lib/AsmParser/LLToken.h
llvm/trunk/lib/CodeGen/Analysis.cpp
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
llvm/trunk/lib/IR/Attributes.cpp
llvm/trunk/lib/IR/Function.cpp
llvm/trunk/lib/IR/Verifier.cpp
llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp
llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h
llvm/trunk/lib/Target/ARM/ARMCallingConv.td
llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
llvm/trunk/lib/Target/ARM/ARMISelLowering.h
Modified: llvm/trunk/docs/LangRef.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.rst?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/docs/LangRef.rst (original)
+++ llvm/trunk/docs/LangRef.rst Sat Apr 20 00:14:40 2013
@@ -719,7 +719,17 @@ Currently, only the following parameter
``nest``
This indicates that the pointer parameter can be excised using the
:ref:`trampoline intrinsics <int_trampoline>`. This is not a valid
- attribute for return values.
+ attribute for return values and can only be applied to one parameter.
+
+``returned``
+ This indicates that the value of the function always returns the value
+ of the parameter as its return value. This is an optimization hint to
+ the code generator when generating the caller, allowing tail call
+ optimization and omission of register saves and restores in some cases;
+ it is not checked or enforced when generating the callee. The parameter
+ and the function return type must be valid operands for the
+ :ref:`bitcast instruction <i_bitcast>`. This is not a valid attribute for
+ return values and can only be applied to one parameter.
.. _gc:
Modified: llvm/trunk/include/llvm/IR/Argument.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/Argument.h?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/Argument.h (original)
+++ llvm/trunk/include/llvm/IR/Argument.h Sat Apr 20 00:14:40 2013
@@ -78,6 +78,10 @@ public:
/// containing function.
bool hasStructRetAttr() const;
+ /// \brief Return true if this argument has the returned attribute on it in
+ /// its containing function.
+ bool hasReturnedAttr() const;
+
/// \brief Add a Attribute to an argument.
void addAttr(AttributeSet AS);
Modified: llvm/trunk/include/llvm/IR/Attributes.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/Attributes.h?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/Attributes.h (original)
+++ llvm/trunk/include/llvm/IR/Attributes.h Sat Apr 20 00:14:40 2013
@@ -87,6 +87,7 @@ public:
OptimizeForSize, ///< opt_size
ReadNone, ///< Function does not access memory
ReadOnly, ///< Function only reads from memory
+ Returned, ///< Return value is always equal to this argument
ReturnsTwice, ///< Function can return twice
SExt, ///< Sign extended before/after call
StackAlignment, ///< Alignment of stack for function (3 bits)
Modified: llvm/trunk/include/llvm/Target/TargetCallingConv.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetCallingConv.h?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetCallingConv.h (original)
+++ llvm/trunk/include/llvm/Target/TargetCallingConv.h Sat Apr 20 00:14:40 2013
@@ -36,10 +36,12 @@ namespace ISD {
static const uint64_t ByValOffs = 4;
static const uint64_t Nest = 1ULL<<5; ///< Nested fn static chain
static const uint64_t NestOffs = 5;
- static const uint64_t ByValAlign = 0xFULL << 6; ///< Struct alignment
- static const uint64_t ByValAlignOffs = 6;
- static const uint64_t Split = 1ULL << 10;
- static const uint64_t SplitOffs = 10;
+ static const uint64_t Returned = 1ULL<<6;
+ static const uint64_t ReturnedOffs = 6;
+ static const uint64_t ByValAlign = 0xFULL<<7; ///< Struct alignment
+ static const uint64_t ByValAlignOffs = 7;
+ static const uint64_t Split = 1ULL<<11;
+ static const uint64_t SplitOffs = 11;
static const uint64_t OrigAlign = 0x1FULL<<27;
static const uint64_t OrigAlignOffs = 27;
static const uint64_t ByValSize = 0xffffffffULL << 32; ///< Struct size
@@ -51,23 +53,26 @@ namespace ISD {
public:
ArgFlagsTy() : Flags(0) { }
- bool isZExt() const { return Flags & ZExt; }
- void setZExt() { Flags |= One << ZExtOffs; }
+ bool isZExt() const { return Flags & ZExt; }
+ void setZExt() { Flags |= One << ZExtOffs; }
