llvm-6502/lib/Target/ARM/ARMAddressingModes.h
Evan Cheng 6495f63945 - More refactoring. This gets rid of all of the getOpcode calls.
- This change also makes it possible to switch between ARM / Thumb on a
  per-function basis.
- Fixed thumb2 routine which expand reg + arbitrary immediate. It was using
  using ARM so_imm logic.
- Use movw and movt to do reg + imm when profitable.
- Other code clean ups and minor optimizations.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77300 91177308-0d34-0410-b5e6-96231b3b80d8
2009-07-28 05:48:47 +00:00

506 lines
17 KiB
C++

//===- ARMAddressingModes.h - ARM Addressing Modes --------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the ARM addressing mode implementation stuff.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TARGET_ARM_ARMADDRESSINGMODES_H
#define LLVM_TARGET_ARM_ARMADDRESSINGMODES_H
#include "llvm/CodeGen/SelectionDAGNodes.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include <cassert>
namespace llvm {
/// ARM_AM - ARM Addressing Mode Stuff
namespace ARM_AM {
enum ShiftOpc {
no_shift = 0,
asr,
lsl,
lsr,
ror,
rrx
};
enum AddrOpc {
add = '+', sub = '-'
};
static inline const char *getShiftOpcStr(ShiftOpc Op) {
switch (Op) {
default: llvm_unreachable("Unknown shift opc!");
case ARM_AM::asr: return "asr";
case ARM_AM::lsl: return "lsl";
case ARM_AM::lsr: return "lsr";
case ARM_AM::ror: return "ror";
case ARM_AM::rrx: return "rrx";
}
}
static inline ShiftOpc getShiftOpcForNode(SDValue N) {
switch (N.getOpcode()) {
default: return ARM_AM::no_shift;
case ISD::SHL: return ARM_AM::lsl;
case ISD::SRL: return ARM_AM::lsr;
case ISD::SRA: return ARM_AM::asr;
case ISD::ROTR: return ARM_AM::ror;
//case ISD::ROTL: // Only if imm -> turn into ROTR.
// Can't handle RRX here, because it would require folding a flag into
// the addressing mode. :( This causes us to miss certain things.
//case ARMISD::RRX: return ARM_AM::rrx;
}
}
enum AMSubMode {
bad_am_submode = 0,
ia,
ib,
da,
db
};
static inline const char *getAMSubModeStr(AMSubMode Mode) {
switch (Mode) {
default: llvm_unreachable("Unknown addressing sub-mode!");
case ARM_AM::ia: return "ia";
case ARM_AM::ib: return "ib";
case ARM_AM::da: return "da";
case ARM_AM::db: return "db";
}
}
static inline const char *getAMSubModeAltStr(AMSubMode Mode, bool isLD) {
switch (Mode) {
default: llvm_unreachable("Unknown addressing sub-mode!");
case ARM_AM::ia: return isLD ? "fd" : "ea";
case ARM_AM::ib: return isLD ? "ed" : "fa";
case ARM_AM::da: return isLD ? "fa" : "ed";
case ARM_AM::db: return isLD ? "ea" : "fd";
}
}
/// rotr32 - Rotate a 32-bit unsigned value right by a specified # bits.
///
static inline unsigned rotr32(unsigned Val, unsigned Amt) {
assert(Amt < 32 && "Invalid rotate amount");
return (Val >> Amt) | (Val << ((32-Amt)&31));
}
/// rotl32 - Rotate a 32-bit unsigned value left by a specified # bits.
///
static inline unsigned rotl32(unsigned Val, unsigned Amt) {
assert(Amt < 32 && "Invalid rotate amount");
return (Val << Amt) | (Val >> ((32-Amt)&31));
}
//===--------------------------------------------------------------------===//
// Addressing Mode #1: shift_operand with registers
//===--------------------------------------------------------------------===//
//
// This 'addressing mode' is used for arithmetic instructions. It can
// represent things like:
// reg
// reg [asr|lsl|lsr|ror|rrx] reg
// reg [asr|lsl|lsr|ror|rrx] imm
//
// This is stored three operands [rega, regb, opc]. The first is the base
// reg, the second is the shift amount (or reg0 if not present or imm). The
// third operand encodes the shift opcode and the imm if a reg isn't present.
