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[AMDGPU] Lower null pointers in static variable initializer

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For amdgcn target Clang generates addrspacecast to represent null pointers in private and local address spaces.

    In LLVM codegen, the static variable initializer is lowered by virtual function AsmPrinter::lowerConstant which is target generic. Since addrspacecast is target specific, AsmPrinter::lowerConst

    This patch overrides AsmPrinter::lowerConstant with AMDGPUAsmPrinter::lowerConstant, which is able to lower the target-specific addrspacecast in the null pointer representation so that -1 is co

    Differential Revision: https://reviews.llvm.org/D29284

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294265 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Yaxun Liu 2017-02-07 00:43:21 +00:00
parent 85df5176ce
commit d14a49a05f
4 changed files with 152 additions and 0 deletions
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5
lib/Target/AMDGPU/AMDGPUAsmPrinter.h
View File

@ -111,6 +111,11 @@ public:
/// pseudo lowering.
bool lowerOperand(const MachineOperand &MO, MCOperand &MCOp) const;
/// \brief Lower the specified LLVM Constant to an MCExpr.
/// The AsmPrinter::lowerConstantof does not know how to lower
/// addrspacecast, therefore they should be lowered by this function.
const MCExpr *lowerConstant(const Constant *CV) override;
/// \brief tblgen'erated driver function for lowering simple MI->MC pseudo
/// instructions.
bool emitPseudoExpansionLowering(MCStreamer &OutStreamer,

22
lib/Target/AMDGPU/AMDGPUMCInstLower.cpp
View File

@ -151,6 +151,28 @@ bool AMDGPUAsmPrinter::lowerOperand(const MachineOperand &MO,
return MCInstLowering.lowerOperand(MO, MCOp);
}
const MCExpr *AMDGPUAsmPrinter::lowerConstant(const Constant *CV) {
// TargetMachine does not support llvm-style cast. Use C++-style cast.
// This is safe since TM is always of type AMDGPUTargetMachine or its
// derived class.
auto *AT = static_cast<AMDGPUTargetMachine*>(&TM);
auto *CE = dyn_cast<ConstantExpr>(CV);
// Lower null pointers in private and local address space.
// Clang generates addrspacecast for null pointers in private and local
// address space, which needs to be lowered.
if (CE && CE->getOpcode() == Instruction::AddrSpaceCast) {
auto Op = CE->getOperand(0);
auto SrcAddr = Op->getType()->getPointerAddressSpace();
if (Op->isNullValue() && AT->getNullPointerValue(SrcAddr) == 0) {
auto DstAddr = CE->getType()->getPointerAddressSpace();
return MCConstantExpr::create(AT->getNullPointerValue(DstAddr),
OutContext);
}
}
return AsmPrinter::lowerConstant(CV);
}
void AMDGPUAsmPrinter::EmitInstruction(const MachineInstr *MI) {
if (emitPseudoExpansionLowering(*OutStreamer, MI))
return;

12
lib/Target/AMDGPU/AMDGPUTargetMachine.h
View File

@ -59,6 +59,18 @@ public:
}
void adjustPassManager(PassManagerBuilder &) override;
/// Get the integer value of a null pointer in the given address space.
uint64_t getNullPointerValue(unsigned AddrSpace) const {
switch(AddrSpace) {
case AMDGPUAS::PRIVATE_ADDRESS:
case AMDGPUAS::LOCAL_ADDRESS:
case AMDGPUAS::REGION_ADDRESS:
return -1;
default:
return 0;
}
}
};
//===----------------------------------------------------------------------===//

