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Materialize global addresses via movt/movw pair, this is always better

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than doing the same via constpool:
1. Load from constpool costs 3 cycles on A9, movt/movw pair - just 2.
2. Load from constpool might stall up to 300 cycles due to cache miss.
3. Movt/movw does not use load/store unit.
4. Less constpool entries => better compiler performance.

This is only enabled on ELF systems, since darwin does not have needed
relocations (yet).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89720 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Anton Korobeynikov 2009-11-24 00:44:37 +00:00
parent 6935efcb66
commit 5cdc3a949a
11 changed files with 147 additions and 41 deletions
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16
lib/Target/ARM/ARMBaseInstrInfo.h
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@ -162,6 +162,22 @@ namespace ARMII {
I_BitShift = 25,
CondShift = 28
};
/// Target Operand Flag enum.
enum TOF {
//===------------------------------------------------------------------===//
// ARM Specific MachineOperand flags.
MO_NO_FLAG,
/// MO_LO16 - On a symbol operand, this represents a relocation containing
/// lower 16 bit of the address. Used only via movw instruction.
MO_LO16,
/// MO_HI16 - On a symbol operand, this represents a relocation containing
/// higher 16 bit of the address. Used only via movt instruction.
MO_HI16
};
}
class ARMBaseInstrInfo : public TargetInstrInfoImpl {

33
lib/Target/ARM/ARMExpandPseudoInsts.cpp
View File

@ -75,17 +75,30 @@ bool ARMExpandPseudo::ExpandMBB(MachineBasicBlock &MBB) {
}
case ARM::t2MOVi32imm: {
unsigned DstReg = MI.getOperand(0).getReg();
unsigned Imm = MI.getOperand(1).getImm();
unsigned Lo16 = Imm & 0xffff;
unsigned Hi16 = (Imm >> 16) & 0xffff;
if (!MI.getOperand(0).isDead()) {
AddDefaultPred(BuildMI(MBB, MBBI, MI.getDebugLoc(),
TII->get(ARM::t2MOVi16), DstReg)
.addImm(Lo16));
AddDefaultPred(BuildMI(MBB, MBBI, MI.getDebugLoc(),
TII->get(ARM::t2MOVTi16))
.addReg(DstReg, getDefRegState(true))
.addReg(DstReg).addImm(Hi16));
const MachineOperand &MO = MI.getOperand(1);
MachineInstrBuilder LO16, HI16;
LO16 = BuildMI(MBB, MBBI, MI.getDebugLoc(), TII->get(ARM::t2MOVi16),
DstReg);
HI16 = BuildMI(MBB, MBBI, MI.getDebugLoc(), TII->get(ARM::t2MOVTi16))
.addReg(DstReg, getDefRegState(true)).addReg(DstReg);
if (MO.isImm()) {
unsigned Imm = MO.getImm();
unsigned Lo16 = Imm & 0xffff;
unsigned Hi16 = (Imm >> 16) & 0xffff;
LO16 = LO16.addImm(Lo16);
HI16 = HI16.addImm(Hi16);
} else {
GlobalValue *GV = MO.getGlobal();
unsigned TF = MO.getTargetFlags();
LO16 = LO16.addGlobalAddress(GV, MO.getOffset(), TF | ARMII::MO_LO16);
HI16 = HI16.addGlobalAddress(GV, MO.getOffset(), TF | ARMII::MO_HI16);
// FIXME: What's about memoperands?
}
AddDefaultPred(LO16);
AddDefaultPred(HI16);
}
MI.eraseFromParent();
Modified = true;