- bool isSExt() const { return Flags & SExt; }
- void setSExt() { Flags |= One << SExtOffs; }
+ bool isSExt() const { return Flags & SExt; }
+ void setSExt() { Flags |= One << SExtOffs; }
- bool isInReg() const { return Flags & InReg; }
- void setInReg() { Flags |= One << InRegOffs; }
+ bool isInReg() const { return Flags & InReg; }
+ void setInReg() { Flags |= One << InRegOffs; }
- bool isSRet() const { return Flags & SRet; }
- void setSRet() { Flags |= One << SRetOffs; }
+ bool isSRet() const { return Flags & SRet; }
+ void setSRet() { Flags |= One << SRetOffs; }
- bool isByVal() const { return Flags & ByVal; }
- void setByVal() { Flags |= One << ByValOffs; }
+ bool isByVal() const { return Flags & ByVal; }
+ void setByVal() { Flags |= One << ByValOffs; }
- bool isNest() const { return Flags & Nest; }
- void setNest() { Flags |= One << NestOffs; }
+ bool isNest() const { return Flags & Nest; }
+ void setNest() { Flags |= One << NestOffs; }
+
+ bool isReturned() const { return Flags & Returned; }
+ void setReturned() { Flags |= One << ReturnedOffs; }
unsigned getByValAlign() const {
return (unsigned)
Modified: llvm/trunk/include/llvm/Target/TargetLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetLowering.h?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetLowering.h (original)
+++ llvm/trunk/include/llvm/Target/TargetLowering.h Sat Apr 20 00:14:40 2013
@@ -1910,16 +1910,18 @@ public:
struct ArgListEntry {
SDValue Node;
Type* Ty;
- bool isSExt : 1;
- bool isZExt : 1;
- bool isInReg : 1;
- bool isSRet : 1;
- bool isNest : 1;
- bool isByVal : 1;
+ bool isSExt : 1;
+ bool isZExt : 1;
+ bool isInReg : 1;
+ bool isSRet : 1;
+ bool isNest : 1;
+ bool isByVal : 1;
+ bool isReturned : 1;
uint16_t Alignment;
ArgListEntry() : isSExt(false), isZExt(false), isInReg(false),
- isSRet(false), isNest(false), isByVal(false), Alignment(0) { }
+ isSRet(false), isNest(false), isByVal(false), isReturned(false),
+ Alignment(0) { }
};
typedef std::vector<ArgListEntry> ArgListTy;
Modified: llvm/trunk/lib/AsmParser/LLLexer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/AsmParser/LLLexer.cpp?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/AsmParser/LLLexer.cpp (original)
+++ llvm/trunk/lib/AsmParser/LLLexer.cpp Sat Apr 20 00:14:40 2013
@@ -582,6 +582,7 @@ lltok::Kind LLLexer::LexIdentifier() {
KEYWORD(optsize);
KEYWORD(readnone);
KEYWORD(readonly);
+ KEYWORD(returned);
KEYWORD(returns_twice);
KEYWORD(signext);
KEYWORD(sret);
Modified: llvm/trunk/lib/AsmParser/LLParser.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/AsmParser/LLParser.cpp?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/AsmParser/LLParser.cpp (original)
+++ llvm/trunk/lib/AsmParser/LLParser.cpp Sat Apr 20 00:14:40 2013
@@ -944,6 +944,7 @@ bool LLParser::ParseFnAttributeValuePair
case lltok::kw_nest:
case lltok::kw_noalias:
case lltok::kw_nocapture:
+ case lltok::kw_returned:
case lltok::kw_sret:
HaveError |=
Error(Lex.getLoc(),
@@ -1156,6 +1157,7 @@ bool LLParser::ParseOptionalParamAttrs(A
case lltok::kw_nest: B.addAttribute(Attribute::Nest); break;
case lltok::kw_noalias: B.addAttribute(Attribute::NoAlias); break;
case lltok::kw_nocapture: B.addAttribute(Attribute::NoCapture); break;
+ case lltok::kw_returned: B.addAttribute(Attribute::Returned); break;
case lltok::kw_signext: B.addAttribute(Attribute::SExt); break;
case lltok::kw_sret: B.addAttribute(Attribute::StructRet); break;
case lltok::kw_zeroext: B.addAttribute(Attribute::ZExt); break;
@@ -1199,6 +1201,7 @@ bool LLParser::ParseOptionalReturnAttrs(
case lltok::kw_byval:
case lltok::kw_nest:
case lltok::kw_nocapture:
+ case lltok::kw_returned:
case lltok::kw_sret:
HaveError |= Error(Lex.getLoc(), "invalid use of parameter-only attribute");
break;
Modified: llvm/trunk/lib/AsmParser/LLToken.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/AsmParser/LLToken.h?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/AsmParser/LLToken.h (original)
+++ llvm/trunk/lib/AsmParser/LLToken.h Sat Apr 20 00:14:40 2013
@@ -114,6 +114,7 @@ namespace lltok {
kw_optsize,
kw_readnone,
kw_readonly,
+ kw_returned,
kw_returns_twice,
kw_signext,
kw_ssp,