//
static inline unsigned getSORegOpc(ShiftOpc ShOp, unsigned Imm) {
return ShOp | (Imm << 3);
}
static inline unsigned getSORegOffset(unsigned Op) {
return Op >> 3;
}
static inline ShiftOpc getSORegShOp(unsigned Op) {
return (ShiftOpc)(Op & 7);
}
/// getSOImmValImm - Given an encoded imm field for the reg/imm form, return
/// the 8-bit imm value.
static inline unsigned getSOImmValImm(unsigned Imm) {
return Imm & 0xFF;
}
/// getSOImmValRot - Given an encoded imm field for the reg/imm form, return
/// the rotate amount.
static inline unsigned getSOImmValRot(unsigned Imm) {
return (Imm >> 8) * 2;
}
/// getSOImmValRotate - Try to handle Imm with an immediate shifter operand,
/// computing the rotate amount to use. If this immediate value cannot be
/// handled with a single shifter-op, determine a good rotate amount that will
/// take a maximal chunk of bits out of the immediate.
static inline unsigned getSOImmValRotate(unsigned Imm) {
// 8-bit (or less) immediates are trivially shifter_operands with a rotate
// of zero.
if ((Imm & ~255U) == 0) return 0;
// Use CTZ to compute the rotate amount.
unsigned TZ = CountTrailingZeros_32(Imm);
// Rotate amount must be even. Something like 0x200 must be rotated 8 bits,
// not 9.
unsigned RotAmt = TZ & ~1;
// If we can handle this spread, return it.
if ((rotr32(Imm, RotAmt) & ~255U) == 0)
return (32-RotAmt)&31; // HW rotates right, not left.
// For values like 0xF000000F, we should skip the first run of ones, then
// retry the hunt.
if (Imm & 1) {
unsigned TrailingOnes = CountTrailingZeros_32(~Imm);
if (TrailingOnes != 32) { // Avoid overflow on 0xFFFFFFFF
// Restart the search for a high-order bit after the initial seconds of
// ones.
unsigned TZ2 = CountTrailingZeros_32(Imm & ~((1 << TrailingOnes)-1));
// Rotate amount must be even.
unsigned RotAmt2 = TZ2 & ~1;
// If this fits, use it.
if (RotAmt2 != 32 && (rotr32(Imm, RotAmt2) & ~255U) == 0)
return (32-RotAmt2)&31; // HW rotates right, not left.
}
}
// Otherwise, we have no way to cover this span of bits with a single
// shifter_op immediate. Return a chunk of bits that will be useful to
// handle.
return (32-RotAmt)&31; // HW rotates right, not left.
}
/// getSOImmVal - Given a 32-bit immediate, if it is something that can fit
/// into an shifter_operand immediate operand, return the 12-bit encoding for
/// it. If not, return -1.
static inline int getSOImmVal(unsigned Arg) {
// 8-bit (or less) immediates are trivially shifter_operands with a rotate
// of zero.
if ((Arg & ~255U) == 0) return Arg;
unsigned RotAmt = getSOImmValRotate(Arg);
// If this cannot be handled with a single shifter_op, bail out.
if (rotr32(~255U, RotAmt) & Arg)
return -1;
// Encode this correctly.
return rotl32(Arg, RotAmt) | ((RotAmt>>1) << 8);
}
/// isSOImmTwoPartVal - Return true if the specified value can be obtained by
/// or'ing together two SOImmVal's.
static inline bool isSOImmTwoPartVal(unsigned V) {
// If this can be handled with a single shifter_op, bail out.
V = rotr32(~255U, getSOImmValRotate(V)) & V;
if (V == 0)
return false;
// If this can be handled with two shifter_op's, accept.
V = rotr32(~255U, getSOImmValRotate(V)) & V;
return V == 0;
}
/// getSOImmTwoPartFirst - If V is a value that satisfies isSOImmTwoPartVal,
/// return the first chunk of it.
static inline unsigned getSOImmTwoPartFirst(unsigned V) {
return rotr32(255U, getSOImmValRotate(V)) & V;
}
/// getSOImmTwoPartSecond - If V is a value that satisfies isSOImmTwoPartVal,
/// return the second chunk of it.
static inline unsigned getSOImmTwoPartSecond(unsigned V) {
// Mask out the first hunk.
V = rotr32(~255U, getSOImmValRotate(V)) & V;
// Take what's left.
assert(V == (rotr32(255U, getSOImmValRotate(V)) & V));
return V;
}
/// getThumbImmValShift - Try to handle Imm with a 8-bit immediate followed
/// by a left shift. Returns the shift amount to use.
static inline unsigned getThumbImmValShift(unsigned Imm) {
// 8-bit (or less) immediates are trivially immediate operand with a shift
// of zero.
if ((Imm & ~255U) == 0) return 0;
// Use CTZ to compute the shift amount.
return CountTrailingZeros_32(Imm);
}
/// isThumbImmShiftedVal - Return true if the specified value can be obtained
/// by left shifting a 8-bit immediate.