113
test/CodeGen/AMDGPU/nullptr.ll Normal file
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@ -0,0 +1,113 @@
;RUN: llc < %s -march=amdgcn -verify-machineinstrs | FileCheck %s
%struct.S = type { i32*, i32 addrspace(1)*, i32 addrspace(2)*, i32 addrspace(3)*, i32 addrspace(4)*, i32 addrspace(5)*}
; CHECK-LABEL: nullptr_priv:
; CHECK-NEXT: .long -1
@nullptr_priv = global i32* addrspacecast (i32 addrspace(4)* null to i32*)
; CHECK-LABEL: nullptr_glob:
; CHECK-NEXT: .quad 0
@nullptr_glob = global i32 addrspace(1)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(1)*)
; CHECK-LABEL: nullptr_const:
; CHECK-NEXT: .quad 0
@nullptr_const = global i32 addrspace(2)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(2)*)
; CHECK-LABEL: nullptr_local:
; CHECK-NEXT: .long -1
@nullptr_local = global i32 addrspace(3)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(3)*)
; CHECK-LABEL: nullptr_region:
; CHECK-NEXT: .long -1
@nullptr_region = global i32 addrspace(5)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(5)*)
; CHECK-LABEL: nullptr6:
; CHECK-NEXT: .long 0
@nullptr6 = global i32 addrspace(6)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(6)*)
; CHECK-LABEL: nullptr7:
; CHECK-NEXT: .long 0
@nullptr7 = global i32 addrspace(7)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(7)*)
; CHECK-LABEL: nullptr8:
; CHECK-NEXT: .long 0
@nullptr8 = global i32 addrspace(8)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(8)*)
; CHECK-LABEL: nullptr9:
; CHECK-NEXT: .long 0
@nullptr9 = global i32 addrspace(9)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(9)*)
; CHECK-LABEL: nullptr10:
; CHECK-NEXT: .long 0
@nullptr10 = global i32 addrspace(10)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(10)*)
; CHECK-LABEL: nullptr11:
; CHECK-NEXT: .long 0
@nullptr11 = global i32 addrspace(11)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(11)*)
; CHECK-LABEL: nullptr12:
; CHECK-NEXT: .long 0
@nullptr12 = global i32 addrspace(12)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(12)*)
; CHECK-LABEL: nullptr13:
; CHECK-NEXT: .long 0
@nullptr13 = global i32 addrspace(13)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(13)*)
; CHECK-LABEL: nullptr14:
; CHECK-NEXT: .long 0
@nullptr14 = global i32 addrspace(14)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(14)*)
; CHECK-LABEL: nullptr15:
; CHECK-NEXT: .long 0
@nullptr15 = global i32 addrspace(15)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(15)*)
; CHECK-LABEL: nullptr16:
; CHECK-NEXT: .long 0
@nullptr16 = global i32 addrspace(16)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(16)*)
; CHECK-LABEL: nullptr17:
; CHECK-NEXT: .long 0
@nullptr17 = global i32 addrspace(17)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(17)*)
; CHECK-LABEL: nullptr18:
; CHECK-NEXT: .long 0
@nullptr18 = global i32 addrspace(18)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(18)*)
; CHECK-LABEL: nullptr19:
; CHECK-NEXT: .long 0
@nullptr19 = global i32 addrspace(19)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(19)*)
; CHECK-LABEL: nullptr20:
; CHECK-NEXT: .long 0
@nullptr20 = global i32 addrspace(20)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(20)*)
; CHECK-LABEL: nullptr21:
; CHECK-NEXT: .long 0
@nullptr21 = global i32 addrspace(21)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(21)*)
; CHECK-LABEL: nullptr22:
; CHECK-NEXT: .long 0
@nullptr22 = global i32 addrspace(22)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(22)*)
; CHECK-LABEL: nullptr23:
; CHECK-NEXT: .long 0
@nullptr23 = global i32 addrspace(23)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(23)*)
; CHECK-LABEL: structWithPointers:
; CHECK-NEXT: .long -1
; CHECK-NEXT: .zero 4
; CHECK-NEXT: .quad 0
; CHECK-NEXT: .quad 0
; CHECK-NEXT: .long -1
; CHECK-NEXT: .zero 4
; CHECK-NEXT: .quad 0
; CHECK-NEXT: .long -1
; CHECK-NEXT: .zero 4
@structWithPointers = addrspace(1) global %struct.S {
i32* addrspacecast (i32 addrspace(4)* null to i32*),
i32 addrspace(1)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(1)*),
i32 addrspace(2)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(2)*),
i32 addrspace(3)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(3)*),
i32 addrspace(4)* null,
i32 addrspace(5)* addrspacecast (i32 addrspace(4)* null to i32 addrspace(5)*)}, align 4