assembler.hpp

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#ifndef SHARE_ASM_ASSEMBLER_HPP
#defineSHARE_ASM_ASSEMBLER_HPP

#include"asm/codeBuffer.hpp"
#include"asm/register.hpp"
#include"code/oopRecorder.hpp"
#include"code/relocInfo.hpp"
#include"memory/allocation.hpp"
#include"utilities/checkedCast.hpp"
#include"utilities/debug.hpp"
#include"utilities/growableArray.hpp"
#include"utilities/macros.hpp"

// This file contains platform-independent assembler declarations.

classMacroAssembler;
classAbstractAssembler;
classLabel;

/**
 * Labels represent destinations for control transfer instructions. Such
 * instructions can accept a Label as their target argument. A Label is
 * bound to the current location in the code stream by calling the
 * MacroAssembler's 'bind' method, which in turn calls the Label's 'bind'
 * method. A Label may be referenced by an instruction before it's bound
 * (i.e., 'forward referenced'). 'bind' stores the current code offset
 * in the Label object.
 *
 * If an instruction references a bound Label, the offset field(s) within
 * the instruction are immediately filled in based on the Label's code
 * offset. If an instruction references an unbound label, that
 * instruction is put on a list of instructions that must be patched
 * (i.e., 'resolved') when the Label is bound.
 *
 * 'bind' will call the platform-specific 'patch_instruction' method to
 * fill in the offset field(s) for each unresolved instruction (if there
 * are any). 'patch_instruction' lives in one of the
 * cpu/<arch>/vm/assembler_<arch>* files.
 *
 * Instead of using a linked list of unresolved instructions, a Label has
 * an array of unresolved instruction code offsets. _patch_index
 * contains the total number of forward references. If the Label's array
 * overflows (i.e., _patch_index grows larger than the array size), a
 * GrowableArray is allocated to hold the remaining offsets. (The cache
 * size is 4 for now, which handles over 99.5% of the cases)
 *
 * Labels may only be used within a single CodeSection. If you need
 * to create references between code sections, use explicit relocations.
*/
classLabel {
private:
enum { PatchCacheSize = 4DEBUG_ONLY( +4 ) };

// _loc encodes both the binding state (via its sign)
// and the binding locator (via its value) of a label.
//
// _loc >= 0 bound label, loc() encodes the target (jump) position
// _loc == -1 unbound label
int _loc;

// References to instructions that jump to this unresolved label.
// These instructions need to be patched when the label is bound
// using the platform-specific patchInstruction() method.
//
// To avoid having to allocate from the C-heap each time, we provide
// a local cache and use the overflow only if we exceed the local cache
int _patches[PatchCacheSize];
int _patch_index;
 GrowableArray<int>* _patch_overflow;

NONCOPYABLE(Label);
protected:

// The label will be bound to a location near its users.
bool _is_near;

#ifdef ASSERT
// Sourcre file and line location of jump instruction
int _lines[PatchCacheSize];
constchar* _files[PatchCacheSize];
#endif
public:

/**
 * After binding, be sure 'patch_instructions' is called later to link
*/
voidbind_loc(int loc) {
assert(loc >= 0, "illegal locator");
assert(_loc == -1, "already bound");
 _loc = loc;
 }
voidbind_loc(int pos, int sect) { bind_loc(CodeBuffer::locator(pos, sect)); }

#ifndef PRODUCT
// Iterates over all unresolved instructions for printing
voidprint_instructions(MacroAssembler* masm) const;
#endif// PRODUCT

/**
 * Returns the position of the Label in the code buffer
 * The position is a 'locator', which encodes both offset and section.
*/
intloc() const {
assert(_loc >= 0, "unbound label");
return _loc;
 }
intloc_pos() const { returnCodeBuffer::locator_pos(loc()); }
intloc_sect() const { returnCodeBuffer::locator_sect(loc()); }

boolis_bound() const { return _loc >= 0; }
boolis_unbound() const { return _loc == -1 && _patch_index > 0; }
boolis_unused() const { return _loc == -1 && _patch_index == 0; }

// The label will be bound to a location near its users. Users can
// optimize on this information, e.g. generate short branches.
boolis_near() { return _is_near; }