Modified: llvm/trunk/lib/CodeGen/Analysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/Analysis.cpp?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/Analysis.cpp (original)
+++ llvm/trunk/lib/CodeGen/Analysis.cpp Sat Apr 20 00:14:40 2013
@@ -261,6 +261,32 @@ static bool sameNoopInput(const Value *V
TLI.getPointerTy().getSizeInBits() ==
cast<IntegerType>(I->getType())->getBitWidth())
NoopInput = Op;
+ } else if (isa<CallInst>(I)) {
+ // Look through call
+ for (User::const_op_iterator i = I->op_begin(),
+ // Skip Callee
+ e = I->op_end() - 1;
+ i != e; ++i) {
+ unsigned attrInd = i - I->op_begin() + 1;
+ if (cast<CallInst>(I)->paramHasAttr(attrInd, Attribute::Returned) &&
+ isNoopBitcast((*i)->getType(), I->getType(), TLI)) {
+ NoopInput = *i;
+ break;
+ }
+ }
+ } else if (isa<InvokeInst>(I)) {
+ // Look through invoke
+ for (User::const_op_iterator i = I->op_begin(),
+ // Skip BB, BB, Callee
+ e = I->op_end() - 3;
+ i != e; ++i) {
+ unsigned attrInd = i - I->op_begin() + 1;
+ if (cast<InvokeInst>(I)->paramHasAttr(attrInd, Attribute::Returned) &&
+ isNoopBitcast((*i)->getType(), I->getType(), TLI)) {
+ NoopInput = *i;
+ break;
+ }
+ }
}
}
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Sat Apr 20 00:14:40 2013
@@ -5232,6 +5232,7 @@ void SelectionDAGBuilder::LowerCallTo(Im
Entry.isSRet = true;
Entry.isNest = false;
Entry.isByVal = false;
+ Entry.isReturned = false;
Entry.Alignment = Align;
Args.push_back(Entry);
RetTy = Type::getVoidTy(FTy->getContext());
@@ -5249,13 +5250,14 @@ void SelectionDAGBuilder::LowerCallTo(Im
Entry.Node = ArgNode; Entry.Ty = V->getType();
unsigned attrInd = i - CS.arg_begin() + 1;
- Entry.isSExt = CS.paramHasAttr(attrInd, Attribute::SExt);
- Entry.isZExt = CS.paramHasAttr(attrInd, Attribute::ZExt);
- Entry.isInReg = CS.paramHasAttr(attrInd, Attribute::InReg);
- Entry.isSRet = CS.paramHasAttr(attrInd, Attribute::StructRet);
- Entry.isNest = CS.paramHasAttr(attrInd, Attribute::Nest);
- Entry.isByVal = CS.paramHasAttr(attrInd, Attribute::ByVal);
- Entry.Alignment = CS.getParamAlignment(attrInd);
+ Entry.isSExt = CS.paramHasAttr(attrInd, Attribute::SExt);
+ Entry.isZExt = CS.paramHasAttr(attrInd, Attribute::ZExt);
+ Entry.isInReg = CS.paramHasAttr(attrInd, Attribute::InReg);
+ Entry.isSRet = CS.paramHasAttr(attrInd, Attribute::StructRet);
+ Entry.isNest = CS.paramHasAttr(attrInd, Attribute::Nest);
+ Entry.isByVal = CS.paramHasAttr(attrInd, Attribute::ByVal);
+ Entry.isReturned = CS.paramHasAttr(attrInd, Attribute::Returned);
+ Entry.Alignment = CS.getParamAlignment(attrInd);
Args.push_back(Entry);
}
@@ -6430,6 +6432,8 @@ TargetLowering::LowerCallTo(TargetLoweri
}
if (Args[i].isNest)
Flags.setNest();
+ if (Args[i].isReturned)
+ Flags.setReturned();
Flags.setOrigAlign(OriginalAlignment);
MVT PartVT = getRegisterType(CLI.RetTy->getContext(), VT);
Modified: llvm/trunk/lib/IR/Attributes.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Attributes.cpp?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Attributes.cpp (original)
+++ llvm/trunk/lib/IR/Attributes.cpp Sat Apr 20 00:14:40 2013
@@ -195,6 +195,8 @@ std::string Attribute::getAsString(bool
return "readnone";
if (hasAttribute(Attribute::ReadOnly))
return "readonly";
+ if (hasAttribute(Attribute::Returned))
+ return "returned";
if (hasAttribute(Attribute::ReturnsTwice))
return "returns_twice";
if (hasAttribute(Attribute::SExt))
@@ -393,6 +395,7 @@ uint64_t AttributeImpl::getAttrMask(Attr
case Attribute::SanitizeThread: return 1ULL << 36;
case Attribute::SanitizeMemory: return 1ULL << 37;
case Attribute::NoBuiltin: return 1ULL << 38;
+ case Attribute::Returned: return 1ULL << 39;
}
llvm_unreachable("Unsupported attribute type");
}
Modified: llvm/trunk/lib/IR/Function.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Function.cpp?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Function.cpp (original)
+++ llvm/trunk/lib/IR/Function.cpp Sat Apr 20 00:14:40 2013
@@ -124,6 +124,13 @@ bool Argument::hasStructRetAttr() const
hasAttribute(1, Attribute::StructRet);
}
+/// hasReturnedAttr - Return true if this argument has the returned attribute on
+/// it in its containing function.
