diff options
Diffstat (limited to 'src/arch/mips/isa/formats/branch.isa')
| -rw-r--r-- | src/arch/mips/isa/formats/branch.isa | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/src/arch/mips/isa/formats/branch.isa b/src/arch/mips/isa/formats/branch.isa new file mode 100644 index 000000000..827e3ccf0 --- /dev/null +++ b/src/arch/mips/isa/formats/branch.isa @@ -0,0 +1,278 @@ +// -*- mode:c++ -*- + +// Copyright (c) 2003-2006 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: Korey Sewell + +//////////////////////////////////////////////////////////////////// +// +// Control transfer instructions +// + +output header {{ + +#include <iostream> + using namespace std; + + /** + * 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 MipsStaticInst + { + 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, MachInst _machInst, + OpClass __opClass) + : MipsStaticInst(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: + /// target address (signed) Displacement . + int32_t disp; + + /// Constructor. + Branch(const char *mnem, MachInst _machInst, OpClass __opClass) + : PCDependentDisassembly(mnem, _machInst, __opClass), + disp(OFFSET << 2) + { + //If Bit 17 is 1 then Sign Extend + if ( (disp & 0x00020000) > 0 ) { + disp |= 0xFFFE0000; + } + } + + Addr branchTarget(Addr branchPC) const; + + std::string + generateDisassembly(Addr pc, const SymbolTable *symtab) const; + }; + + /** + * Base class for jumps (register-indirect control transfers). In + * the Mips ISA, these are always unconditional. + */ + class Jump : public PCDependentDisassembly + { + protected: + + /// Displacement to target address (signed). + int32_t disp; + + uint32_t target; + + public: + /// Constructor + Jump(const char *mnem, MachInst _machInst, OpClass __opClass) + : PCDependentDisassembly(mnem, _machInst, __opClass), + disp(JMPTARG << 2) + { + } + + Addr branchTarget(ThreadContext *tc) 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(ThreadContext *tc) const + { + Addr NPC = tc->readPC() + 4; + uint64_t Rb = tc->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 == 1) { + printReg(ss, _srcRegIdx[0]); + ss << ", "; + } else if(_numSrcRegs == 2) { + printReg(ss, _srcRegIdx[0]); + ss << ", "; + printReg(ss, _srcRegIdx[1]); + ss << ", "; + } + + 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); + + if ( mnemonic == "jal" ) { + Addr npc = pc + 4; + ccprintf(ss,"0x%x",(npc & 0xF0000000) | disp); + } else if (_numSrcRegs == 0) { + std::string str; + if (symtab && symtab->findSymbol(disp, str)) + ss << str; + else + ccprintf(ss, "0x%x", disp); + } else if (_numSrcRegs == 1) { + printReg(ss, _srcRegIdx[0]); + } else if(_numSrcRegs == 2) { + printReg(ss, _srcRegIdx[0]); + ss << ", "; + printReg(ss, _srcRegIdx[1]); + } + + return ss.str(); + } +}}; + +def format Branch(code,*opt_flags) {{ + not_taken_code = ' NNPC = NNPC;\n' + not_taken_code += '} \n' + + #Build Instruction Flags + #Use Link & Likely Flags to Add Link/Condition Code + inst_flags = ('IsDirectControl', ) + for x in opt_flags: + if x == 'Link': + code += 'R31 = NNPC;\n' + elif x == 'Likely': + not_taken_code = ' NPC = NNPC;\n' + not_taken_code += ' NNPC = NNPC + 4;\n' + not_taken_code += '} \n' + inst_flags = ('IsCondDelaySlot', ) + else: + inst_flags += (x, ) + + if 'cond == 1' in code: + inst_flags += ('IsCondControl', ) + else: + inst_flags += ('IsUncondControl', ) + + #Condition code + code = 'bool cond;\n' + code + code += 'if (cond) {\n' + code += ' NNPC = NPC + disp;\n' + code += '} else {\n' + code += not_taken_code + + iop = InstObjParams(name, Name, 'Branch', CodeBlock(code), inst_flags) + header_output = BasicDeclare.subst(iop) + decoder_output = BasicConstructor.subst(iop) + decode_block = BasicDecode.subst(iop) + exec_output = BasicExecute.subst(iop) +}}; + +def format Jump(code, *opt_flags) {{ + #Build Instruction Flags + #Use Link Flag to Add Link Code + inst_flags = ('IsIndirectControl', 'IsUncondControl') + for x in opt_flags: + if x == 'Link': + code = 'R31 = NNPC;\n' + code + elif x == 'ClearHazards': + code += '/* Code Needed to Clear Execute & Inst Hazards */\n' + else: + inst_flags += (x, ) + + iop = InstObjParams(name, Name, 'Jump', CodeBlock(code), inst_flags) + header_output = BasicDeclare.subst(iop) + decoder_output = BasicConstructor.subst(iop) + decode_block = BasicDecode.subst(iop) + exec_output = BasicExecute.subst(iop) +}}; + + + + |