From: Gabe Black Date: Wed, 13 Dec 2017 01:54:58 +0000 (-0800) Subject: x86: Rework how "split" loads/stores are handled. X-Git-Tag: v19.0.0.0~2435 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=36d5e8925526b15d1638ac44380e4ada5af16e08;p=gem5.git x86: Rework how "split" loads/stores are handled. Explicitly separate the way the data is represented in the underlying representation from how it's represented in the instruction. In order to make the ISA parser happy, the Mem operand needs to have a single, particular type. To handle that with scalar types, we just used uint64_ts and then worked with values that were smaller than the maximum we could hold. To work with these new array values, we also use an underlying uint64_t for each element. To make accessing the underlying memory system more natural, when we go to actually read or write values, we translate the access into an array of the actual, correct underlying type. That way we don't have non-exact asserts which confuse gcc, or weird endianness conversion which assumes that the data should be flipped 8 bytes at a time. Because the functions involved are generally inline, the syntactic niceness should all boil off, and the final implementation in the binary should be simple and efficient for the given data types. Change-Id: I14ce7a2fe0dc2cbaf6ad4a0d19f743c45ee78e26 Reviewed-on: https://gem5-review.googlesource.com/6582 Reviewed-by: Gabe Black Maintainer: Gabe Black --- diff --git a/src/arch/x86/isa/microops/ldstop.isa b/src/arch/x86/isa/microops/ldstop.isa index 5ff4f0cea..a3d9c5a70 100644 --- a/src/arch/x86/isa/microops/ldstop.isa +++ b/src/arch/x86/isa/microops/ldstop.isa @@ -99,8 +99,7 @@ def template MicroLoadExecute {{ %(ea_code)s; DPRINTF(X86, "%s : %s: The address is %#x\n", instMnem, mnemonic, EA); - fault = readMemAtomic(xc, traceData, EA, Mem, - %(memDataSize)s, memFlags); + fault = readMemAtomic(xc, traceData, EA, Mem, dataSize, memFlags); if (fault == NoFault) { %(code)s; @@ -145,7 +144,7 @@ def template MicroLoadCompleteAcc {{ %(op_decl)s; %(op_rd)s; - getMem(pkt, Mem, %(memDataSize)s, traceData); + getMem(pkt, Mem, dataSize, traceData); %(code)s; @@ -174,12 +173,10 @@ def template MicroStoreExecute {{ %(code)s; - if(fault == NoFault) - { - fault = writeMemAtomic(xc, traceData, Mem, %(memDataSize)s, EA, - memFlags, NULL); - if(fault == NoFault) - { + if (fault == NoFault) { + fault = writeMemAtomic(xc, traceData, Mem, dataSize, EA, + memFlags, NULL); + if (fault == NoFault) { %(op_wb)s; } } @@ -202,10 +199,9 @@ def template MicroStoreInitiateAcc {{ %(code)s; - if(fault == NoFault) - { - fault = writeMemTiming(xc, traceData, Mem, %(memDataSize)s, EA, - memFlags, NULL); + if (fault == NoFault) { + fault = writeMemTiming(xc, traceData, Mem, dataSize, EA, + memFlags, NULL); } return fault; } @@ -561,18 +557,9 @@ let {{ microopClasses[name] = LoadOp code = ''' - switch (dataSize) { - case 4: - DataLow = bits(Mem_u2qw[0], 31, 0); - DataHi = bits(Mem_u2qw[0], 63, 32); - break; - case 8: - DataLow = Mem_u2qw[0]; - DataHi = Mem_u2qw[1]; - break; - default: - panic("Unhandled data size %d in LdSplit.\\n", dataSize); - }''' + DataLow = Mem_u2qw[0]; + DataHi = Mem_u2qw[1]; + ''' defineMicroLoadSplitOp('LdSplit', code, '(StoreCheck << FlagShift)') @@ -683,17 +670,9 @@ let {{ microopClasses[name] = StoreOp code = ''' - switch (dataSize) { - case 4: - Mem_u2qw[0] = (DataHi << 32) | DataLow; - break; - case 8: - Mem_u2qw[0] = DataLow; - Mem_u2qw[1] = DataHi; - break; - default: - panic("Unhandled data size %d in StSplit.\\n", dataSize); - }''' + Mem_u2qw[0] = DataLow; + Mem_u2qw[1] = DataHi; + ''' defineMicroStoreSplitOp('StSplit', code); diff --git a/src/arch/x86/memhelpers.hh b/src/arch/x86/memhelpers.hh index 00a6e9a33..aa3617b43 100644 --- a/src/arch/x86/memhelpers.hh +++ b/src/arch/x86/memhelpers.hh @@ -74,24 +74,30 @@ getMem(PacketPtr pkt, uint64_t &mem, unsigned dataSize, traceData->setData(mem); } +template +static void +getPackedMem(PacketPtr pkt, std::array &mem, unsigned dataSize) +{ + std::array real_mem = pkt->get >(); + for (int i = 0; i < N; i++) + mem[i] = real_mem[i]; +} template -void +static void getMem(PacketPtr pkt, std::array &mem, unsigned dataSize, Trace::InstRecord *traceData) { - assert(dataSize >= 8); - assert((dataSize % 8) == 0); - - int num_words = dataSize / 8; - assert(num_words <= N); - - auto pkt_data = pkt->getConstPtr(); - for (int i = 0; i < num_words; ++i) - mem[i] = gtoh(pkt_data[i]); - - // traceData record only has space for 64 bits, so we just record - // the first qword + switch (dataSize) { + case 4: + getPackedMem(pkt, mem, dataSize); + break; + case 8: + getPackedMem(pkt, mem, dataSize); + break; + default: + panic("Unhandled element size in getMem.