Re: [PATCH] lower-bitint: Handle unreleased SSA_NAMEs from earlier passes gracefully [PR113102]

[Richard Biener <rguenther@suse.de>]

> Am 22.12.2023 um 09:17 schrieb Jakub Jelinek <jakub@redhat.com>:
> 
> Hi!
> 
> On the following testcase earlier passes leave around an unreleased
> SSA_NAME - non-GIMPLE_NOP SSA_NAME_DEF_STMT which isn't in any bb.
> The following patch makes bitint lowering resistent against those,
> the first hunk is where we'd for certain kinds of stmts try to ammend
> them and the latter is where we'd otherwise try to remove them,
> neither of which works.  The other loops over all SSA_NAMEs either
> already also check gimple_bb (SSA_NAME_DEF_STMT (s)) or it doesn't
> matter that much if we process it or not (worst case it means e.g.
> the pass wouldn't return early even when it otherwise could).
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Ok

> 2023-12-22  Jakub Jelinek  <jakub@redhat.com>
> 
>    PR tree-optimization/113102
>    * gimple-lower-bitint.cc (gimple_lower_bitint): Handle unreleased
>    large/huge _BitInt SSA_NAMEs.
> 
>    * gcc.dg/bitint-59.c: New test.
> 
> --- gcc/gimple-lower-bitint.cc.jj    2023-12-21 13:28:56.953120687 +0100
> +++ gcc/gimple-lower-bitint.cc    2023-12-21 14:08:00.199704511 +0100
> @@ -5827,7 +5827,7 @@ gimple_lower_bitint (void)
>      tree_code rhs_code;
>      /* Unoptimize certain constructs to simpler alternatives to
>         avoid having to lower all of them.  */
> -      if (is_gimple_assign (stmt))
> +      if (is_gimple_assign (stmt) && gimple_bb (stmt))
>        switch (rhs_code = gimple_assign_rhs_code (stmt))
>          {
>          default:
> @@ -6690,6 +6690,11 @@ gimple_lower_bitint (void)
>          release_ssa_name (s);
>          continue;
>        }
> +          if (gimple_bb (g) == NULL)
> +        {
> +          release_ssa_name (s);
> +          continue;
> +        }
>          if (gimple_code (g) != GIMPLE_ASM)
>        {
>          gimple_stmt_iterator gsi = gsi_for_stmt (g);
> --- gcc/testsuite/gcc.dg/bitint-59.c.jj    2023-12-21 14:12:01.860350727 +0100
> +++ gcc/testsuite/gcc.dg/bitint-59.c    2023-12-21 14:11:54.766449179 +0100
> @@ -0,0 +1,14 @@
> +/* PR tree-optimization/113102 */
> +/* { dg-do compile { target bitint } } */
> +/* { dg-options "-std=c23 -O2" } */
> +
> +unsigned x;
> +
> +#if __BITINT_MAXWIDTH__ >= 191
> +void
> +foo (void)
> +{
> +  unsigned _BitInt(191) b = x;
> +  ~(b >> x) % 3;
> +}
> +#endif
> 
>    Jakub
>