Hello,
Thanks for the explanation; I can see the issue now.
Ryan
> On Apr 11, 2020, at 9:16 PM, Xi Ruoyao <xry111@xxxxxxxxxxxxxxxx> wrote:
>
> On 2020-04-11 16:31 -0500, relliott--- via Gcc-help wrote:
>> Hello,
>>
>> Thanks for your reply. I guess I don’t understand why this requires so much
>> memory all at once. Is it not possible to write to the object file as the
>> initializer is parsed?
>
> A compiler doesn't write to object file. It only writes to assembly file.
> Modern compilers are designed multi-layer so the parser (frontend) should not
> output assembly (it's the job of the backend). And, doing that so will miss
> optimizations. A simple code:
>
> const int b[] = {0, 1, 2};
>
> int foo(void)
> {
> int i, x = 0;
> for (i = 0; i < 3; i++)
> x += b[i];
> return x;
> }
>
> The body of "foo" will be optimized to "return 3;" at -O2. If we wrote the
> array content to assembly file and discarded the value in memory, this
> optimization will be impossible.
>
> "xxd" a binary file and then compile the result with a compiler is just like
> "converting a .jpg to .png then back to .jpg". A smarter way:
>
> ld -r -b binary some_big_binary_blob.bin -o some_big_binary_blob.o
>
> There will be symbols _binary_some_big_binary_blob_bin_start,
> _binary_some_big_binary_blob_end in some_big_binary_blob.o. Then it's possible
> to access the content of the binary blob with:
>
> extern const char _binary_some_big_binary_blob_bin_start;
> extern const char _binary_some_big_binary_blob_bin_end;
>
> int main(void)
> {
> const char *begin = &_binary_some_big_binary_blob_bin_start;
> const char *end = &_binary_some_big_binary_blob_bin_end;
> const char *p;
> for (p = begin; p != end; p++)
> play_with(*p);
> }
> --
> Xi Ruoyao <xry111@xxxxxxxxxxxxxxxx>
> School of Aerospace Science and Technology, Xidian University
>