\n"); + } if (traceData) traceData->setData(mem[0]); } @@ -114,62 +120,86 @@ readMemAtomic(ExecContext *xc, Trace::InstRecord *traceData, Addr addr, return fault; } +template +static Fault +readPackedMemAtomic(ExecContext *xc, Addr addr, std::array &mem, + unsigned flags) +{ + std::array real_mem; + Fault fault = xc->readMem(addr, (uint8_t *)&real_mem, + sizeof(T) * N, flags); + if (fault == NoFault) { + real_mem = gtoh(real_mem); + for (int i = 0; i < N; i++) + mem[i] = real_mem[i]; + } + return fault; +} + template -Fault +static Fault readMemAtomic(ExecContext *xc, Trace::InstRecord *traceData, Addr addr, std::array &mem, unsigned dataSize, unsigned flags) { - assert(dataSize >= 8); - assert((dataSize % 8) == 0); - - Fault fault = xc->readMem(addr, (uint8_t *)&mem, dataSize, flags); - - if (fault == NoFault) { - int num_words = dataSize / 8; - assert(num_words <= N); - - for (int i = 0; i < num_words; ++i) - mem[i] = gtoh(mem[i]); + Fault fault = NoFault; - if (traceData) - traceData->setData(mem[0]); + switch (dataSize) { + case 4: + fault = readPackedMemAtomic(xc, addr, mem, flags); + break; + case 8: + fault = readPackedMemAtomic(xc, addr, mem, flags); + break; + default: + panic("Unhandled element size in readMemAtomic\n"); } + if (fault == NoFault && traceData) + traceData->setData(mem[0]); return fault; } +template +static Fault +writePackedMem(ExecContext *xc, std::array &mem, Addr addr, + unsigned flags, uint64_t *res) +{ + std::array real_mem; + for (int i = 0; i < N; i++) + real_mem[i] = mem[i]; + real_mem = htog(real_mem); + return xc->writeMem((uint8_t *)&real_mem, sizeof(T) * N, + addr, flags, res); +} + static Fault writeMemTiming(ExecContext *xc, Trace::InstRecord *traceData, uint64_t mem, unsigned dataSize, Addr addr, Request::Flags flags, uint64_t *res) { - if (traceData) { + if (traceData) traceData->setData(mem); - } mem = TheISA::htog(mem); return xc->writeMem((uint8_t *)&mem, dataSize, addr, flags, res); } template -Fault +static Fault writeMemTiming(ExecContext *xc, Trace::InstRecord *traceData, std::array &mem, unsigned dataSize, Addr addr, unsigned flags, uint64_t *res) { - assert(dataSize >= 8); - assert((dataSize % 8) == 0); - - if (traceData) { + if (traceData) traceData->setData(mem[0]); - } - - int num_words = dataSize / 8; - assert(num_words <= N); - for (int i = 0; i < num_words; ++i) - mem[i] = htog(mem[i]); - - return xc->writeMem((uint8_t *)&mem, dataSize, addr, flags, res); + switch (dataSize) { + case 4: + return writePackedMem(xc, mem, addr, flags, res); + case 8: + return writePackedMem(xc, mem, addr, flags, res); + default: + panic("Unhandled element size in writeMemTiming.\n"); + } } static Fault @@ -177,39 +207,39 @@ writeMemAtomic(ExecContext *xc, Trace::InstRecord *traceData, uint64_t mem, unsigned dataSize, Addr addr, Request::Flags flags, uint64_t *res) { - if (traceData) { + if (traceData) traceData->setData(mem); - } uint64_t host_mem = TheISA::htog(mem); Fault fault = xc->writeMem((uint8_t *)&host_mem, dataSize, addr, flags, res); - if (fault == NoFault && res != NULL) { + if (fault == NoFault && res) *res = gtoh(*res); - } return fault; } template -Fault +static Fault writeMemAtomic(ExecContext *xc, Trace::InstRecord *traceData, std::array &mem, unsigned dataSize, Addr addr, unsigned flags, uint64_t *res) { - if (traceData) { + if (traceData) traceData->setData(mem[0]); - } - - int num_words = dataSize / 8; - assert(num_words <= N); - - for (int i = 0; i < num_words; ++i) - mem[i] = htog(mem[i]); - Fault fault = xc->writeMem((uint8_t *)&mem, dataSize, addr, flags, res); + Fault fault; + switch (dataSize) { + case 4: + fault = writePackedMem(xc, mem, addr, flags, res); + break; + case 8: + fault = writePackedMem(xc, mem, addr, flags, res); + break; + default: + panic("Unhandled element size in writeMemAtomic.\n"); + } - if (fault == NoFault && res != NULL) { + if (fault == NoFault && res) *res = gtoh(*res); - } return fault; }