+bool Argument::hasReturnedAttr() const {
+ return getParent()->getAttributes().
+ hasAttribute(getArgNo()+1, Attribute::Returned);
+}
+
/// addAttr - Add attributes to an argument.
void Argument::addAttr(AttributeSet AS) {
assert(AS.getNumSlots() <= 1 &&
Modified: llvm/trunk/lib/IR/Verifier.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Verifier.cpp?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Verifier.cpp (original)
+++ llvm/trunk/lib/IR/Verifier.cpp Sat Apr 20 00:14:40 2013
@@ -694,8 +694,9 @@ void Verifier::VerifyParameterAttrs(Attr
Assert1(!Attrs.hasAttribute(Idx, Attribute::ByVal) &&
!Attrs.hasAttribute(Idx, Attribute::Nest) &&
!Attrs.hasAttribute(Idx, Attribute::StructRet) &&
- !Attrs.hasAttribute(Idx, Attribute::NoCapture),
- "Attribute 'byval', 'nest', 'sret', and 'nocapture' "
+ !Attrs.hasAttribute(Idx, Attribute::NoCapture) &&
+ !Attrs.hasAttribute(Idx, Attribute::Returned),
+ "Attribute 'byval', 'nest', 'sret', 'nocapture', and 'returned' "
"do not apply to return values!", V);
// Check for mutually incompatible attributes.
@@ -750,6 +751,7 @@ void Verifier::VerifyFunctionAttrs(Funct
return;
bool SawNest = false;
+ bool SawReturned = false;
for (unsigned i = 0, e = Attrs.getNumSlots(); i != e; ++i) {
unsigned Idx = Attrs.getSlotIndex(i);
@@ -764,11 +766,22 @@ void Verifier::VerifyFunctionAttrs(Funct
VerifyParameterAttrs(Attrs, Idx, Ty, Idx == 0, V);
- if (Attrs.hasAttribute(i, Attribute::Nest)) {
+ if (Idx == 0)
+ continue;
+
+ if (Attrs.hasAttribute(Idx, Attribute::Nest)) {
Assert1(!SawNest, "More than one parameter has attribute nest!", V);
SawNest = true;
}
+ if (Attrs.hasAttribute(Idx, Attribute::Returned)) {
+ Assert1(!SawReturned, "More than one parameter has attribute returned!",
+ V);
+ Assert1(Ty->canLosslesslyBitCastTo(FT->getReturnType()), "Incompatible "
+ "argument and return types for 'returned' attribute", V);
+ SawReturned = true;
+ }
+
if (Attrs.hasAttribute(Idx, Attribute::StructRet))
Assert1(Idx == 1, "Attribute sret is not on first parameter!", V);
}
@@ -1348,15 +1361,41 @@ void Verifier::VerifyCallSite(CallSite C
// Verify call attributes.
VerifyFunctionAttrs(FTy, Attrs, I);
- if (FTy->isVarArg())
+ if (FTy->isVarArg()) {
+ // FIXME? is 'nest' even legal here?
+ bool SawNest = false;
+ bool SawReturned = false;
+
+ for (unsigned Idx = 1; Idx < 1 + FTy->getNumParams(); ++Idx) {
+ if (Attrs.hasAttribute(Idx, Attribute::Nest))
+ SawNest = true;
+ if (Attrs.hasAttribute(Idx, Attribute::Returned))
+ SawReturned = true;
+ }
+
// Check attributes on the varargs part.