/**
 * Adds a reference to an unresolved displacement instruction to
 * this unbound label
 *
 * @param cb the code buffer being patched
 * @param branch_loc the locator of the branch instruction in the code buffer
*/
voidadd_patch_at(CodeBuffer* cb, int branch_loc, constchar* file = nullptr, int line = 0);

/**
 * Iterate over the list of patches, resolving the instructions
 * Call patch_instruction on each 'branch_loc' value
*/
voidpatch_instructions(MacroAssembler* masm);

voidinit() {
 _loc = -1;
 _patch_index = 0;
 _patch_overflow = nullptr;
 _is_near = false;
 }

Label() {
init();
 }

~Label() {
assert(is_bound() || is_unused(), "Label was never bound to a location, but it was used as a jmp target");
 }

voidreset() {
init(); //leave _patch_overflow because it points to CodeBuffer.
 }
};

// A NearLabel must be bound to a location near its users. Users can
// optimize on this information, e.g. generate short branches.
classNearLabel : publicLabel {
public:
NearLabel() : Label() { _is_near = true; }
};

// A union type for code which has to assemble both constant and
// non-constant operands, when the distinction cannot be made
// statically.
classRegisterOrConstant {
private:
 Register _r;
intptr_t _c;

public:
RegisterOrConstant(): _r(noreg), _c(0) {}
RegisterOrConstant(Register r): _r(r), _c(0) {}
RegisterOrConstant(intptr_t c): _r(noreg), _c(c) {}

 Register as_register() const { assert(is_register(),""); return _r; }
intptr_tas_constant() const { assert(is_constant(),""); return _c; }

 Register register_or_noreg() const { return _r; }
intptr_tconstant_or_zero() const { return _c; }

boolis_register() const { return _r != noreg; }
boolis_constant() const { return _r == noreg; }
};

// The Abstract Assembler: Pure assembler doing NO optimizations on the
// instruction level; i.e., what you write is what you get.
// The Assembler is generating code into a CodeBuffer.
classAbstractAssembler : publicResourceObj {
friendclassLabel;

protected:
 CodeSection* _code_section; // section within the code buffer
 OopRecorder* _oop_recorder; // support for relocInfo::oop_type

public:
// Code emission & accessing
 address addr_at(int pos) const { returncode_section()->start() + pos; }

protected:
// This routine is called with a label is used for an address.
// Labels and displacements truck in offsets, but target must return a PC.
 address target(Label& L) { returncode_section()->target(L, pc()); }

boolis8bit(int x) const { return -0x80 <= x && x < 0x80; }
boolisByte(int x) const { return0 <= x && x < 0x100; }
boolisShiftCount(int x) const { return0 <= x && x < 32; }

// Mark instruction boundaries, this is required when emitting relocatable values.
// Basically, all instructions that directly or indirectly use Assembler::emit_data* methods.
classInstructionMark: publicStackObj {
private:
 AbstractAssembler* _assm;

public:
InstructionMark(AbstractAssembler* assm) : _assm(assm) {
assert(assm->inst_mark() == nullptr, "overlapping instructions");
 _assm->set_inst_mark();
 }
~InstructionMark() {
 _assm->clear_inst_mark();
 }
 };
friendclassInstructionMark;

public:
// count size of instructions which are skipped from inline heuristics
classInlineSkippedInstructionsCounter: publicStackObj {
private:
 AbstractAssembler* _assm;
 address _start;
public:
InlineSkippedInstructionsCounter(AbstractAssembler* assm) : _assm(assm), _start(assm->pc()) {
 }
~InlineSkippedInstructionsCounter() {
 _assm->register_skipped(checked_cast<int>(_assm->pc() - _start));
 }
 };

protected:
#ifdef ASSERT
// Make it return true on platforms which need to verify
// instruction boundaries for some operations.
staticboolpd_check_instruction_mark();

// Add delta to short branch distance to verify that it still fit into imm8.
int _short_branch_delta;

intshort_branch_delta() const { return _short_branch_delta; }
voidset_short_branch_delta() { _short_branch_delta = 32; }
voidclear_short_branch_delta() { _short_branch_delta = 0; }

classShortBranchVerifier: publicStackObj {
private:
 AbstractAssembler* _assm;

public:
ShortBranchVerifier(AbstractAssembler* assm) : _assm(assm) {
assert(assm->short_branch_delta() == 0, "overlapping instructions");
 _assm->set_short_branch_delta();
 }
~ShortBranchVerifier() {
 _assm->clear_short_branch_delta();
 }
 };
#else
// Dummy in product.
classShortBranchVerifier: publicStackObj {
public:
ShortBranchVerifier(AbstractAssembler* assm) {}
 };
#endif