static inline bool isThumbImmShiftedVal(unsigned V) {
// If this can be handled with
V = (~255U << getThumbImmValShift(V)) & V;
return V == 0;
}
/// getThumbImm16ValShift - Try to handle Imm with a 16-bit immediate followed
/// by a left shift. Returns the shift amount to use.
static inline unsigned getThumbImm16ValShift(unsigned Imm) {
// 16-bit (or less) immediates are trivially immediate operand with a shift
// of zero.
if ((Imm & ~65535U) == 0) return 0;
// Use CTZ to compute the shift amount.
return CountTrailingZeros_32(Imm);
}
/// isThumbImm16ShiftedVal - Return true if the specified value can be
/// obtained by left shifting a 16-bit immediate.
static inline bool isThumbImm16ShiftedVal(unsigned V) {
// If this can be handled with
V = (~65535U << getThumbImm16ValShift(V)) & V;
return V == 0;
}
/// getThumbImmNonShiftedVal - If V is a value that satisfies
/// isThumbImmShiftedVal, return the non-shiftd value.
static inline unsigned getThumbImmNonShiftedVal(unsigned V) {
return V >> getThumbImmValShift(V);
}
/// getT2SOImmValSplat - Return the 12-bit encoded representation
/// if the specified value can be obtained by splatting the low 8 bits
/// into every other byte or every byte of a 32-bit value. i.e.,
/// 00000000 00000000 00000000 abcdefgh control = 0
/// 00000000 abcdefgh 00000000 abcdefgh control = 1
/// abcdefgh 00000000 abcdefgh 00000000 control = 2
/// abcdefgh abcdefgh abcdefgh abcdefgh control = 3
/// Return -1 if none of the above apply.
/// See ARM Reference Manual A6.3.2.
static inline int getT2SOImmValSplatVal(unsigned V) {
unsigned u, Vs, Imm;
// control = 0
if ((V & 0xffffff00) == 0)
return V;
// If the value is zeroes in the first byte, just shift those off
Vs = ((V & 0xff) == 0) ? V >> 8 : V;
// Any passing value only has 8 bits of payload, splatted across the word
Imm = Vs & 0xff;
// Likewise, any passing values have the payload splatted into the 3rd byte
u = Imm | (Imm << 16);
// control = 1 or 2
if (Vs == u)
return (((Vs == V) ? 1 : 2) << 8) | Imm;
// control = 3
if (Vs == (u | (u << 8)))
return (3 << 8) | Imm;
return -1;
}
/// getT2SOImmValRotateVal - Return the 12-bit encoded representation if the
/// specified value is a rotated 8-bit value. Return -1 if no rotation
/// encoding is possible.
/// See ARM Reference Manual A6.3.2.
static inline int getT2SOImmValRotateVal(unsigned V) {
unsigned RotAmt = CountLeadingZeros_32(V);
if (RotAmt >= 24)
return -1;
// If 'Arg' can be handled with a single shifter_op return the value.
if ((rotr32(0xff000000U, RotAmt) & V) == V)
return (rotr32(V, 24 - RotAmt) & 0x7f) | ((RotAmt + 8) << 7);
return -1;
}
/// getT2SOImmVal - Given a 32-bit immediate, if it is something that can fit
/// into a Thumb-2 shifter_operand immediate operand, return the 12-bit
/// encoding for it. If not, return -1.
/// See ARM Reference Manual A6.3.2.
static inline int getT2SOImmVal(unsigned Arg) {
// If 'Arg' is an 8-bit splat, then get the encoded value.
int Splat = getT2SOImmValSplatVal(Arg);
if (Splat != -1)
return Splat;
// If 'Arg' can be handled with a single shifter_op return the value.
int Rot = getT2SOImmValRotateVal(Arg);
if (Rot != -1)
return Rot;
return -1;
}
//===--------------------------------------------------------------------===//
// Addressing Mode #2
//===--------------------------------------------------------------------===//
//
// This is used for most simple load/store instructions.
//
// addrmode2 := reg +/- reg shop imm
// addrmode2 := reg +/- imm12
//
// The first operand is always a Reg. The second operand is a reg if in
// reg/reg form, otherwise it's reg#0. The third field encodes the operation
// in bit 12, the immediate in bits 0-11, and the shift op in 13-15.
//
// If this addressing mode is a frame index (before prolog/epilog insertion
// and code rewriting), this operand will have the form: FI#, reg0, <offs>
// with no shift amount for the frame offset.