for (unsigned Idx = 1 + FTy->getNumParams(); Idx <= CS.arg_size(); ++Idx) {
- VerifyParameterAttrs(Attrs, Idx, CS.getArgument(Idx-1)->getType(),
- false, I);
+ Type *Ty = CS.getArgument(Idx-1)->getType();
+ VerifyParameterAttrs(Attrs, Idx, Ty, false, I);
+
+ if (Attrs.hasAttribute(Idx, Attribute::Nest)) {
+ Assert1(!SawNest, "More than one parameter has attribute nest!", I);
+ SawNest = true;
+ }
+
+ if (Attrs.hasAttribute(Idx, Attribute::Returned)) {
+ Assert1(!SawReturned, "More than one parameter has attribute returned!",
+ I);
+ Assert1(Ty->canLosslesslyBitCastTo(FTy->getReturnType()),
+ "Incompatible argument and return types for 'returned' "
+ "attribute", I);
+ SawReturned = true;
+ }
Assert1(!Attrs.hasAttribute(Idx, Attribute::StructRet),
"Attribute 'sret' cannot be used for vararg call arguments!", I);
}
+ }
// Verify that there's no metadata unless it's a direct call to an intrinsic.
if (CS.getCalledFunction() == 0 ||
Modified: llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.cpp Sat Apr 20 00:14:40 2013
@@ -75,6 +75,12 @@ ARMBaseRegisterInfo::getCallPreservedMas
}
const uint32_t*
+ARMBaseRegisterInfo::getThisReturnPreservedMask(CallingConv::ID) const {
+ return (STI.isTargetIOS() && !STI.isAAPCS_ABI())
+ ? CSR_iOS_ThisReturn_RegMask : CSR_AAPCS_ThisReturn_RegMask;
+}
+
+const uint32_t*
ARMBaseRegisterInfo::getNoPreservedMask() const {
return CSR_NoRegs_RegMask;
}
Modified: llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h (original)
+++ llvm/trunk/lib/Target/ARM/ARMBaseRegisterInfo.h Sat Apr 20 00:14:40 2013
@@ -96,6 +96,7 @@ 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;
BitVector getReservedRegs(const MachineFunction &MF) const;
Modified: llvm/trunk/lib/Target/ARM/ARMCallingConv.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMCallingConv.td?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMCallingConv.td (original)
+++ llvm/trunk/lib/Target/ARM/ARMCallingConv.td Sat Apr 20 00:14:40 2013
@@ -195,10 +195,21 @@ def CSR_NoRegs : CalleeSavedRegs<(add)>;
def CSR_AAPCS : CalleeSavedRegs<(add LR, R11, R10, R9, R8, R7, R6, R5, R4,
(sequence "D%u", 15, 8))>;
+// Constructors and destructors return 'this' in the ARM C++ ABI; since 'this'
+// and the pointer return value are both passed in R0 in these cases, this can
+// be partially modelled by treating R0 as a callee-saved register
+// Only the resulting RegMask is used; the SaveList is ignored
+def CSR_AAPCS_ThisReturn : CalleeSavedRegs<(add LR, R11, R10, R9, R8, R7, R6,
+ R5, R4, (sequence "D%u", 15, 8),
+ R0)>;
+
// iOS ABI deviates from ARM standard ABI. R9 is not a callee-saved register.
// Also save R7-R4 first to match the stack frame fixed spill areas.
def CSR_iOS : CalleeSavedRegs<(add LR, R7, R6, R5, R4, (sub CSR_AAPCS, R9))>;
+def CSR_iOS_ThisReturn : CalleeSavedRegs<(add LR, R7, R6, R5, R4,
+ (sub CSR_AAPCS_ThisReturn, R9))>;
+
// GHC set of callee saved regs is empty as all those regs are
// used for passing STG regs around
// add is a workaround for not being able to compile empty list:
Modified: llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp Sat Apr 20 00:14:40 2013
@@ -1238,7 +1238,8 @@ ARMTargetLowering::LowerCallResult(SDVal
CallingConv::ID CallConv, bool isVarArg,
const SmallVectorImpl<ISD::InputArg> &Ins,
DebugLoc dl, SelectionDAG &DAG,
- SmallVectorImpl<SDValue> &InVals) const {
+ SmallVectorImpl<SDValue> &InVals,
+ bool isThisReturn, SDValue ThisVal) const {
// Assign locations to each value returned by this call.
SmallVector<CCValAssign, 16> RVLocs;
@@ -1252,6 +1253,14 @@ ARMTargetLowering::LowerCallResult(SDVal
for (unsigned i = 0; i != RVLocs.size(); ++i) {
CCValAssign VA = RVLocs[i];
+ // Pass 'this' value directly from the argument to return value, to avoid
+ // reg unit interference
+ if (i == 0 && isThisReturn) {
+ assert(!VA.needsCustom() && VA.getLocVT() == MVT::i32);
+ InVals.push_back(ThisVal);
+ continue;
+ }
+
SDValue Val;
if (VA.needsCustom()) {
// Handle f64 or half of a v2f64.
