Constant offset of address failing to parse with inline assembly

[negge]

When adding a constant offset to an address using inline assembly, some expressions fail to parse. Consider the example:

float nums[3*4 + 2];

static void test_store_at_offset(float a);
#pragma aux test_store_at_offset parm [ 8087 ] = \
  "mov esi, offset nums + 3*4*4" \
  "fstp dword ptr [esi]"

void main() {
  test_store_at_offset(0);
}

Compiling gives this error:

$ wcc386 -q -s test3.c
test3.c(5): Error! E1156: Assembler error: 'A constant operand is expected in multiplication'

However changing the expression to 3*16 works fine. So do more complex expressions like (3*4 + 1)*4.

[jmalak]

Thanks for bug report. I will review.

[jmalak]

Take into account that in-line assembler is simple without functionality of standalone assembler. It use simple expression evaluator. It is supposed that complex expression will be resolved by C front end and in-line assembler do only basic operation.

Your code should looks like

float nums[3*4 + 2];

static void test_store_at_offset(float a, float *b);
#pragma aux test_store_at_offset parm [ 8087 ] [esi] = \
  "fstp dword ptr [esi]"

void main() {
  test_store_at_offset(0, nums + 3*4);
}

which is compiled as

main_:
        push            esi
        fldz
        mov             esi,offset FLAT:_nums+30H
        fstp            dword ptr [esi]
        pop             esi
        ret

Anyway I will look on this problem with expression evaluation.