//
static inline unsigned getAM2Opc(AddrOpc Opc, unsigned Imm12, ShiftOpc SO) {
assert(Imm12 < (1 << 12) && "Imm too large!");
bool isSub = Opc == sub;
return Imm12 | ((int)isSub << 12) | (SO << 13);
}
static inline unsigned getAM2Offset(unsigned AM2Opc) {
return AM2Opc & ((1 << 12)-1);
}
static inline AddrOpc getAM2Op(unsigned AM2Opc) {
return ((AM2Opc >> 12) & 1) ? sub : add;
}
static inline ShiftOpc getAM2ShiftOpc(unsigned AM2Opc) {
return (ShiftOpc)(AM2Opc >> 13);
}
//===--------------------------------------------------------------------===//
// Addressing Mode #3
//===--------------------------------------------------------------------===//
//
// This is used for sign-extending loads, and load/store-pair instructions.
//
// addrmode3 := reg +/- reg
// addrmode3 := reg +/- imm8
//
// The first operand is always a Reg. The second operand is a reg if in
// reg/reg form, otherwise it's reg#0. The third field encodes the operation
// in bit 8, the immediate in bits 0-7.
/// getAM3Opc - This function encodes the addrmode3 opc field.
static inline unsigned getAM3Opc(AddrOpc Opc, unsigned char Offset) {
bool isSub = Opc == sub;
return ((int)isSub << 8) | Offset;
}
static inline unsigned char getAM3Offset(unsigned AM3Opc) {
return AM3Opc & 0xFF;
}
static inline AddrOpc getAM3Op(unsigned AM3Opc) {
return ((AM3Opc >> 8) & 1) ? sub : add;
}
//===--------------------------------------------------------------------===//
// Addressing Mode #4
//===--------------------------------------------------------------------===//
//
// This is used for load / store multiple instructions.
//
// addrmode4 := reg, <mode>
//
// The four modes are:
// IA - Increment after
// IB - Increment before
// DA - Decrement after
// DB - Decrement before
//
// If the 4th bit (writeback)is set, then the base register is updated after
// the memory transfer.
static inline AMSubMode getAM4SubMode(unsigned Mode) {
return (AMSubMode)(Mode & 0x7);
}
static inline unsigned getAM4ModeImm(AMSubMode SubMode, bool WB = false) {
return (int)SubMode | ((int)WB << 3);
}
static inline bool getAM4WBFlag(unsigned Mode) {
return (Mode >> 3) & 1;
}
//===--------------------------------------------------------------------===//
// Addressing Mode #5
//===--------------------------------------------------------------------===//
//
// This is used for coprocessor instructions, such as FP load/stores.
//
// addrmode5 := reg +/- imm8*4
//
// The first operand is always a Reg. The second operand encodes the
// operation in bit 8 and the immediate in bits 0-7.
//
// This is also used for FP load/store multiple ops. The second operand
// encodes the writeback mode in bit 8 and the number of registers (or 2
// times the number of registers for DPR ops) in bits 0-7. In addition,
// bits 9-11 encode one of the following two sub-modes:
//
// IA - Increment after
// DB - Decrement before
/// getAM5Opc - This function encodes the addrmode5 opc field.
static inline unsigned getAM5Opc(AddrOpc Opc, unsigned char Offset) {
bool isSub = Opc == sub;
return ((int)isSub << 8) | Offset;
}
static inline unsigned char getAM5Offset(unsigned AM5Opc) {
return AM5Opc & 0xFF;
}
static inline AddrOpc getAM5Op(unsigned AM5Opc) {
return ((AM5Opc >> 8) & 1) ? sub : add;
}
/// getAM5Opc - This function encodes the addrmode5 opc field for FLDM and
/// FSTM instructions.
static inline unsigned getAM5Opc(AMSubMode SubMode, bool WB,
unsigned char Offset) {
assert((SubMode == ia || SubMode == db) &&
"Illegal addressing mode 5 sub-mode!");
return ((int)SubMode << 9) | ((int)WB << 8) | Offset;
}
static inline AMSubMode getAM5SubMode(unsigned AM5Opc) {
return (AMSubMode)((AM5Opc >> 9) & 0x7);
}
static inline bool getAM5WBFlag(unsigned AM5Opc) {
return ((AM5Opc >> 8) & 1);
}
//===--------------------------------------------------------------------===//
// Addressing Mode #6
//===--------------------------------------------------------------------===//
//
// This is used for NEON load / store instructions.
//
// addrmode6 := reg with optional writeback
//
// This is stored in three operands [regaddr, regupdate, opc]. The first is
// the address register. The second register holds the value of a post-access
// increment for writeback or reg0 if no writeback or if the writeback
// increment is the size of the memory access. The third operand encodes
// whether there is writeback to the address register.
static inline unsigned getAM6Opc(bool WB = false) {
return (int)WB;
}
static inline bool getAM6WBFlag(unsigned Mode) {
return Mode & 1;
}
} // end namespace ARM_AM
} // end namespace llvm
#endif