@@ -1364,7 +1373,8 @@ ARMTargetLowering::LowerCall(TargetLower
MachineFunction &MF = DAG.getMachineFunction();
bool IsStructRet = (Outs.empty()) ? false : Outs[0].Flags.isSRet();
- bool IsSibCall = false;
+ bool IsThisReturn = false;
+ bool IsSibCall = false;
// Disable tail calls if they're not supported.
if (!EnableARMTailCalls && !Subtarget->supportsTailCall())
isTailCall = false;
@@ -1460,6 +1470,11 @@ ARMTargetLowering::LowerCall(TargetLower
StackPtr, MemOpChains, Flags);
}
} else if (VA.isRegLoc()) {
+ if (realArgIdx == 0 && Flags.isReturned() && VA.getLocVT() == MVT::i32) {
+ assert(!Ins.empty() && Ins[0].VT == Outs[0].VT &&
+ "unexpected use of 'returned'");
+ IsThisReturn = true;
+ }
RegsToPass.push_back(std::make_pair(VA.getLocReg(), Arg));
} else if (isByVal) {
assert(VA.isMemLoc());
@@ -1680,8 +1695,15 @@ ARMTargetLowering::LowerCall(TargetLower
RegsToPass[i].second.getValueType()));
// Add a register mask operand representing the call-preserved registers.
+ const uint32_t *Mask;
const TargetRegisterInfo *TRI = getTargetMachine().getRegisterInfo();
- const uint32_t *Mask = TRI->getCallPreservedMask(CallConv);
+ const ARMBaseRegisterInfo *ARI = static_cast<const ARMBaseRegisterInfo*>(TRI);
+ if (IsThisReturn)
+ // For 'this' returns, use the R0-preserving mask
+ Mask = ARI->getThisReturnPreservedMask(CallConv);
+ else
+ Mask = ARI->getCallPreservedMask(CallConv);
+
assert(Mask && "Missing call preserved mask for calling convention");
Ops.push_back(DAG.getRegisterMask(Mask));
@@ -1703,8 +1725,9 @@ ARMTargetLowering::LowerCall(TargetLower
// Handle result values, copying them out of physregs into vregs that we
// return.
- return LowerCallResult(Chain, InFlag, CallConv, isVarArg, Ins,
- dl, DAG, InVals);
+ return LowerCallResult(Chain, InFlag, CallConv, isVarArg, Ins, dl, DAG,
+ InVals, IsThisReturn,
+ IsThisReturn ? OutVals[0] : SDValue());
}
/// HandleByVal - Every parameter *after* a byval parameter is passed
Modified: llvm/trunk/lib/Target/ARM/ARMISelLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMISelLowering.h?rev=179925&r1=179924&r2=179925&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMISelLowering.h (original)
+++ llvm/trunk/lib/Target/ARM/ARMISelLowering.h Sat Apr 20 00:14:40 2013
@@ -464,7 +464,8 @@ namespace llvm {
CallingConv::ID CallConv, bool isVarArg,
const SmallVectorImpl<ISD::InputArg> &Ins,
DebugLoc dl, SelectionDAG &DAG,
- SmallVectorImpl<SDValue> &InVals) const;
+ SmallVectorImpl<SDValue> &InVals,
+ bool isThisReturn, SDValue ThisVal) const;
virtual SDValue
LowerFormalArguments(SDValue Chain,
Added: llvm/trunk/test/CodeGen/ARM/this-return.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/this-return.ll?rev=179925&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/this-return.ll (added)
+++ llvm/trunk/test/CodeGen/ARM/this-return.ll Sat Apr 20 00:14:40 2013
@@ -0,0 +1,91 @@
+; RUN: llc < %s -mtriple=armv6-linux-gnueabi -arm-tail-calls | FileCheck %s -check-prefix=CHECKELF
+; RUN: llc < %s -mtriple=thumbv7-apple-ios -arm-tail-calls | FileCheck %s -check-prefix=CHECKT2D
+
+%struct.A = type { i8 }
+%struct.B = type { i32 }
+%struct.C = type { %struct.B }
+%struct.D = type { %struct.B }
+
+declare %struct.A* @A_ctor_base(%struct.A* returned)
