[LLDB][LoongArch] Add LoongArch ArchSpec and subtype detection

[seehearfeel]

Summary

Define LoongArch architecture subtypes, add the LoongArch ArchSpec bits,
and inspect the ELF header to detect the right subtype based on ELF class.

Here is a simple test:

[loongson@linux ~]$ cat hello.c 
#include <stdio.h>

int main()
{
	printf("Hello, World!\n");
	return 0;
}
[loongson@linux ~]$ clang hello.c -g -o hello

Without this patch:

[loongson@linux ~]$ llvm-project/llvm/build/bin/lldb hello
(lldb) target create "hello"
error: '/home/loongson/hello' doesn't contain any 'host' platform architectures: unknown

With this patch:

[loongson@linux ~]$ llvm-project/llvm/build/bin/lldb hello
(lldb) target create "hello"
Current executable set to '/home/loongson/hello' (loongarch64).
(lldb) run
Process 735167 launched: '/home/loongson/hello' (loongarch64)
Hello, World!
Process 735167 exited with status = 0 (0x00000000) 
(lldb) quit
[loongson@linux ~]$ llvm-project/llvm/build/bin/llvm-lit llvm-project/lldb/test/Shell/ObjectFile/ELF/loongarch-arch.yaml
llvm-lit: /home/loongson/llvm-project/llvm/utils/lit/lit/llvm/config.py:456: note: using clang: /home/loongson/llvm-project/llvm/build/bin/clang
-- Testing: 1 tests, 1 workers --
PASS: lldb-shell :: ObjectFile/ELF/loongarch-arch.yaml (1 of 1)

Testing Time: 0.09s
  Passed: 1

[DavidSpickett]

Looks good to me.

[xen0n]

lldb/include/lldb/Utility/ArchSpec.h

111

Should be LoongArch. It's that way everywhere else in LLVM land.

lldb/source/Utility/ArchSpec.cpp

223

min_opcode_byte_size should be 4 too, all LoongArch insns are 32 bits long. Same for loongarch64.

[SixWeining]

lldb/source/Utility/ArchSpec.cpp

223

Right. So, the test doesn't cover this change?

[seehearfeel]

lldb/source/Utility/ArchSpec.cpp

223

OK, thank you.

It is a bit confusing at the first glance.
Maybe "min_opcode_byte_size" should rename to "min_insn_byte_size",
and "max_opcode_byte_size" should rename to "max_insn_byte_size".

[seehearfeel]

In D137057#3895926, @DavidSpickett wrote:

Looks good to me.

Thanks for your review.

Let me update the diff to do some small modifications.

[seehearfeel]

(1) Rename LOONGARCHSubType to LoongArchSubType
(2) Define min_opcode_byte_size as 4 for LoongArch

lldb/include/lldb/Utility/ArchSpec.h

public:
   };
 
   enum RISCVSubType {
     eRISCVSubType_unknown,
     eRISCVSubType_riscv32,
     eRISCVSubType_riscv64,
   };
 
+  enum LoongArchSubType {
+    eLoongArchSubType_unknown,
+    eLoongArchSubType_loongarch32,
+    eLoongArchSubType_loongarch64,
+  };
+
   enum Core {
     eCore_arm_generic,
     eCore_arm_armv4,
     eCore_arm_armv4t,
     eCore_arm_armv5,
     eCore_arm_armv5e,
     eCore_arm_armv5t,
     eCore_arm_armv6,
enum Core {
     eCore_x86_64_x86_64h, // Haswell enabled x86_64
     eCore_hexagon_generic,
     eCore_hexagon_hexagonv4,
     eCore_hexagon_hexagonv5,
 
     eCore_riscv32,
     eCore_riscv64,
 
+    eCore_loongarch32,
+    eCore_loongarch64,
+
     eCore_uknownMach32,
     eCore_uknownMach64,
 
     eCore_arc, // little endian ARC
 
     eCore_avr,
 
     eCore_wasm32,

lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

 static uint32_t ppc64VariantFromElfFlags(const elf::ELFHeader &header) {
   uint32_t endian = header.e_ident[EI_DATA];
   if (endian == ELFDATA2LSB)
     return ArchSpec::eCore_ppc64le_generic;
   else
     return ArchSpec::eCore_ppc64_generic;
 }
 