20
lib/Target/ARM/ARMISelDAGToDAG.cpp
View File

@ -261,7 +261,9 @@ bool ARMDAGToDAGISel::SelectAddrMode2(SDValue Op, SDValue N,
if (N.getOpcode() == ISD::FrameIndex) {
int FI = cast<FrameIndexSDNode>(N)->getIndex();
Base = CurDAG->getTargetFrameIndex(FI, TLI.getPointerTy());
} else if (N.getOpcode() == ARMISD::Wrapper) {
} else if (N.getOpcode() == ARMISD::Wrapper &&
!(Subtarget->useMovt() &&
N.getOperand(0).getOpcode() == ISD::TargetGlobalAddress)) {
Base = N.getOperand(0);
}
Offset = CurDAG->getRegister(0, MVT::i32);
@ -463,7 +465,9 @@ bool ARMDAGToDAGISel::SelectAddrMode5(SDValue Op, SDValue N,
if (N.getOpcode() == ISD::FrameIndex) {
int FI = cast<FrameIndexSDNode>(N)->getIndex();
Base = CurDAG->getTargetFrameIndex(FI, TLI.getPointerTy());
} else if (N.getOpcode() == ARMISD::Wrapper) {
} else if (N.getOpcode() == ARMISD::Wrapper &&
!(Subtarget->useMovt() &&
N.getOperand(0).getOpcode() == ISD::TargetGlobalAddress)) {
Base = N.getOperand(0);
}
Offset = CurDAG->getTargetConstant(ARM_AM::getAM5Opc(ARM_AM::add, 0),
@ -558,7 +562,13 @@ ARMDAGToDAGISel::SelectThumbAddrModeRI5(SDValue Op, SDValue N,
}
if (N.getOpcode() != ISD::ADD) {
Base = (N.getOpcode() == ARMISD::Wrapper) ? N.getOperand(0) : N;
if (N.getOpcode() == ARMISD::Wrapper &&
!(Subtarget->useMovt() &&
N.getOperand(0).getOpcode() == ISD::TargetGlobalAddress)) {
Base = N.getOperand(0);
} else
Base = N;
Offset = CurDAG->getRegister(0, MVT::i32);
OffImm = CurDAG->getTargetConstant(0, MVT::i32);
return true;
@ -681,7 +691,9 @@ bool ARMDAGToDAGISel::SelectT2AddrModeImm12(SDValue Op, SDValue N,
Base = CurDAG->getTargetFrameIndex(FI, TLI.getPointerTy());
OffImm = CurDAG->getTargetConstant(0, MVT::i32);
return true;
} else if (N.getOpcode() == ARMISD::Wrapper) {
} else if (N.getOpcode() == ARMISD::Wrapper &&
!(Subtarget->useMovt() &&
N.getOperand(0).getOpcode() == ISD::TargetGlobalAddress)) {
Base = N.getOperand(0);
if (Base.getOpcode() == ISD::TargetConstantPool)
return false; // We want to select t2LDRpci instead.

16
lib/Target/ARM/ARMISelLowering.cpp
View File

@ -39,6 +39,7 @@
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/ADT/VectorExtras.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include <sstream>
@ -1356,10 +1357,17 @@ SDValue ARMTargetLowering::LowerGlobalAddressELF(SDValue Op,
PseudoSourceValue::getGOT(), 0);
return Result;
} else {
SDValue CPAddr = DAG.getTargetConstantPool(GV, PtrVT, 4);
CPAddr = DAG.getNode(ARMISD::Wrapper, dl, MVT::i32, CPAddr);
return DAG.getLoad(PtrVT, dl, DAG.getEntryNode(), CPAddr,
PseudoSourceValue::getConstantPool(), 0);
// If we have T2 ops, we can materialize the address directly via movt/movw
// pair. This is always cheaper.
if (Subtarget->useMovt()) {
return DAG.getNode(ARMISD::Wrapper, dl, PtrVT,
DAG.getTargetGlobalAddress(GV, PtrVT));
} else {
SDValue CPAddr = DAG.getTargetConstantPool(GV, PtrVT, 4);
CPAddr = DAG.getNode(ARMISD::Wrapper, dl, MVT::i32, CPAddr);
return DAG.getLoad(PtrVT, dl, DAG.getEntryNode(), CPAddr,
PseudoSourceValue::getConstantPool(), 0);
}
}
}

