On Mon, 18 Mar 2019, Jakub Jelinek wrote:
> Hi!
>
> For input arguments, we do:
> /* If we can't make copies, we can only accept memory. */
> if (TREE_ADDRESSABLE (TREE_TYPE (TREE_VALUE (link))))
> {
> if (allows_mem)
> allows_reg = 0;
> else
> {
> error ("impossible constraint in %<asm%>");
> error ("non-memory input %d must stay in memory", i);
> return GS_ERROR;
> }
> }
> The following patch does the same thing for output operands as well.
> For the cases where !allows_mem, that will just result in one extra error
> explaining what's going on (previously one would get the
> impossible constraint in %<asm%> error during vregs pass, now it gets
> during gimplification + the extra error too), and if allows_mem,
> it will for the + case make sure we get "=rm" (x) ... : "rm" (x) instead
> of "=rm" (x) ... : "0" (x) that LRA ICEs on.
>
> While the LRA ICE needs to be fixed in any case (one can still reproduce it
> with
> __asm volatile ("" : "=rm" (a0), "=rm" (a1) : "0" (a0), "1" (a1));
> ), this patch opens the possibility to accept "+rm" (a0) and reject
> "=rm" (a0) ... "0" (a0) if reload can't prove it is the same address.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Richard.
> 2019-03-18 Jakub Jelinek <ja...@redhat.com>
>
> PR target/89752
> * gimplify.c (gimplify_asm_expr): For output argument with
> TREE_ADDRESSABLE type, clear allows_reg if it allows memory, otherwise
> diagnose error.
>
> * g++.dg/ext/asm15.C: Check for particular diagnostic wording.
> * g++.dg/ext/asm16.C: Likewise.
> * g++.dg/ext/asm17.C: New test.
>
> --- gcc/gimplify.c.jj 2019-03-07 20:45:39.168938360 +0100
> +++ gcc/gimplify.c 2019-03-18 16:18:16.515466234 +0100
> @@ -6155,6 +6155,19 @@ gimplify_asm_expr (tree *expr_p, gimple_
> is_inout = false;
> }
>
> + /* If we can't make copies, we can only accept memory. */
> + if (TREE_ADDRESSABLE (TREE_TYPE (TREE_VALUE (link))))
> + {
> + if (allows_mem)
> + allows_reg = 0;
> + else
> + {
> + error ("impossible constraint in %<asm%>");
> + error ("non-memory output %d must stay in memory", i);
> + return GS_ERROR;
> + }
> + }
> +
> if (!allows_reg && allows_mem)
> mark_addressable (TREE_VALUE (link));
>
> --- gcc/testsuite/g++.dg/ext/asm15.C.jj 2018-05-06 23:13:33.252652046
> +0200
> +++ gcc/testsuite/g++.dg/ext/asm15.C 2019-03-18 18:00:48.907456236 +0100
> @@ -6,5 +6,6 @@ struct S { S (); ~S (); int s; };
> void
> foo (S &s)
> {
> - __asm volatile ("" : "+r" (s) : : "memory"); // { dg-error "" }
> + __asm volatile ("" : "+r" (s) : : "memory"); // { dg-error
> "impossible constraint" }
> + // { dg-error "must stay in
> memory" "" { target *-*-* } .-1 }
> }
> --- gcc/testsuite/g++.dg/ext/asm16.C.jj 2018-05-06 23:13:33.252652046
> +0200
> +++ gcc/testsuite/g++.dg/ext/asm16.C 2019-03-18 18:00:35.978664187 +0100
> @@ -6,5 +6,6 @@ struct S { S (); ~S (); int s[64]; } s;
> void
> foo ()
> {
> - __asm volatile ("" : "=r" (s) : : "memory"); // { dg-error "" }
> + __asm volatile ("" : "=r" (s) : : "memory"); // { dg-error
> "impossible constraint" }
> + // { dg-error "must stay in
> memory" "" { target *-*-* } .-1 }
> }
> --- gcc/testsuite/g++.dg/ext/asm17.C.jj 2019-03-18 17:57:44.409424473
> +0100
> +++ gcc/testsuite/g++.dg/ext/asm17.C 2019-03-18 17:58:32.414651932 +0100
> @@ -0,0 +1,11 @@
> +// PR target/89752
> +// { dg-do compile }
> +
> +struct A { A (); ~A (); short c; };
> +
> +void
> +foo ()
> +{
> + A a0, a1;
> + __asm volatile ("" : "+rm" (a0), "+rm" (a1));
> +}
>
> Jakub
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
