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Diffstat (limited to 'src/arch/alpha/isa/branch.isa')
| -rw-r--r-- | src/arch/alpha/isa/branch.isa | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/src/arch/alpha/isa/branch.isa b/src/arch/alpha/isa/branch.isa new file mode 100644 index 000000000..b528df938 --- /dev/null +++ b/src/arch/alpha/isa/branch.isa @@ -0,0 +1,259 @@ +// -*- 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. + +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) + { + } + + Addr branchTarget(Addr 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) + { + } + + Addr branchTarget(ExecContext *xc) const; + + std::string + generateDisassembly(Addr pc, const SymbolTable *symtab) const; + }; +}}; + +output decoder {{ + Addr + Branch::branchTarget(Addr branchPC) const + { + return branchPC + 4 + disp; + } + + Addr + Jump::branchTarget(ExecContext *xc) const + { + Addr NPC = xc->readPC() + 4; + uint64_t Rb = xc->readIntReg(_srcRegIdx[0]); + return (Rb & ~3) | (NPC & 1); + } + + 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;\n' + code + '\nif (cond) NPC = NPC + disp;\n'; + iop = InstObjParams(name, Name, 'Branch', CodeBlock(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, + CodeBlock(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, + CodeBlock(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) +}}; + + |