Re: [Libjit] Basic float32 issue

[Aleksey Demakov]

Hi Matt,

Thanks for the report. I will take a look into it in the next few days.

Regards,
Aleksey

On Sun, Apr 17, 2016 at 7:52 AM, Matthew Keeter <address@hidden> wrote:
> Digging a little deeper, the IR looks fine but the generated assembly is
> missing a data / bss section with float constants:
>
> Before compiling:
> function test() : float32
> .L:
>         return_float32(19.000000)
>         ends_in_dead
> .L:
> .L:
> end
>
> After compiling:
> function test() : float32
>
> /tmp/libjit-dump.o:     file format mach-o-x86-64
>
>
> Disassembly of section .text:
>
> 000000010413914c <.text>:
>    10413914c:   55                      push   %rbp
>    10413914d:   48 8b ec                mov    %rsp,%rbp
>    104139150:   f3 0f 10 05 78 fe 00    movss  0xfe78(%rip),%xmm0        #
> 0x104148fd0
>    104139157:   00
>    104139158:   48 8b e5                mov    %rbp,%rsp
>    10413915b:   5d                      pop    %rbp
>    10413915c:   c3                      retq
>
> end
>
> In particular, note that
>     movss  0xfe78(%rip),%xmm0        # 0x104148fd0
> is pointing off into space.
>
> Does this ring any bells?
>
> Thanks,
> Matt
>
> On Apr 16, 2016, at 9:09 PM, Matthew Keeter <address@hidden> wrote:
>
> Hi all,
>
> I’m having trouble with floating-point operations and have reduced to a very
> simple test case.
> The code below creates a function with no arguments that just returns a
> float32 constant.
>
> For some reason, instead of returning the constant’s value, it always gives
> zero.
>
> Identical code with jit_type_int works fine, so I’m puzzled as to what’s
> going on.
> Any ideas?  The code is pasted below
>
> Thanks,
> Matt
>
> {
>    jit_context_t context;
>    jit_type_t signature;
>    jit_function_t function;
>    jit_value_t c;
>    jit_float32 result;
>
>    context = jit_context_create();
>    jit_context_build_start(context);
>
>    signature = jit_type_create_signature
>        (jit_abi_cdecl, jit_type_float32, NULL, 0, 1);
>
>    function = jit_function_create(context, signature);
>
>    c = jit_value_create_float32_constant(function, jit_type_float32,
> (jit_float32)13.0f);
>    jit_insn_return(function, c);
>
>    jit_function_compile(function);
>    jit_context_build_end(context);
>    jit_function_apply(function, NULL, &result);
>    printf("const(13) = %f\n", (float)result);
>
>    jit_context_destroy(context);
> }
>
>