| Issue |
146451
|
| Summary |
[AVR] llvm-objdump should automatically select the instruction set
|
| Labels |
new issue
|
| Assignees |
benshi001
|
| Reporter |
benshi001
|
Given a simple test program:
```c++
int adiw(int a) {
return a + 51;
}
```
Build it with `clang a.c --target=avr -mmcu=avr2 -c -O3`, and then disassemble it with `llvm-objdump -d a.o`, we see
```asm
a.o: file format elf32-avr
Disassembly of section .text:
00000000 <adiw>:
0: c3 96 08 95 <unknown>
```
We must specify `--mcpu=avr2` to `llvm-objdump` explicitly to make `adiw` correctly decoded.
```asm
a.o: file format elf32-avr
Disassembly of section .text:
00000000 <adiw>:
0: c3 96 adiw r24, 0x33
2: 08 95 ret
```
However the generated object file does contain the `avr2` family information.
```bash
ELF Header:
Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: REL (Relocatable file)
Machine: Atmel AVR 8-bit microcontroller
Version: 0x1
Entry point address: 0x0
Start of program headers: 0 (bytes into file)
Start of section headers: 284 (bytes into file)
Flags: 0x82, EF_AVR_ARCH_AVR2, relaxable
Size of this header: 52 (bytes)
Size of program headers: 0 (bytes)
Number of program headers: 0
Size of section headers: 40 (bytes)
Number of section headers: 5
Section header string table index: 1
```
So the `llvm-objdump` should automatically select the avr family according to ELF header, other than rely on user's explicit specification.
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