// -*- mode:c++ -*-
// Copyright (c) 2003-2005 The Regents of The University of Michigan
// 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 the copyright holders 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 AND 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.
//
// Authors: Steve Reinhardt
////////////////////////////////////////////////////////////////////
//
// Control transfer instructions
//
output header {{
/**
* Base class for instructions whose disassembly is not purely a
* function of the machine instruction (i.e., it depends on the
* PC). This class overrides the disassemble() method to check
* the PC and symbol table values before re-using a cached
* disassembly string. This is necessary for branches and jumps,
* where the disassembly string includes the target address (which
* may depend on the PC and/or symbol table).
*/
class PCDependentDisassembly : public AlphaStaticInst
{
protected:
/// Cached program counter from last disassembly
mutable Addr cachedPC;
/// Cached symbol table pointer from last disassembly
mutable const SymbolTable *cachedSymtab;
/// Constructor
PCDependentDisassembly(const char *mnem, ExtMachInst _machInst,
OpClass __opClass)
: AlphaStaticInst(mnem, _machInst, __opClass),
cachedPC(0), cachedSymtab(0)
{
}
const std::string &
disassemble(Addr pc, const SymbolTable *symtab) const;
};
/**
* Base class for branches (PC-relative control transfers),
* conditional or unconditional.
*/
class Branch : public PCDependentDisassembly
{
protected:
/// Displacement to target address (signed).
int32_t disp;
/// Constructor.
Branch(const char *mnem, ExtMachInst _machInst, OpClass __opClass)
: PCDependentDisassembly(mnem, _machInst, __opClass),
disp(BRDISP << 2)
{
}
AlphaISA::PCState branchTarget(const AlphaISA::PCState &branchPC) const;
std::string
generateDisassembly(Addr pc, const SymbolTable *symtab) const;
};
/**
* Base class for jumps (register-indirect control transfers). In
* the Alpha ISA, these are always unconditional.
*/
class Jump : public PCDependentDisassembly
{
protected:
/// Displacement to target address (signed).
int32_t disp;
public:
/// Constructor
Jump(const char *mnem, ExtMachInst _machInst, OpClass __opClass)
: PCDependentDisassembly(mnem, _machInst, __opClass),
disp(BRDISP)
{
}
AlphaISA::PCState branchTarget(ThreadContext *tc) const;
std::string
generateDisassembly(Addr pc, const SymbolTable *symtab) const;
};
}};
output decoder {{
AlphaISA::PCState
Branch::branchTarget(const AlphaISA::PCState &branchPC) const
{
return branchPC.pc() + 4 + disp;
}
AlphaISA::PCState
Jump::branchTarget(ThreadContext *tc) const
{
PCState pc = tc->pcState();
uint64_t Rb = tc->readIntReg(_srcRegIdx[0]);
pc.set((Rb & ~3) | (pc.pc() & 1));
return pc;
}
const std::string &
PCDependentDisassembly::disassemble(Addr pc,
const SymbolTable *symtab) const
{
if (!cachedDisassembly ||
pc != cachedPC || symtab != cachedSymtab)
{
if (cachedDisassembly)
delete cachedDisassembly;
cachedDisassembly =
new std::string(generateDisassembly(pc, symtab));
cachedPC = pc;
cachedSymtab = symtab;
}
return *cachedDisassembly;
}
std::string
Branch::generateDisassembly(Addr pc, const SymbolTable *symtab) const
{
std::stringstream ss;
ccprintf(ss, "%-10s ", mnemonic);
// There's only one register arg (RA), but it could be
// either a source (the condition for conditional
// branches) or a destination (the link reg for
// unconditional branches)
if (_numSrcRegs > 0) {
printReg(ss, _srcRegIdx[0]);
ss << ",";
}
else if (_numDestRegs > 0) {
printReg(ss, _destRegIdx[0]);
ss << ",";
}
#ifdef SS_COMPATIBLE_DISASSEMBLY
if (_numSrcRegs == 0 && _numDestRegs == 0) {
printReg(ss, 31);
ss << ",";
}
#endif
Addr target = pc + 4 + disp;
std::string str;
if (symtab && symtab->findSymbol(target, str))
ss << str;
else
ccprintf(ss, "0x%x", target);
return ss.str();
}
std::string
Jump::generateDisassembly(Addr pc, const SymbolTable *symtab) const
{
std::stringstream ss;
ccprintf(ss, "%-10s ", mnemonic);
#ifdef SS_COMPATIBLE_DISASSEMBLY
if (_numDestRegs == 0) {
printReg(ss, 31);
ss << ",";
}
#endif
if (_numDestRegs > 0) {
printReg(ss, _destRegIdx[0]);
ss << ",";
}
ccprintf(ss, "(r%d)", RB);
return ss.str();
}
}};
def template JumpOrBranchDecode {{
return (RA == 31)
? (StaticInst *)new %(class_name)s(machInst)
: (StaticInst *)new %(class_name)sAndLink(machInst);
}};
def format CondBranch(code) {{
code = '''
bool cond;
%(code)s;
if (cond)
NPC = NPC + disp;
else
NPC = NPC;
''' % { "code" : code }
iop = InstObjParams(name, Name, 'Branch', code,
('IsDirectControl', 'IsCondControl'))
header_output = BasicDeclare.subst(iop)
decoder_output = BasicConstructor.subst(iop)
decode_block = BasicDecode.subst(iop)
exec_output = BasicExecute.subst(iop)
}};
let {{
def UncondCtrlBase(name, Name, base_class, npc_expr, flags):
# Declare basic control transfer w/o link (i.e. link reg is R31)
nolink_code = 'NPC = %s;\n' % npc_expr
nolink_iop = InstObjParams(name, Name, base_class,
nolink_code, flags)
header_output = BasicDeclare.subst(nolink_iop)
decoder_output = BasicConstructor.subst(nolink_iop)
exec_output = BasicExecute.subst(nolink_iop)
# Generate declaration of '*AndLink' version, append to decls
link_code = 'Ra = NPC & ~3;\n' + nolink_code
link_iop = InstObjParams(name, Name + 'AndLink', base_class,
link_code, flags)
header_output += BasicDeclare.subst(link_iop)
decoder_output += BasicConstructor.subst(link_iop)
exec_output += BasicExecute.subst(link_iop)
# need to use link_iop for the decode template since it is expecting
# the shorter version of class_name (w/o "AndLink")
return (header_output, decoder_output,
JumpOrBranchDecode.subst(nolink_iop), exec_output)
}};
def format UncondBranch(*flags) {{
flags += ('IsUncondControl', 'IsDirectControl')
(header_output, decoder_output, decode_block, exec_output) = \
UncondCtrlBase(name, Name, 'Branch', 'NPC + disp', flags)
}};
def format Jump(*flags) {{
flags += ('IsUncondControl', 'IsIndirectControl')
(header_output, decoder_output, decode_block, exec_output) = \
UncondCtrlBase(name, Name, 'Jump', '(Rb & ~3) | (NPC & 1)', flags)
}};