+declare %struct.B* @B_ctor_base(%struct.B* returned, i32)
+declare %struct.B* @B_ctor_complete(%struct.B* returned, i32)
+
+declare %struct.A* @A_ctor_base_nothisret(%struct.A*)
+declare %struct.B* @B_ctor_base_nothisret(%struct.B*, i32)
+declare %struct.B* @B_ctor_complete_nothisret(%struct.B*, i32)
+
+define %struct.C* @C_ctor_base(%struct.C* returned %this, i32 %x) {
+entry:
+; CHECKELF: C_ctor_base:
+; CHECKELF-NOT: mov {{r[0-9]+}}, r0
+; CHECKELF: bl A_ctor_base
+; CHECKELF-NOT: mov r0, {{r[0-9]+}}
+; CHECKELF: b B_ctor_base
+; CHECKT2D: C_ctor_base:
+; CHECKT2D-NOT: mov {{r[0-9]+}}, r0
+; CHECKT2D: blx _A_ctor_base
+; CHECKT2D-NOT: mov r0, {{r[0-9]+}}
+; CHECKT2D: b.w _B_ctor_base
+ %0 = bitcast %struct.C* %this to %struct.A*
+ %call = tail call %struct.A* @A_ctor_base(%struct.A* %0)
+ %1 = getelementptr inbounds %struct.C* %this, i32 0, i32 0
+ %call2 = tail call %struct.B* @B_ctor_base(%struct.B* %1, i32 %x)
+ ret %struct.C* %this
+}
+
+define %struct.C* @C_ctor_base_nothisret(%struct.C* %this, i32 %x) {
+entry:
+; CHECKELF: C_ctor_base_nothisret:
+; CHECKELF: mov [[SAVETHIS:r[0-9]+]], r0
+; CHECKELF: bl A_ctor_base_nothisret
+; CHECKELF: mov r0, [[SAVETHIS]]
+; CHECKELF-NOT: b B_ctor_base_nothisret
+; CHECKT2D: C_ctor_base_nothisret:
+; CHECKT2D: mov [[SAVETHIS:r[0-9]+]], r0
+; CHECKT2D: blx _A_ctor_base_nothisret
+; CHECKT2D: mov r0, [[SAVETHIS]]
+; CHECKT2D-NOT: b.w _B_ctor_base_nothisret
+ %0 = bitcast %struct.C* %this to %struct.A*
+ %call = tail call %struct.A* @A_ctor_base_nothisret(%struct.A* %0)
+ %1 = getelementptr inbounds %struct.C* %this, i32 0, i32 0
+ %call2 = tail call %struct.B* @B_ctor_base_nothisret(%struct.B* %1, i32 %x)
+ ret %struct.C* %this
+}
+
+define %struct.C* @C_ctor_complete(%struct.C* %this, i32 %x) {
+entry:
+; CHECKELF: C_ctor_complete:
+; CHECKELF: b C_ctor_base
+; CHECKT2D: C_ctor_complete:
+; CHECKT2D: b.w _C_ctor_base
+ %call = tail call %struct.C* @C_ctor_base(%struct.C* %this, i32 %x)
+ ret %struct.C* %this
+}
+
+define %struct.C* @C_ctor_complete_nothisret(%struct.C* %this, i32 %x) {
+entry:
+; CHECKELF: C_ctor_complete_nothisret:
+; CHECKELF-NOT: b C_ctor_base_nothisret
+; CHECKT2D: C_ctor_complete_nothisret:
+; CHECKT2D-NOT: b.w _C_ctor_base_nothisret
+ %call = tail call %struct.C* @C_ctor_base_nothisret(%struct.C* %this, i32 %x)
+ ret %struct.C* %this
+}
+
+define %struct.D* @D_ctor_base(%struct.D* %this, i32 %x) {
+entry:
+; CHECKELF: D_ctor_base:
+; CHECKELF-NOT: mov {{r[0-9]+}}, r0
+; CHECKELF: bl B_ctor_complete
+; CHECKELF-NOT: mov r0, {{r[0-9]+}}
+; CHECKELF: b B_ctor_complete
+; CHECKT2D: D_ctor_base:
+; CHECKT2D-NOT: mov {{r[0-9]+}}, r0
+; CHECKT2D: blx _B_ctor_complete
+; CHECKT2D-NOT: mov r0, {{r[0-9]+}}
+; CHECKT2D: b.w _B_ctor_complete
+ %b = getelementptr inbounds %struct.D* %this, i32 0, i32 0
+ %call = tail call %struct.B* @B_ctor_complete(%struct.B* %b, i32 %x)
+ %call2 = tail call %struct.B* @B_ctor_complete(%struct.B* %b, i32 %x)
+ ret %struct.D* %this
+}
Added: llvm/trunk/test/CodeGen/X86/this-return-64.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/this-return-64.ll?rev=179925&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/this-return-64.ll (added)