+static uint32_t loongarchVariantFromElfFlags(const elf::ELFHeader &header) {
+  uint32_t fileclass = header.e_ident[EI_CLASS];
+  switch (fileclass) {
+  case llvm::ELF::ELFCLASS32:
+    return ArchSpec::eLoongArchSubType_loongarch32;
+  case llvm::ELF::ELFCLASS64:
+    return ArchSpec::eLoongArchSubType_loongarch64;
+  default:
+    return ArchSpec::eLoongArchSubType_unknown;
+  }
+}
+
 static uint32_t subTypeFromElfHeader(const elf::ELFHeader &header) {
   if (header.e_machine == llvm::ELF::EM_MIPS)
     return mipsVariantFromElfFlags(header);
   else if (header.e_machine == llvm::ELF::EM_PPC64)
     return ppc64VariantFromElfFlags(header);
   else if (header.e_machine == llvm::ELF::EM_RISCV)
     return riscvVariantFromElfFlags(header);
+  else if (header.e_machine == llvm::ELF::EM_LOONGARCH)
+    return loongarchVariantFromElfFlags(header);
 
   return LLDB_INVALID_CPUTYPE;
 }
 
 char ObjectFileELF::ID;
 
 // Arbitrary constant used as UUID prefix for core files.
 const uint32_t ObjectFileELF::g_core_uuid_magic(0xE210C);

lldb/source/Utility/ArchSpec.cpp

static const CoreDefinition g_core_definitions[] = {
     {eByteOrderLittle, 4, 4, 4, llvm::Triple::hexagon,
      ArchSpec::eCore_hexagon_hexagonv5, "hexagonv5"},
 
     {eByteOrderLittle, 4, 2, 4, llvm::Triple::riscv32, ArchSpec::eCore_riscv32,
      "riscv32"},
     {eByteOrderLittle, 8, 2, 4, llvm::Triple::riscv64, ArchSpec::eCore_riscv64,
      "riscv64"},
 
+    {eByteOrderLittle, 4, 4, 4, llvm::Triple::loongarch32,
+     ArchSpec::eCore_loongarch32, "loongarch32"},
+    {eByteOrderLittle, 8, 4, 4, llvm::Triple::loongarch64,
+     ArchSpec::eCore_loongarch64, "loongarch64"},
+
     {eByteOrderLittle, 4, 4, 4, llvm::Triple::UnknownArch,
      ArchSpec::eCore_uknownMach32, "unknown-mach-32"},
     {eByteOrderLittle, 8, 4, 4, llvm::Triple::UnknownArch,
      ArchSpec::eCore_uknownMach64, "unknown-mach-64"},
     {eByteOrderLittle, 4, 2, 4, llvm::Triple::arc, ArchSpec::eCore_arc, "arc"},
 
     {eByteOrderLittle, 2, 2, 4, llvm::Triple::avr, ArchSpec::eCore_avr, "avr"},
 
static const ArchDefinitionEntry g_elf_arch_entries[] = {
     {ArchSpec::eCore_arc, llvm::ELF::EM_ARC_COMPACT2, LLDB_INVALID_CPUTYPE,
      0xFFFFFFFFu, 0xFFFFFFFFu}, // ARC
     {ArchSpec::eCore_avr, llvm::ELF::EM_AVR, LLDB_INVALID_CPUTYPE, 0xFFFFFFFFu,
      0xFFFFFFFFu}, // AVR
     {ArchSpec::eCore_riscv32, llvm::ELF::EM_RISCV,
      ArchSpec::eRISCVSubType_riscv32, 0xFFFFFFFFu, 0xFFFFFFFFu}, // riscv32
     {ArchSpec::eCore_riscv64, llvm::ELF::EM_RISCV,
      ArchSpec::eRISCVSubType_riscv64, 0xFFFFFFFFu, 0xFFFFFFFFu}, // riscv64
+    {ArchSpec::eCore_loongarch32, llvm::ELF::EM_LOONGARCH,
+     ArchSpec::eLoongArchSubType_loongarch32, 0xFFFFFFFFu,
+     0xFFFFFFFFu}, // loongarch32
+    {ArchSpec::eCore_loongarch64, llvm::ELF::EM_LOONGARCH,
+     ArchSpec::eLoongArchSubType_loongarch64, 0xFFFFFFFFu,
+     0xFFFFFFFFu}, // loongarch64
 };
 
 static const ArchDefinition g_elf_arch_def = {
     eArchTypeELF,
     std::size(g_elf_arch_entries),
     g_elf_arch_entries,
     "elf",
 };

lldb/test/Shell/ObjectFile/ELF/loongarch-arch.yaml

+# RUN: yaml2obj --docnum=1 %s > %t32
+# RUN: yaml2obj --docnum=2 %s > %t64
+# RUN: lldb-test object-file %t32 | FileCheck --check-prefix=CHECK-LA32 %s
+# RUN: lldb-test object-file %t64 | FileCheck --check-prefix=CHECK-LA64 %s
+
+# CHECK-LA32: Architecture: loongarch32--
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS32
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_LOONGARCH
+...
+
+# CHECK-LA64: Architecture: loongarch64--
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_LOONGARCH
+...