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// Copyright 2013, ARM Limited
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of ARM Limited nor the names of its contributors may be
// used to endorse or promote products derived from this software without
// specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "a64/instructions-a64.h"
#include "a64/assembler-a64.h"
namespace vixl {
static uint64_t RotateRight(uint64_t value,
unsigned int rotate,
unsigned int width) {
VIXL_ASSERT(width <= 64);
rotate &= 63;
return ((value & ((UINT64_C(1) << rotate) - 1)) <<
(width - rotate)) | (value >> rotate);
}
static uint64_t RepeatBitsAcrossReg(unsigned reg_size,
uint64_t value,
unsigned width) {
VIXL_ASSERT((width == 2) || (width == 4) || (width == 8) || (width == 16) ||
(width == 32));
VIXL_ASSERT((reg_size == kWRegSize) || (reg_size == kXRegSize));
uint64_t result = value & ((UINT64_C(1) << width) - 1);
for (unsigned i = width; i < reg_size; i *= 2) {
result |= (result << i);
}
return result;
}
// Logical immediates can't encode zero, so a return value of zero is used to
// indicate a failure case. Specifically, where the constraints on imm_s are
// not met.
uint64_t Instruction::ImmLogical() {
unsigned reg_size = SixtyFourBits() ? kXRegSize : kWRegSize;
int64_t n = BitN();
int64_t imm_s = ImmSetBits();
int64_t imm_r = ImmRotate();
// An integer is constructed from the n, imm_s and imm_r bits according to
// the following table:
//
// N imms immr size S R
// 1 ssssss rrrrrr 64 UInt(ssssss) UInt(rrrrrr)
// 0 0sssss xrrrrr 32 UInt(sssss) UInt(rrrrr)
// 0 10ssss xxrrrr 16 UInt(ssss) UInt(rrrr)
// 0 110sss xxxrrr 8 UInt(sss) UInt(rrr)
// 0 1110ss xxxxrr 4 UInt(ss) UInt(rr)
// 0 11110s xxxxxr 2 UInt(s) UInt(r)
// (s bits must not be all set)
//
// A pattern is constructed of size bits, where the least significant S+1
// bits are set. The pattern is rotated right by R, and repeated across a
// 32 or 64-bit value, depending on destination register width.
//
if (n == 1) {
if (imm_s == 0x3F) {
return 0;
}
uint64_t bits = (UINT64_C(1) << (imm_s + 1)) - 1;
return RotateRight(bits, imm_r, 64);
} else {
if ((imm_s >> 1) == 0x1F) {
return 0;
}
for (int width = 0x20; width >= 0x2; width >>= 1) {
if ((imm_s & width) == 0) {
int mask = width - 1;
if ((imm_s & mask) == mask) {
return 0;
}
uint64_t bits = (UINT64_C(1) << ((imm_s & mask) + 1)) - 1;
return RepeatBitsAcrossReg(reg_size,
RotateRight(bits, imm_r & mask, width),
width);
}
}
}
VIXL_UNREACHABLE();
return 0;
}
float Instruction::ImmFP32() {
// ImmFP: abcdefgh (8 bits)
// Single: aBbb.bbbc.defg.h000.0000.0000.0000.0000 (32 bits)
// where B is b ^ 1
uint32_t bits = ImmFP();
uint32_t bit7 = (bits >> 7) & 0x1;
uint32_t bit6 = (bits >> 6) & 0x1;
uint32_t bit5_to_0 = bits & 0x3f;
uint32_t result = (bit7 << 31) | ((32 - bit6) << 25) | (bit5_to_0 << 19);
return rawbits_to_float(result);
}
double Instruction::ImmFP64() {
// ImmFP: abcdefgh (8 bits)
// Double: aBbb.bbbb.bbcd.efgh.0000.0000.0000.0000
// 0000.0000.0000.0000.0000.0000.0000.0000 (64 bits)
// where B is b ^ 1
uint32_t bits = ImmFP();
uint64_t bit7 = (bits >> 7) & 0x1;
uint64_t bit6 = (bits >> 6) & 0x1;
uint64_t bit5_to_0 = bits & 0x3f;
uint64_t result = (bit7 << 63) | ((256 - bit6) << 54) | (bit5_to_0 << 48);
return rawbits_to_double(result);
}
LSDataSize CalcLSPairDataSize(LoadStorePairOp op) {
switch (op) {
case STP_x:
case LDP_x:
case STP_d:
case LDP_d: return LSDoubleWord;
default: return LSWord;
}
}
Instruction* Instruction::ImmPCOffsetTarget() {
Instruction * base = this;
ptrdiff_t offset;
if (IsPCRelAddressing()) {
// ADR and ADRP.