+++ llvm/trunk/test/CodeGen/X86/this-return-64.ll Sat Apr 20 00:14:40 2013
@@ -0,0 +1,89 @@
+; RUN: llc < %s -mtriple=x86_64-pc-win32 | FileCheck %s
+
+%struct.A = type { i8 }
+%struct.B = type { i32 }
+%struct.C = type { %struct.B }
+%struct.D = type { %struct.B }
+%struct.E = type { %struct.B }
+
+declare %struct.A* @A_ctor(%struct.A* returned)
+declare %struct.B* @B_ctor(%struct.B* returned, i32)
+
+declare %struct.A* @A_ctor_nothisret(%struct.A*)
+declare %struct.B* @B_ctor_nothisret(%struct.B*, i32)
+
+define %struct.C* @C_ctor(%struct.C* %this, i32 %y) {
+entry:
+; CHECK: C_ctor:
+; CHECK: jmp B_ctor # TAILCALL
+ %0 = getelementptr inbounds %struct.C* %this, i64 0, i32 0
+ %call = tail call %struct.B* @B_ctor(%struct.B* %0, i32 %y)
+ ret %struct.C* %this
+}
+
+define %struct.C* @C_ctor_nothisret(%struct.C* %this, i32 %y) {
+entry:
+; CHECK: C_ctor_nothisret:
+; CHECK-NOT: jmp B_ctor_nothisret
+ %0 = getelementptr inbounds %struct.C* %this, i64 0, i32 0
+ %call = tail call %struct.B* @B_ctor_nothisret(%struct.B* %0, i32 %y)
+ ret %struct.C* %this
+}
+
+define %struct.D* @D_ctor(%struct.D* %this, i32 %y) {
+entry:
+; CHECK: D_ctor:
+; CHECK: movq %rcx, [[SAVETHIS:%r[0-9a-z]+]]
+; CHECK: callq A_ctor
+; CHECK: movq [[SAVETHIS]], %rcx
+; CHECK: jmp B_ctor # TAILCALL
+ %0 = bitcast %struct.D* %this to %struct.A*
+ %call = tail call %struct.A* @A_ctor(%struct.A* %0)
+ %1 = getelementptr inbounds %struct.D* %this, i64 0, i32 0
+ %call2 = tail call %struct.B* @B_ctor(%struct.B* %1, i32 %y)
+; (this next line would never be generated by Clang, actually)
+ %2 = bitcast %struct.A* %call to %struct.D*
+ ret %struct.D* %2
+}
+
+define %struct.D* @D_ctor_nothisret(%struct.D* %this, i32 %y) {
+entry:
+; CHECK: D_ctor_nothisret:
+; CHECK: movq %rcx, [[SAVETHIS:%r[0-9a-z]+]]
+; CHECK: callq A_ctor_nothisret
+; CHECK: movq [[SAVETHIS]], %rcx
+; CHECK-NOT: jmp B_ctor_nothisret
+ %0 = bitcast %struct.D* %this to %struct.A*
+ %call = tail call %struct.A* @A_ctor_nothisret(%struct.A* %0)
+ %1 = getelementptr inbounds %struct.D* %this, i64 0, i32 0
+ %call2 = tail call %struct.B* @B_ctor_nothisret(%struct.B* %1, i32 %y)
+; (this next line would never be generated by Clang, actually)
+ %2 = bitcast %struct.A* %call to %struct.D*
+ ret %struct.D* %2
+}
+
+define %struct.E* @E_ctor(%struct.E* %this, i32 %x) {
+entry:
+; CHECK: E_ctor:
+; CHECK: movq %rcx, [[SAVETHIS:%r[0-9a-z]+]]
+; CHECK: callq B_ctor
+; CHECK: movq [[SAVETHIS]], %rcx
+; CHECK: jmp B_ctor # TAILCALL
+ %b = getelementptr inbounds %struct.E* %this, i64 0, i32 0
+ %call = tail call %struct.B* @B_ctor(%struct.B* %b, i32 %x)
+ %call4 = tail call %struct.B* @B_ctor(%struct.B* %b, i32 %x)
+ ret %struct.E* %this
+}
+
+define %struct.E* @E_ctor_nothisret(%struct.E* %this, i32 %x) {
+entry:
+; CHECK: E_ctor_nothisret:
+; CHECK: movq %rcx, [[SAVETHIS:%r[0-9a-z]+]]
+; CHECK: callq B_ctor_nothisret
+; CHECK: movq [[SAVETHIS]], %rcx
+; CHECK-NOT: jmp B_ctor_nothisret
+ %b = getelementptr inbounds %struct.E* %this, i64 0, i32 0
+ %call = tail call %struct.B* @B_ctor_nothisret(%struct.B* %b, i32 %x)
+ %call4 = tail call %struct.B* @B_ctor_nothisret(%struct.B* %b, i32 %x)
+ ret %struct.E* %this
+}
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