25
lib/Target/ARM/ARMInstrInfo.td
View File

@ -116,6 +116,10 @@ def IsNotDarwin : Predicate<"!Subtarget->isTargetDarwin()">;
def CarryDefIsUnused : Predicate<"!N.getNode()->hasAnyUseOfValue(1)">;
def CarryDefIsUsed : Predicate<"N.getNode()->hasAnyUseOfValue(1)">;
// FIXME: Eventually this will be just "hasV6T2Ops".
def UseMovt : Predicate<"Subtarget->useMovt()">;
def DontUseMovt : Predicate<"!Subtarget->useMovt()">;
//===----------------------------------------------------------------------===//
// ARM Flag Definitions.
@ -204,7 +208,7 @@ def hi16 : SDNodeXForm<imm, [{
def lo16AllZero : PatLeaf<(i32 imm), [{
// Returns true if all low 16-bits are 0.
return (((uint32_t)N->getZExtValue()) & 0xFFFFUL) == 0;
}], hi16>;
}], hi16>;
/// imm0_65535 predicate - True if the 32-bit immediate is in the range
/// [0.65535].
@ -1002,7 +1006,7 @@ def MOVi16 : AI1<0b1000, (outs GPR:$dst), (ins i32imm:$src),
let Constraints = "$src = $dst" in
def MOVTi16 : AI1<0b1010, (outs GPR:$dst), (ins GPR:$src, i32imm:$imm),
DPFrm, IIC_iMOVi,
"movt", "\t$dst, $imm",
"movt", "\t$dst, $imm",
[(set GPR:$dst,
(or (and GPR:$src, 0xffff),
lo16AllZero:$imm))]>, UnaryDP,
@ -1603,12 +1607,6 @@ let Defs =
// Non-Instruction Patterns
//
// ConstantPool, GlobalAddress, and JumpTable
def : ARMPat<(ARMWrapper tglobaladdr :$dst), (LEApcrel tglobaladdr :$dst)>;
def : ARMPat<(ARMWrapper tconstpool :$dst), (LEApcrel tconstpool :$dst)>;
def : ARMPat<(ARMWrapperJT tjumptable:$dst, imm:$id),
(LEApcrelJT tjumptable:$dst, imm:$id)>;
// Large immediate handling.
// Two piece so_imms.
@ -1638,10 +1636,19 @@ def : ARMPat<(add GPR:$LHS, so_neg_imm2part:$RHS),
// FIXME: Remove this when we can do generalized remat.
let isReMaterializable = 1 in
def MOVi32imm : AI1x2<(outs GPR:$dst), (ins i32imm:$src), Pseudo, IIC_iMOVi,
"movw", "\t$dst, ${src:lo16}\n\tmovt${p} $dst, ${src:hi16}",
"movw", "\t$dst, ${src:lo16}\n\tmovt${p}\t$dst, ${src:hi16}",
[(set GPR:$dst, (i32 imm:$src))]>,
Requires<[IsARM, HasV6T2]>;
// ConstantPool, GlobalAddress, and JumpTable
def : ARMPat<(ARMWrapper tglobaladdr :$dst), (LEApcrel tglobaladdr :$dst)>,
Requires<[IsARM, DontUseMovt]>;
def : ARMPat<(ARMWrapper tconstpool :$dst), (LEApcrel tconstpool :$dst)>;
def : ARMPat<(ARMWrapper tglobaladdr :$dst), (MOVi32imm tglobaladdr :$dst)>,
Requires<[IsARM, UseMovt]>;
def : ARMPat<(ARMWrapperJT tjumptable:$dst, imm:$id),
(LEApcrelJT tjumptable:$dst, imm:$id)>;
// TODO: add,sub,and, 3-instr forms?