// sign-extended tolerant cast needed by callers of emit_int8 and emit_int16
// Some callers pass signed types that need to fit into the unsigned type so check
// that the range is correct.
template <typename T>
constexpr T narrow_cast(int x) const {
if (x < 0) {
using stype = std::make_signed_t<T>;
assert(x >= std::numeric_limits<stype>::min(), "too negative"); // >= -128 for 8 bits
returnstatic_cast<T>(x); // cut off sign bits
 } else {
return checked_cast<T>(x);
 }
 }

public:

// Creation
AbstractAssembler(CodeBuffer* code);

// ensure buf contains all code (call this before using/copying the code)
voidflush();

voidemit_int8( int x1) { code_section()->emit_int8(narrow_cast<uint8_t>(x1)); }

voidemit_int16( int x) { code_section()->emit_int16(narrow_cast<uint16_t>(x)); }

voidemit_int16( int x1, int x2) { code_section()->emit_int16(narrow_cast<uint8_t>(x1),
 narrow_cast<uint8_t>(x2)); }

voidemit_int24( int x1, int x2, int x3) { code_section()->emit_int24(narrow_cast<uint8_t>(x1),
 narrow_cast<uint8_t>(x2),
 narrow_cast<uint8_t>(x3)); }

voidemit_int32( uint32_t x) { code_section()->emit_int32(x); }
voidemit_int32( int x1, int x2, int x3, int x4) { code_section()->emit_int32(narrow_cast<uint8_t>(x1),
 narrow_cast<uint8_t>(x2),
 narrow_cast<uint8_t>(x3),
 narrow_cast<uint8_t>(x4)); }

voidemit_int64( uint64_t x) { code_section()->emit_int64(x); }

voidemit_float( jfloat x) { code_section()->emit_float(x); }
voidemit_double( jdouble x) { code_section()->emit_double(x); }
voidemit_address(address x) { code_section()->emit_address(x); }

enum { min_simm10 = -512 };

// Test if x is within signed immediate range for width.
staticboolis_simm(int64_t x, uint w) {
precond(1 < w && w < 64);
int64_t limes = INT64_C(1) << (w - 1);
return -limes <= x && x < limes;
 }

staticboolis_simm8(int64_t x) { returnis_simm(x, 8); }
staticboolis_simm9(int64_t x) { returnis_simm(x, 9); }
staticboolis_simm10(int64_t x) { returnis_simm(x, 10); }
staticboolis_simm16(int64_t x) { returnis_simm(x, 16); }
staticboolis_simm32(int64_t x) { returnis_simm(x, 32); }

// Test if x is within unsigned immediate range for width.
staticboolis_uimm(uint64_t x, uint w) {
precond(0 < w && w < 64);
uint64_t limes = UINT64_C(1) << w;
return x < limes;
 }

staticboolis_uimm12(uint64_t x) { returnis_uimm(x, 12); }
staticboolis_uimm32(uint64_t x) { returnis_uimm(x, 32); }

// Accessors
 CodeSection* code_section() const { return _code_section; }
 CodeBuffer* code() const { returncode_section()->outer(); }
intsect() const { returncode_section()->index(); }
 address pc() const { returncode_section()->end(); }
 address begin() const { returncode_section()->start(); }
intoffset() const { returncode_section()->size(); }
intlocator() const { returnCodeBuffer::locator(offset(), sect()); }

 OopRecorder* oop_recorder() const { return _oop_recorder; }
voidset_oop_recorder(OopRecorder* r) { _oop_recorder = r; }

voidregister_skipped(int size) { code_section()->register_skipped(size); }

 address inst_mark() const { returncode_section()->mark(); }
voidset_inst_mark() { code_section()->set_mark(); }
voidset_inst_mark(address addr) { code_section()->set_mark(addr); }
voidclear_inst_mark() { code_section()->clear_mark(); }
voidset_inst_end(address addr) { code_section()->set_end(addr); }

