disas: Add subset of libvixl sources for A64 disassembler

Add the subset of the libvixl sources that are needed for the
A64 disassembler support. These sources come from
https://github.com/armvixl/vixl commit 578645f14e122d2b
which is VIXL release 1.1.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>

1 files changed, 238 insertions, 0 deletions

diff --git a/disas/libvixl/a64/instructions-a64.cc b/disas/libvixl/a64/instructions-a64.cc
new file mode 100644
index 0000000000..e87fa3acce
--- /dev/null
+++ b/disas/libvixl/a64/instructions-a64.cc
@@ -0,0 +1,238 @@
+// 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) {
+  ASSERT(width <= 64);
+  rotate &= 63;
+  return ((value & ((1UL << rotate) - 1UL)) << (width - rotate)) |
+         (value >> rotate);
+}
+
+
+static uint64_t RepeatBitsAcrossReg(unsigned reg_size,
+                                    uint64_t value,
+                                    unsigned width) {
+  ASSERT((width == 2) || (width == 4) || (width == 8) || (width == 16) ||
+         (width == 32));
+  ASSERT((reg_size == kWRegSize) || (reg_size == kXRegSize));
+  uint64_t result = value & ((1UL << width) - 1UL);
+  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 = (1UL << (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 = (1UL << ((imm_s & mask) + 1)) - 1;
+        return RepeatBitsAcrossReg(reg_size,
+                                   RotateRight(bits, imm_r & mask, width),
+                                   width);
+      }
+    }
+  }
+  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() {
+  ptrdiff_t offset;
+  if (IsPCRelAddressing()) {
+    // PC-relative addressing. Only ADR is supported.
+    offset = ImmPCRel();
+  } else {
+    // All PC-relative branches.
+    ASSERT(BranchType() != UnknownBranchType);
+    // Relative branch offsets are instruction-size-aligned.
+    offset = ImmBranch() << kInstructionSizeLog2;
+  }
+  return this + 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: UNREACHABLE();
+  }
+  return 0;
+}
+
+
+void Instruction::SetImmPCOffsetTarget(Instruction* target) {
+  if (IsPCRelAddressing()) {
+    SetPCRelImmTarget(target);
+  } else {
+    SetBranchImmTarget(target);
+  }
+}
+
+
+void Instruction::SetPCRelImmTarget(Instruction* target) {
+  // ADRP is not supported, so 'this' must point to an ADR instruction.
+  ASSERT(Mask(PCRelAddressingMask) == ADR);
+
+  Instr imm = Assembler::ImmPCRelAddress(target - this);
+
+  SetInstructionBits(Mask(~ImmPCRel_mask) | imm);
+}
+
+
+void Instruction::SetBranchImmTarget(Instruction* target) {
+  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: UNREACHABLE();
+  }
+  SetInstructionBits(Mask(~imm_mask) | branch_imm);
+}
+
+
+void Instruction::SetImmLLiteral(Instruction* source) {
+  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
+