xref: /third_party/vixl/src/aarch64/simulator-constants-aarch64.h

// Copyright 2015, VIXL authors
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#ifndef VIXL_AARCH64_SIMULATOR_CONSTANTS_AARCH64_H_
#define VIXL_AARCH64_SIMULATOR_CONSTANTS_AARCH64_H_

#include "instructions-aarch64.h"

namespace vixl {
namespace aarch64 {

// Debug instructions.
//
// VIXL's macro-assembler and simulator support a few pseudo instructions to
// make debugging easier. These pseudo instructions do not exist on real
// hardware.
//
// TODO: Also consider allowing these pseudo-instructions to be disabled in the
// simulator, so that users can check that the input is a valid native code.
// (This isn't possible in all cases. Printf won't work, for example.)
//
// Each debug pseudo instruction is represented by a HLT instruction. The HLT
// immediate field is used to identify the type of debug pseudo instruction.

enum DebugHltOpcode {
  kUnreachableOpcode = 0xdeb0,
  kPrintfOpcode,
  kTraceOpcode,
  kLogOpcode,
  kRuntimeCallOpcode,
  kSetCPUFeaturesOpcode,
  kEnableCPUFeaturesOpcode,
  kDisableCPUFeaturesOpcode,
  kSaveCPUFeaturesOpcode,
  kRestoreCPUFeaturesOpcode,
  kMTEActive,
  kMTEInactive,
  // Aliases.
  kDebugHltFirstOpcode = kUnreachableOpcode,
  kDebugHltLastOpcode = kLogOpcode
};
VIXL_DEPRECATED("DebugHltOpcode", typedef DebugHltOpcode DebugHltOpcodes);

// Each pseudo instruction uses a custom encoding for additional arguments, as
// described below.

// Unreachable - kUnreachableOpcode
//
// Instruction which should never be executed. This is used as a guard in parts
// of the code that should not be reachable, such as in data encoded inline in
// the instructions.

// Printf - kPrintfOpcode
//  - arg_count: The number of arguments.
//  - arg_pattern: A set of PrintfArgPattern values, packed into two-bit fields.
//
// Simulate a call to printf.
//
// Floating-point and integer arguments are passed in separate sets of registers
// in AAPCS64 (even for varargs functions), so it is not possible to determine
// the type of each argument without some information about the values that were
// passed in. This information could be retrieved from the printf format string,
// but the format string is not trivial to parse so we encode the relevant
// information with the HLT instruction.
//
// Also, the following registers are populated (as if for a native Aarch64
// call):
//    x0: The format string
// x1-x7: Optional arguments, if type == CPURegister::kRegister
// d0-d7: Optional arguments, if type == CPURegister::kVRegister
const unsigned kPrintfArgCountOffset = 1 * kInstructionSize;
const unsigned kPrintfArgPatternListOffset = 2 * kInstructionSize;
const unsigned kPrintfLength = 3 * kInstructionSize;

const unsigned kPrintfMaxArgCount = 4;

// The argument pattern is a set of two-bit-fields, each with one of the
// following values:
enum PrintfArgPattern {
  kPrintfArgW = 1,
  kPrintfArgX = 2,
  // There is no kPrintfArgS because floats are always converted to doubles in C
  // varargs calls.
  kPrintfArgD = 3
};
static const unsigned kPrintfArgPatternBits = 2;

// Trace - kTraceOpcode
//  - parameter: TraceParameter stored as a uint32_t
//  - command: TraceCommand stored as a uint32_t
//
// Allow for trace management in the generated code. This enables or disables
// automatic tracing of the specified information for every simulated
// instruction.
const unsigned kTraceParamsOffset = 1 * kInstructionSize;
const unsigned kTraceCommandOffset = 2 * kInstructionSize;
const unsigned kTraceLength = 3 * kInstructionSize;

// Trace parameters.
enum TraceParameters {
  LOG_DISASM = 1 << 0,   // Log disassembly.
  LOG_REGS = 1 << 1,     // Log general purpose registers.
  LOG_VREGS = 1 << 2,    // Log SVE, NEON and floating-point registers.
  LOG_SYSREGS = 1 << 3,  // Log the flags and system registers.
  LOG_WRITE = 1 << 4,    // Log writes to memory.
  LOG_BRANCH = 1 << 5,   // Log taken branches.

  LOG_NONE = 0,
  LOG_STATE = LOG_REGS | LOG_VREGS | LOG_SYSREGS,
  LOG_ALL = LOG_DISASM | LOG_STATE | LOG_WRITE | LOG_BRANCH
};

// Trace commands.
enum TraceCommand { TRACE_ENABLE = 1, TRACE_DISABLE = 2 };

// Log - kLogOpcode
//  - parameter: TraceParameter stored as a uint32_t
//
// Print the specified information once. This mechanism is separate from Trace.
// In particular, _all_ of the specified registers are printed, rather than just
// the registers that the instruction writes.
//
// Any combination of the TraceParameters values can be used, except that
// LOG_DISASM is not supported for Log.
const unsigned kLogParamsOffset = 1 * kInstructionSize;
const unsigned kLogLength = 2 * kInstructionSize;

// Runtime call simulation - kRuntimeCallOpcode
enum RuntimeCallType { kCallRuntime, kTailCallRuntime };

const unsigned kRuntimeCallWrapperOffset = 1 * kInstructionSize;
// The size of a pointer on host.
const unsigned kRuntimeCallAddressSize = sizeof(uintptr_t);
const unsigned kRuntimeCallFunctionOffset =
    kRuntimeCallWrapperOffset + kRuntimeCallAddressSize;
const unsigned kRuntimeCallTypeOffset =
    kRuntimeCallFunctionOffset + kRuntimeCallAddressSize;
const unsigned kRuntimeCallLength = kRuntimeCallTypeOffset + sizeof(uint32_t);

// Enable or disable CPU features - kSetCPUFeaturesOpcode
//                                - kEnableCPUFeaturesOpcode
//                                - kDisableCPUFeaturesOpcode
//  - parameter[...]: A list of `CPUFeatures::Feature`s, encoded as
//    ConfigureCPUFeaturesElementType and terminated with CPUFeatures::kNone.
//  - [Padding to align to kInstructionSize.]
//
// 'Set' completely overwrites the existing CPU features.
// 'Enable' and 'Disable' update the existing CPU features.
//
// These mechanisms allows users to strictly check the use of CPU features in
// different regions of code.
//
// These have no effect on the set of 'seen' features (as reported by
// CPUFeaturesAuditor::HasSeen(...)).
typedef uint8_t ConfigureCPUFeaturesElementType;
const unsigned kConfigureCPUFeaturesListOffset = 1 * kInstructionSize;

// Save or restore CPU features - kSaveCPUFeaturesOpcode
//                              - kRestoreCPUFeaturesOpcode
//
// These mechanisms provide a stack-like mechanism for preserving the CPU
// features, or restoring the last-preserved features. These pseudo-instructions
// take no arguments.
//
// These have no effect on the set of 'seen' features (as reported by
// CPUFeaturesAuditor::HasSeen(...)).

}  // namespace aarch64
}  // namespace vixl

#endif  // VIXL_AARCH64_SIMULATOR_CONSTANTS_AARCH64_H_