[llvm] r301653 - [bpf] add bigendian support to disassembler
Alexei Starovoitov via llvm-commits
llvm-commits at lists.llvm.org
Fri Apr 28 10:16:49 PDT 2017
I've considered them, but since it's 8-byte insn with different fields
in host endianness,
it's easier to understand when it's all explicit.
On Fri, Apr 28, 2017 at 10:12 AM, Rui Ueyama <ruiu at google.com> wrote:
> llvm/include/llvm/Support/Endian.h provides read32le and read32be to read
> 32-bit little or big-endian integers. Doesn't it work for you?
>
> On Fri, Apr 28, 2017 at 9:51 AM, Alexei Starovoitov via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>>
>> Author: ast
>> Date: Fri Apr 28 11:51:01 2017
>> New Revision: 301653
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=301653&view=rev
>> Log:
>> [bpf] add bigendian support to disassembler
>>
>> . swap 4-bit register encoding, 16-bit offset and 32-bit imm to support
>> big endian archs
>> . add a test
>>
>> Reported-by: David S. Miller <davem at davemloft.net>
>> Signed-off-by: Alexei Starovoitov <ast at kernel.org>
>>
>> Added:
>> llvm/trunk/test/CodeGen/BPF/mem_offset_be.ll
>> Modified:
>> llvm/trunk/lib/Target/BPF/Disassembler/BPFDisassembler.cpp
>>
>> Modified: llvm/trunk/lib/Target/BPF/Disassembler/BPFDisassembler.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/BPF/Disassembler/BPFDisassembler.cpp?rev=301653&r1=301652&r2=301653&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Target/BPF/Disassembler/BPFDisassembler.cpp (original)
>> +++ llvm/trunk/lib/Target/BPF/Disassembler/BPFDisassembler.cpp Fri Apr 28
>> 11:51:01 2017
>> @@ -17,6 +17,8 @@
>> #include "llvm/ADT/ArrayRef.h"
>> #include "llvm/MC/MCDisassembler/MCDisassembler.h"
>> #include "llvm/MC/MCFixedLenDisassembler.h"
>> +#include "llvm/MC/MCContext.h"
>> +#include "llvm/MC/MCAsmInfo.h"
>> #include "llvm/MC/MCInst.h"
>> #include "llvm/Support/MathExtras.h"
>> #include "llvm/Support/TargetRegistry.h"
>> @@ -88,9 +90,9 @@ static DecodeStatus decodeMemoryOpValue(
>> }
>>
>> #include "BPFGenDisassemblerTables.inc"
>> -
>> static DecodeStatus readInstruction64(ArrayRef<uint8_t> Bytes, uint64_t
>> Address,
>> - uint64_t &Size, uint64_t &Insn) {
>> + uint64_t &Size, uint64_t &Insn,
>> + bool IsLittleEndian) {
>> uint64_t Lo, Hi;
>>
>> if (Bytes.size() < 8) {
>> @@ -99,8 +101,14 @@ static DecodeStatus readInstruction64(Ar
>> }
>>
>> Size = 8;
>> - Hi = (Bytes[0] << 24) | (Bytes[1] << 16) | (Bytes[2] << 0) | (Bytes[3]
>> << 8);
>> - Lo = (Bytes[4] << 0) | (Bytes[5] << 8) | (Bytes[6] << 16) | (Bytes[7]
>> << 24);
>> + if (IsLittleEndian) {
>> + Hi = (Bytes[0] << 24) | (Bytes[1] << 16) | (Bytes[2] << 0) |
>> (Bytes[3] << 8);
>> + Lo = (Bytes[4] << 0) | (Bytes[5] << 8) | (Bytes[6] << 16) | (Bytes[7]
>> << 24);
>> + } else {
>> + Hi = (Bytes[0] << 24) | ((Bytes[1] & 0x0F) << 20) | ((Bytes[1] &
>> 0xF0) << 12) |
>> + (Bytes[2] << 8) | (Bytes[3] << 0);
>> + Lo = (Bytes[4] << 24) | (Bytes[5] << 16) | (Bytes[6] << 8) |
>> (Bytes[7] << 0);
>> + }
>> Insn = Make_64(Hi, Lo);
>>
>> return MCDisassembler::Success;
>> @@ -111,10 +119,11 @@ DecodeStatus BPFDisassembler::getInstruc
>> uint64_t Address,
>> raw_ostream &VStream,
>> raw_ostream &CStream) const
>> {
>> - uint64_t Insn;
>> + bool IsLittleEndian = getContext().getAsmInfo()->isLittleEndian();
>> + uint64_t Insn, Hi;
>> DecodeStatus Result;
>>
>> - Result = readInstruction64(Bytes, Address, Size, Insn);
>> + Result = readInstruction64(Bytes, Address, Size, Insn, IsLittleEndian);
>> if (Result == MCDisassembler::Fail) return MCDisassembler::Fail;
>>
>> Result = decodeInstruction(DecoderTableBPF64, Instr, Insn,
>> @@ -128,7 +137,10 @@ DecodeStatus BPFDisassembler::getInstruc
>> return MCDisassembler::Fail;
>> }
>> Size = 16;
>> - uint64_t Hi = (Bytes[12] << 0) | (Bytes[13] << 8) | (Bytes[14] << 16)
>> | (Bytes[15] << 24);
>> + if (IsLittleEndian)
>> + Hi = (Bytes[12] << 0) | (Bytes[13] << 8) | (Bytes[14] << 16) |
>> (Bytes[15] << 24);
>> + else
>> + Hi = (Bytes[12] << 24) | (Bytes[13] << 16) | (Bytes[14] << 8) |
>> (Bytes[15] << 0);
>> auto& Op = Instr.getOperand(1);
>> Op.setImm(Make_64(Hi, Op.getImm()));
>> break;
>>
>> Added: llvm/trunk/test/CodeGen/BPF/mem_offset_be.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/BPF/mem_offset_be.ll?rev=301653&view=auto
>>
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/BPF/mem_offset_be.ll (added)
>> +++ llvm/trunk/test/CodeGen/BPF/mem_offset_be.ll Fri Apr 28 11:51:01 2017
>> @@ -0,0 +1,18 @@
>> +; RUN: llc -march=bpfeb -show-mc-encoding < %s | FileCheck %s
>> +
>> +; Function Attrs: nounwind
>> +define i32 @bpf_prog1(i8* nocapture readnone) local_unnamed_addr #0 {
>> +; CHECK: r1 = 590618314553ll # encoding:
>> [0x18,0x10,0x00,0x00,0x83,0x98,0x47,0x39,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x89]
>> +; CHECK: r1 += -1879113726 # encoding:
>> [0x07,0x10,0x00,0x00,0x8f,0xff,0x00,0x02]
>> +; CHECK: r0 = *(u64 *)(r1 + 0) # encoding:
>> [0x79,0x01,0x00,0x00,0x00,0x00,0x00,0x00]
>> + %2 = alloca i64, align 8
>> + %3 = bitcast i64* %2 to i8*
>> + store volatile i64 590618314553, i64* %2, align 8
>> + %4 = load volatile i64, i64* %2, align 8
>> + %5 = add i64 %4, -1879113726
>> + %6 = inttoptr i64 %5 to i64*
>> + %7 = load i64, i64* %6, align 8
>> + %8 = trunc i64 %7 to i32
>> + ret i32 %8
>> +}
>> +
>>
>>
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