offset = ImmPCRel();
if (Mask(PCRelAddressingMask) == ADRP) {
base = AlignDown(base, kPageSize);
offset *= kPageSize;
} else {
VIXL_ASSERT(Mask(PCRelAddressingMask) == ADR);
}
} else {
// All PC-relative branches.
VIXL_ASSERT(BranchType() != UnknownBranchType);
// Relative branch offsets are instruction-size-aligned.
offset = ImmBranch() << kInstructionSizeLog2;
}
return base + offset;
}
inline int Instruction::ImmBranch() const {
switch (BranchType()) {
case CondBranchType: return ImmCondBranch();
case UncondBranchType: return ImmUncondBranch();
case CompareBranchType: return ImmCmpBranch();
case TestBranchType: return ImmTestBranch();
default: VIXL_UNREACHABLE();
}
return 0;
}
void Instruction::SetImmPCOffsetTarget(Instruction* target) {
if (IsPCRelAddressing()) {
SetPCRelImmTarget(target);
} else {
SetBranchImmTarget(target);
}
}
void Instruction::SetPCRelImmTarget(Instruction* target) {
int32_t imm21;
if ((Mask(PCRelAddressingMask) == ADR)) {
imm21 = target - this;
} else {
VIXL_ASSERT(Mask(PCRelAddressingMask) == ADRP);
uintptr_t this_page = reinterpret_cast<uintptr_t>(this) / kPageSize;
uintptr_t target_page = reinterpret_cast<uintptr_t>(target) / kPageSize;
imm21 = target_page - this_page;
}
Instr imm = Assembler::ImmPCRelAddress(imm21);
SetInstructionBits(Mask(~ImmPCRel_mask) | imm);
}
void Instruction::SetBranchImmTarget(Instruction* target) {
VIXL_ASSERT(((target - this) & 3) == 0);
Instr branch_imm = 0;
uint32_t imm_mask = 0;
int offset = (target - this) >> kInstructionSizeLog2;
switch (BranchType()) {
case CondBranchType: {
branch_imm = Assembler::ImmCondBranch(offset);
imm_mask = ImmCondBranch_mask;
break;
}
case UncondBranchType: {
branch_imm = Assembler::ImmUncondBranch(offset);
imm_mask = ImmUncondBranch_mask;
break;
}
case CompareBranchType: {
branch_imm = Assembler::ImmCmpBranch(offset);
imm_mask = ImmCmpBranch_mask;
break;
}
case TestBranchType: {
branch_imm = Assembler::ImmTestBranch(offset);
imm_mask = ImmTestBranch_mask;
break;
}
default: VIXL_UNREACHABLE();
}
SetInstructionBits(Mask(~imm_mask) | branch_imm);
}
void Instruction::SetImmLLiteral(Instruction* source) {
VIXL_ASSERT(((source - this) & 3) == 0);
int offset = (source - this) >> kLiteralEntrySizeLog2;
Instr imm = Assembler::ImmLLiteral(offset);
Instr mask = ImmLLiteral_mask;
SetInstructionBits(Mask(~mask) | imm);
}
} // namespace vixl
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