// Constants in code
voidrelocate(RelocationHolder const& rspec, int format = 0) {
assert(!pd_check_instruction_mark()
 || inst_mark() == nullptr || inst_mark() == code_section()->end(),
"call relocate() between instructions");
code_section()->relocate(code_section()->end(), rspec, format);
 }
voidrelocate( relocInfo::relocType rtype, int format = 0) {
code_section()->relocate(code_section()->end(), rtype, format);
 }
voidrelocate(address addr, relocInfo::relocType rtype, int format = 0) {
code_section()->relocate(addr, rtype, format);
 }
voidrelocate(address addr, RelocationHolder const& rspec, int format = 0) {
code_section()->relocate(addr, rspec, format);
 }

staticintcode_fill_byte(); // used to pad out odd-sized code buffers

// Associate a comment with the current offset. It will be printed
// along with the disassembly when printing nmethods. Currently
// only supported in the instruction section of the code buffer.
voidblock_comment(constchar* comment);
// Copy str to a buffer that has the same lifetime as the CodeBuffer
constchar* code_string(constchar* str);

// Label functions
voidbind(Label& L); // binds an unbound label L to the current code position

// Move to a different section in the same code buffer.
voidset_code_section(CodeSection* cs);

// Inform assembler when generating stub code and relocation info
 address start_a_stub(int required_space);
voidend_a_stub();
// Ditto for constants.
 address start_a_const(int required_space, int required_align = sizeof(double));
voidend_a_const(CodeSection* cs); // Pass the codesection to continue in (insts or stubs?).

// constants support
//
// We must remember the code section (insts or stubs) in c1
// so we can reset to the proper section in end_a_const().
 address int_constant(jint c) {
 CodeSection* c1 = _code_section;
 address ptr = start_a_const(sizeof(c), sizeof(c));
if (ptr != nullptr) {
emit_int32(c);
end_a_const(c1);
 }
return ptr;
 }
 address long_constant(jlong c) {
 CodeSection* c1 = _code_section;
 address ptr = start_a_const(sizeof(c), sizeof(c));
if (ptr != nullptr) {
emit_int64(c);
end_a_const(c1);
 }
return ptr;
 }
 address double_constant(jdouble c) {
 CodeSection* c1 = _code_section;
 address ptr = start_a_const(sizeof(c), sizeof(c));
if (ptr != nullptr) {
emit_double(c);
end_a_const(c1);
 }
return ptr;
 }
 address float_constant(jfloat c) {
 CodeSection* c1 = _code_section;
 address ptr = start_a_const(sizeof(c), sizeof(c));
if (ptr != nullptr) {
emit_float(c);
end_a_const(c1);
 }
return ptr;
 }
 address address_constant(address c) {
 CodeSection* c1 = _code_section;
 address ptr = start_a_const(sizeof(c), sizeof(c));
if (ptr != nullptr) {
emit_address(c);
end_a_const(c1);
 }
return ptr;
 }
 address address_constant(address c, RelocationHolder const& rspec) {
 CodeSection* c1 = _code_section;
 address ptr = start_a_const(sizeof(c), sizeof(c));
if (ptr != nullptr) {
relocate(rspec);
emit_address(c);
end_a_const(c1);
 }
return ptr;
 }
 address array_constant(const GrowableArray<jbyte>* c, int alignment) {
 CodeSection* c1 = _code_section;
 address ptr = start_a_const(c->length(), alignment);
if (ptr != nullptr) {
for (int i = 0; i < c->length(); i++) {
emit_int8(c->at(i));
 }
end_a_const(c1);
 }
return ptr;
 }

// Bang stack to trigger StackOverflowError at a safe location
// implementation delegates to machine-specific bang_stack_with_offset
voidgenerate_stack_overflow_check( int frame_size_in_bytes );
virtualvoidbang_stack_with_offset(int offset) = 0;


/**
 * A platform-dependent method to patch a jump instruction that refers
 * to this label.
 *
 * @param branch the location of the instruction to patch
 * @param masm the assembler which generated the branch
*/
voidpd_patch_instruction(address branch, address target, constchar* file, int line);

};

#include CPU_HEADER(assembler)

#endif// SHARE_ASM_ASSEMBLER_HPP