https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
andysem at mail dot ru changed:
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
nsz at gcc dot gnu.org changed:
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
--- Comment #12 from Richard Earnshaw ---
We considered that, but it won't work. For example, in ILP32 address registers
need to use the X form, but are still 32-bits in size. There are other cases
as well where a W or X form is required but
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
--- Comment #11 from Jeremy ---
int32_t n;
asm( "str %1,[%0],#4" : "+r" (ptr) : "r" (n) : "memory" );
Caught me until I just happened to examine the assembler.
Of course %w1 works - but then I need SEPARATE code for 32-bit ARM and for
aarch64.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
Andrew Pinski changed:
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--- Comment #10 from
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
James Molloy james.molloy at arm dot com changed:
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
--- Comment #2 from Marc Glisse glisse at gcc dot gnu.org ---
(In reply to James Molloy from comment #1)
Besides, clang rejects it, so please find a common syntax...
It shouldn't. The w modifier should have been supported since clang 3.4,
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
Richard Earnshaw rearnsha at gcc dot gnu.org changed:
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
--- Comment #4 from James Molloy james.molloy at arm dot com ---
Hi Richard,
My two-pennyworth for what it's worth - we've had several people with broken
code tripped by this bug, and Apple have reported seeing the same thing with
their internal
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
--- Comment #5 from Richard Earnshaw rearnsha at gcc dot gnu.org ---
So consider:
int f(int i){
long x;
asm(lsl %0, %1, 33 : =r(x) : r(i)); // lshift by more than sizeof(int)
return x;
}
We really don't care about the top bits in i, so we
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
--- Comment #6 from James Molloy james.molloy at arm dot com ---
Good example, although I might argue slightly pathological.
So in this case currently, GCC doesn't even implicitly promote the argument,
just uses it as-is. It seems a very
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
--- Comment #7 from Marc Glisse glisse at gcc dot gnu.org ---
(In reply to Richard Earnshaw from comment #3)
I'm not so sure about a warning, however. I could envisage cases where the
warning would be incorrect and avoiding it would lead to
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--- Comment #8 from Richard Earnshaw rearnsha at gcc dot gnu.org ---
(In reply to James Molloy from comment #6)
Good example, although I might argue slightly pathological.
Agreed, this is somewhat pathological, but I only need to find one
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
--- Comment #9 from James Molloy james.molloy at arm dot com ---
OK, given your second example I agree that the usecase isn't quite as
pathological as I thought.
I'm not saying I'll never accept a warning for this sort of code; but I'd need
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