Re: [PATCH 1/2] Do not overflow M1 immediates.

[Janneke Nieuwenhuizen]

Andrius tikonas via Bug reports for GNU Mes writes:

Hi!

As discussed on IRC, this patch works nicely, also on x86_64, I've made
some minor changes, see below.

> M1 immediates are limited to 31-bit before they become negative.
>
> * module/mescc/x86_64/as.scm: limit M1 immediates to #x80000000.
> * lib/tests/scaffold/67-m1-overflow-check.c: add a new test.

I've slightly modified the changelog to this

--8<---------------cut here---------------start------------->8---
mescc: Do not overflow M1 64bit immediates.

M1 immediates are limited to 31-bit before they become negative.

* module/mescc/x86_64/as.scm (x86_64:value->r, x86_64:r-cmp-value,
x86_64:r-long-mem-add, x86_64:r-and): Limit M1 immediate to #x80000000.

* lib/tests/scaffold/67-m1-overflow-check.c: New test.
* build-aux/check-mescc.sh (mes_tests): Add it.
--8<---------------cut here---------------end--------------->8---

[..]

> diff --git a/lib/tests/scaffold/67-m1-overflow-check.c 
> b/lib/tests/scaffold/67-m1-overflow-check.c
> +++ b/lib/tests/scaffold/67-m1-overflow-check.c

[..]

> +int main() {
> +  return (0xe5894855 >> 31) - 1;
> +}

Changed to adhere to GNU coding style

--8<---------------cut here---------------start------------->8---
int
main ()
{
  return (0xe5894855 >> 31) - 1;
}
--8<---------------cut here---------------end--------------->8---

> diff --git a/module/mescc/x86_64/as.scm b/module/mescc/x86_64/as.scm
> index 661a5184..6e9cf6d0 100644
> --- a/module/mescc/x86_64/as.scm
> +++ b/module/mescc/x86_64/as.scm

Added a copyright line.  I've put this on wip-x86_64, and rebased
wip-riscv.

Thanks, great work!

Greetings,
Janneke

-- 
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