我将遇到的问题简化为一个小示例。这是我使用的LLVM汇编器代码(在foo.ll中):
target datalayout = "e-p:64:64:64-S128-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f16:16:16-f32:32:32-f64:64:64-f128:128:128-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-pc-linux-gnu"
define fastcc i32 @foo(i32) {
entry:
%x = add i32 %0, 1
ret i32 %x
}
define i32 @main(i32, i8**) {
entry:
%2 = call i32 @foo(i32 %0)
ret i32 %2
}
然后我使用以下命令进行编译:
clang -O1 -o foo foo.ll
...当我运行它时,会得到以下结果:
Illegal instruction (core dumped)
...所以我启动了调试器,然后看到了这个:
Program received signal SIGILL, Illegal instruction.
0x00000000004004d0 in main ()
(gdb) bt
#0 0x00000000004004d0 in main ()
(gdb) disas
Dump of assembler code for function main:
=> 0x00000000004004d0 <+0>: ud2
End of assembler dump.
(gdb)
请注意,如果更改以下任一项,则程序将正常执行:
- 从clang标志中删除-O1
- 在foo.ll中声明@foo时删除fastcc
clang version 3.3 (tags/RELEASE_33/final)
Target: x86_64-unknown-linux-gnu
Thread model: posix
另外,如果有帮助的话,这里是"objdump -d foo"的结果。