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/*
* Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#ifndef SHARE_ASM_ASSEMBLER_HPP
#define SHARE_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/debug.hpp"
#include "utilities/growableArray.hpp"
#include "utilities/macros.hpp"
// This file contains platform-independent assembler declarations.
class MacroAssembler;
class AbstractAssembler;
class Label;
/**
* 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.
*/
class Label {
private:
enum { PatchCacheSize = 4 debug_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];
const char* _files[PatchCacheSize];
#endif
public:
/**
* After binding, be sure 'patch_instructions' is called later to link
*/
void bind_loc(int loc) {
assert(loc >= 0, "illegal locator");
assert(_loc == -1, "already bound");
_loc = loc;
}
void bind_loc(int pos, int sect) { bind_loc(CodeBuffer::locator(pos, sect)); }
#ifndef PRODUCT
// Iterates over all unresolved instructions for printing
void print_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.
*/
int loc() const {
assert(_loc >= 0, "unbound label");
return _loc;
}
int loc_pos() const { return CodeBuffer::locator_pos(loc()); }
int loc_sect() const { return CodeBuffer::locator_sect(loc()); }
bool is_bound() const { return _loc >= 0; }
bool is_unbound() const { return _loc == -1 && _patch_index > 0; }
bool is_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.
bool is_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
*/
void add_patch_at(CodeBuffer* cb, int branch_loc, const char* file = NULL, int line = 0);
/**
* Iterate over the list of patches, resolving the instructions
* Call patch_instruction on each 'branch_loc' value
*/
void patch_instructions(MacroAssembler* masm);
void init() {
_loc = -1;
_patch_index = 0;
_patch_overflow = NULL;
_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");
}
void reset() {
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.
class NearLabel : public Label {
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.
class RegisterOrConstant {
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_t as_constant() const { assert(is_constant(),""); return _c; }
Register register_or_noreg() const { return _r; }
intptr_t constant_or_zero() const { return _c; }
bool is_register() const { return _r != noreg; }
bool is_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.
class AbstractAssembler : public ResourceObj {
friend class Label;
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 { return code_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) { return code_section()->target(L, pc()); }
bool is8bit(int x) const { return -0x80 <= x && x < 0x80; }
bool isByte(int x) const { return 0 <= x && x < 0x100; }
bool isShiftCount(int x) const { return 0 <= x && x < 32; }
// Instruction boundaries (required when emitting relocatable values).
class InstructionMark: public StackObj {
private:
AbstractAssembler* _assm;
public:
InstructionMark(AbstractAssembler* assm) : _assm(assm) {
assert(assm->inst_mark() == NULL, "overlapping instructions");
_assm->set_inst_mark();
}
~InstructionMark() {
_assm->clear_inst_mark();
}
};
friend class InstructionMark;
#ifdef ASSERT
// Make it return true on platforms which need to verify
// instruction boundaries for some operations.
static bool pd_check_instruction_mark();
// Add delta to short branch distance to verify that it still fit into imm8.
int _short_branch_delta;
int short_branch_delta() const { return _short_branch_delta; }
void set_short_branch_delta() { _short_branch_delta = 32; }
void clear_short_branch_delta() { _short_branch_delta = 0; }
class ShortBranchVerifier: public StackObj {
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.
class ShortBranchVerifier: public StackObj {
public:
ShortBranchVerifier(AbstractAssembler* assm) {}
};
#endif
public:
// Creation
AbstractAssembler(CodeBuffer* code);
// ensure buf contains all code (call this before using/copying the code)
void flush();
void emit_int8( uint8_t x1) { code_section()->emit_int8(x1); }
void emit_int16( uint16_t x) { code_section()->emit_int16(x); }
void emit_int16( uint8_t x1, uint8_t x2) { code_section()->emit_int16(x1, x2); }
void emit_int24( uint8_t x1, uint8_t x2, uint8_t x3) { code_section()->emit_int24(x1, x2, x3); }
void emit_int32( uint32_t x) { code_section()->emit_int32(x); }
void emit_int32( uint8_t x1, uint8_t x2, uint8_t x3, uint8_t x4) { code_section()->emit_int32(x1, x2, x3, x4); }
void emit_int64( uint64_t x) { code_section()->emit_int64(x); }
void emit_float( jfloat x) { code_section()->emit_float(x); }
void emit_double( jdouble x) { code_section()->emit_double(x); }
void emit_address(address x) { code_section()->emit_address(x); }
enum { min_simm10 = -512 };
// Test if x is within signed immediate range for width.