16
lib/Target/ARM/ARMInstrThumb2.td
View File

@ -1181,12 +1181,6 @@ def : T2Pat<(add GPR:$LHS, t2_so_neg_imm2part:$RHS),
(t2SUBri (t2SUBri GPR:$LHS, (t2_so_neg_imm2part_1 imm:$RHS)),
(t2_so_neg_imm2part_2 imm:$RHS))>;
// ConstantPool, GlobalAddress, and JumpTable
def : T2Pat<(ARMWrapper tglobaladdr :$dst), (t2LEApcrel tglobaladdr :$dst)>;
def : T2Pat<(ARMWrapper tconstpool :$dst), (t2LEApcrel tconstpool :$dst)>;
def : T2Pat<(ARMWrapperJT tjumptable:$dst, imm:$id),
(t2LEApcrelJT tjumptable:$dst, imm:$id)>;
// 32-bit immediate using movw + movt.
// This is a single pseudo instruction to make it re-materializable. Remove
// when we can do generalized remat.
@ -1195,6 +1189,16 @@ def t2MOVi32imm : T2Ix2<(outs GPR:$dst), (ins i32imm:$src), IIC_iMOVi,
"movw", "\t$dst, ${src:lo16}\n\tmovt${p}\t$dst, ${src:hi16}",
[(set GPR:$dst, (i32 imm:$src))]>;
// ConstantPool, GlobalAddress, and JumpTable
def : T2Pat<(ARMWrapper tglobaladdr :$dst), (t2LEApcrel tglobaladdr :$dst)>,
Requires<[IsThumb2, DontUseMovt]>;
def : T2Pat<(ARMWrapper tconstpool :$dst), (t2LEApcrel tconstpool :$dst)>;
def : T2Pat<(ARMWrapper tglobaladdr :$dst), (t2MOVi32imm tglobaladdr :$dst)>,
Requires<[IsThumb2, UseMovt]>;
def : T2Pat<(ARMWrapperJT tjumptable:$dst, imm:$id),
(t2LEApcrelJT tjumptable:$dst, imm:$id)>;
// Pseudo instruction that combines ldr from constpool and add pc. This should
// be expanded into two instructions late to allow if-conversion and
// scheduling.

5
lib/Target/ARM/ARMSubtarget.cpp
View File

@ -27,6 +27,10 @@ UseNEONFP("arm-use-neon-fp",
cl::desc("Use NEON for single-precision FP"),
cl::init(false), cl::Hidden);
static cl::opt<bool>
UseMOVT("arm-use-movt",
cl::init(true), cl::Hidden);
ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &FS,
bool isT)
: ARMArchVersion(V4T)
@ -36,6 +40,7 @@ ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &FS,
, ThumbMode(Thumb1)
, PostRAScheduler(false)
, IsR9Reserved(ReserveR9)
, UseMovt(UseMOVT)
, stackAlignment(4)
, CPUString("generic")
, TargetType(isELF) // Default to ELF unless otherwise specified.

8
lib/Target/ARM/ARMSubtarget.h
View File

@ -65,6 +65,10 @@ protected:
/// IsR9Reserved - True if R9 is a not available as general purpose register.
bool IsR9Reserved;
/// UseMovt - True if MOVT / MOVW pairs are used for materialization of 32-bit
/// imms (including global addresses).
bool UseMovt;
/// stackAlignment - The minimum alignment known to hold of the stack frame on
/// entry to the function and which must be maintained by every function.
unsigned stackAlignment;
@ -130,8 +134,10 @@ protected:
bool isR9Reserved() const { return IsR9Reserved; }
bool useMovt() const { return UseMovt && hasV6T2Ops(); }
const std::string & getCPUString() const { return CPUString; }
/// enablePostRAScheduler - True at 'More' optimization.
bool enablePostRAScheduler(CodeGenOpt::Level OptLevel,
TargetSubtarget::AntiDepBreakMode& Mode,

21
lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp
View File

@ -330,6 +330,8 @@ bool ARMAsmPrinter::runOnMachineFunction(MachineFunction &MF) {
void ARMAsmPrinter::printOperand(const MachineInstr *MI, int OpNum,
const char *Modifier) {
const MachineOperand &MO = MI->getOperand(OpNum);
unsigned TF = MO.getTargetFlags();
switch (MO.getType()) {
default:
assert(0 && "<unknown operand type>");
@ -356,12 +358,12 @@ void ARMAsmPrinter::printOperand(const MachineInstr *MI, int OpNum,
case MachineOperand::MO_Immediate: {
int64_t Imm = MO.getImm();
O << '#';
if (Modifier) {
if (strcmp(Modifier, "lo16") == 0)
O << ":lower16:";
else if (strcmp(Modifier, "hi16") == 0)
O << ":upper16:";
}
if ((Modifier && strcmp(Modifier, "lo16") == 0) ||
(TF & ARMII::MO_LO16))
O << ":lower16:";
else if ((Modifier && strcmp(Modifier, "hi16") == 0) ||
(TF & ARMII::MO_HI16))
O << ":upper16:";
O << Imm;
break;
}
@ -371,6 +373,13 @@ void ARMAsmPrinter::printOperand(const MachineInstr *MI, int OpNum,
case MachineOperand::MO_GlobalAddress: {
bool isCallOp = Modifier && !strcmp(Modifier, "call");
GlobalValue *GV = MO.getGlobal();
if ((Modifier && strcmp(Modifier, "lo16") == 0) ||
(TF & ARMII::MO_LO16))
O << ":lower16:";
else if ((Modifier && strcmp(Modifier, "hi16") == 0) ||
(TF & ARMII::MO_HI16))
O << ":upper16:";
O << Mang->getMangledName(GV);
printOffset(MO.getOffset());

8
lib/Target/ARM/Thumb2SizeReduction.cpp
View File

@ -78,7 +78,7 @@ namespace {
{ ARM::t2LSRri, ARM::tLSRri, 0, 5, 0, 1, 0, 0,0, 0 },
{ ARM::t2LSRrr, 0, ARM::tLSRrr, 0, 0, 0, 1, 0,0, 0 },
{ ARM::t2MOVi, ARM::tMOVi8, 0, 8, 0, 1, 0, 0,0, 0 },
{ ARM::t2MOVi16,ARM::tMOVi8, 0, 8, 0, 1, 0, 0,0, 0 },
{ ARM::t2MOVi16,ARM::tMOVi8, 0, 8, 0, 1, 0, 0,0, 1 },
// FIXME: Do we need the 16-bit 'S' variant?
{ ARM::t2MOVr,ARM::tMOVgpr2gpr,0, 0, 0, 0, 0, 1,0, 0 },
{ ARM::t2MOVCCr,0, ARM::tMOVCCr, 0, 0, 0, 0, 0,1, 0 },
@ -413,6 +413,12 @@ Thumb2SizeReduce::ReduceSpecial(MachineBasicBlock &MBB, MachineInstr *MI,
if (MI->getOperand(2).getImm() == 0)
return ReduceToNarrow(MBB, MI, Entry, LiveCPSR);
break;
case ARM::t2MOVi16:
// Can convert only 'pure' immediate operands, not immediates obtained as
// globals' addresses.
if (MI->getOperand(1).isImm())
return ReduceToNarrow(MBB, MI, Entry, LiveCPSR);
break;
}
return false;
}

20
test/CodeGen/ARM/movt-movw-global.ll Normal file
View File

@ -0,0 +1,20 @@
; RUN: llc < %s | FileCheck %s
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64"
target triple = "armv7-eabi"
@foo = common global i32 0 ; <i32*> [#uses=1]
define arm_aapcs_vfpcc i32* @bar1() nounwind readnone {
entry:
; CHECK: movw r0, :lower16:foo
; CHECK-NEXT: movt r0, :upper16:foo
ret i32* @foo
}
define arm_aapcs_vfpcc void @bar2(i32 %baz) nounwind {
entry:
; CHECK: movw r1, :lower16:foo
; CHECK-NEXT: movt r1, :upper16:foo
store i32 %baz, i32* @foo, align 4
ret void
}