static bool is_simm(int64_t x, uint w) {
precond(1 < w && w < 64);
int64_t limes = INT64_C(1) << (w - 1);
return -limes <= x && x < limes;
}
static bool is_simm8(int64_t x) { return is_simm(x, 8); }
static bool is_simm9(int64_t x) { return is_simm(x, 9); }
static bool is_simm10(int64_t x) { return is_simm(x, 10); }
static bool is_simm16(int64_t x) { return is_simm(x, 16); }
static bool is_simm32(int64_t x) { return is_simm(x, 32); }
// Test if x is within unsigned immediate range for width.
static bool is_uimm(uint64_t x, uint w) {
precond(0 < w && w < 64);
uint64_t limes = UINT64_C(1) << w;
return x < limes;
}
static bool is_uimm12(uint64_t x) { return is_uimm(x, 12); }
// Accessors
CodeSection* code_section() const { return _code_section; }
CodeBuffer* code() const { return code_section()->outer(); }
int sect() const { return code_section()->index(); }
address pc() const { return code_section()->end(); }
int offset() const { return code_section()->size(); }
int locator() const { return CodeBuffer::locator(offset(), sect()); }
OopRecorder* oop_recorder() const { return _oop_recorder; }
void set_oop_recorder(OopRecorder* r) { _oop_recorder = r; }
address inst_mark() const { return code_section()->mark(); }
void set_inst_mark() { code_section()->set_mark(); }
void clear_inst_mark() { code_section()->clear_mark(); }
// Constants in code
void relocate(RelocationHolder const& rspec, int format = 0) {
assert(!pd_check_instruction_mark()
|| inst_mark() == NULL || inst_mark() == code_section()->end(),
"call relocate() between instructions");
code_section()->relocate(code_section()->end(), rspec, format);
}
void relocate( relocInfo::relocType rtype, int format = 0) {
code_section()->relocate(code_section()->end(), rtype, format);
}
static int code_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.
void block_comment(const char* comment);
// Copy str to a buffer that has the same lifetime as the CodeBuffer
const char* code_string(const char* str);
// Label functions
void bind(Label& L); // binds an unbound label L to the current code position
// Move to a different section in the same code buffer.
void set_code_section(CodeSection* cs);
// Inform assembler when generating stub code and relocation info
address start_a_stub(int required_space);
void end_a_stub();
// Ditto for constants.
address start_a_const(int required_space, int required_align = sizeof(double));
void end_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 != NULL) {
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 != NULL) {
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 != NULL) {
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 != NULL) {
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 != NULL) {
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 != NULL) {
relocate(rspec);
emit_address(c);
end_a_const(c1);
}
return ptr;
}
address array_constant(BasicType bt, GrowableArray<jvalue>* c, int alignment) {
CodeSection* c1 = _code_section;
int len = c->length();
int size = type2aelembytes(bt) * len;
address ptr = start_a_const(size, alignment);
if (ptr != NULL) {
for (int i = 0; i < len; i++) {
jvalue e = c->at(i);
switch(bt) {
case T_BOOLEAN: emit_int8(e.z); break;
case T_BYTE: emit_int8(e.b); break;
case T_CHAR: emit_int16(e.c); break;
case T_SHORT: emit_int16(e.s); break;
case T_INT: emit_int32(e.i); break;
case T_LONG: emit_int64(e.j); break;
case T_FLOAT: emit_float(e.f); break;
case T_DOUBLE: emit_double(e.d); break;
default:
ShouldNotReachHere();
}
}
end_a_const(c1);
}
return ptr;
}
// Bang stack to trigger StackOverflowError at a safe location
// implementation delegates to machine-specific bang_stack_with_offset
void generate_stack_overflow_check( int frame_size_in_bytes );
virtual void bang_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
*/
void pd_patch_instruction(address branch, address target, const char* file, int line);
};
#include CPU_HEADER(assembler)
#endif // SHARE_ASM_ASSEMBLER_HPP
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