[PATCH] tree-inline: Fix up __builtin_va_arg_pack handling [PR100898]

[Richard Biener]

On Sun, 6 Jun 2021, Jakub Jelinek wrote:

> Hi!
> 
> The following testcase ICEs, because gimple_call_arg_ptr (..., 0)
> asserts that there is at least one argument, while we were using
> it even if we didn't copy anything just to get a pointer from/to which
> the zero arguments should be copied.
> 
> Fixed by guarding the memcpy calls.  Also, the code was calling
> gimple_call_num_args too many times - 5 times instead of 2, so the patch
> adds two temporaries for those.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

OK.

Richard.

> 2021-06-06  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR middle-end/100898
> 	* tree-inline.c (copy_bb): Only use gimple_call_arg_ptr if memcpy
> 	should copy any arguments.  Don't call gimple_call_num_args
> 	on id->call_stmt or call_stmt more than once.
> 
> 	* g++.dg/ext/va-arg-pack-3.C: New test.
> 
> --- gcc/tree-inline.c.jj	2021-06-04 11:15:26.000000000 +0200
> +++ gcc/tree-inline.c	2021-06-04 15:15:07.358413674 +0200
> @@ -2090,27 +2090,29 @@ copy_bb (copy_body_data *id, basic_block
>  	      tree p;
>  	      gcall *new_call;
>  	      vec<tree> argarray;
> -	      size_t nargs = gimple_call_num_args (id->call_stmt);
> -	      size_t n;
> +	      size_t nargs_caller = gimple_call_num_args (id->call_stmt);
> +	      size_t nargs = nargs_caller;
>  
>  	      for (p = DECL_ARGUMENTS (id->src_fn); p; p = DECL_CHAIN (p))
>  		nargs--;
>  
>  	      /* Create the new array of arguments.  */
> -	      n = nargs + gimple_call_num_args (call_stmt);
> +	      size_t nargs_callee = gimple_call_num_args (call_stmt);
> +	      size_t n = nargs + nargs_callee;
>  	      argarray.create (n);
>  	      argarray.safe_grow_cleared (n, true);
>  
>  	      /* Copy all the arguments before '...'  */
> -	      memcpy (argarray.address (),
> -		      gimple_call_arg_ptr (call_stmt, 0),
> -		      gimple_call_num_args (call_stmt) * sizeof (tree));
> +	      if (nargs_callee)
> +		memcpy (argarray.address (),
> +			gimple_call_arg_ptr (call_stmt, 0),
> +			nargs_callee * sizeof (tree));
>  
>  	      /* Append the arguments passed in '...'  */
> -	      memcpy (argarray.address () + gimple_call_num_args (call_stmt),
> -		      gimple_call_arg_ptr (id->call_stmt, 0)
> -		      + (gimple_call_num_args (id->call_stmt) - nargs),
> -		      nargs * sizeof (tree));
> +	      if (nargs)
> +		memcpy (argarray.address () + nargs_callee,
> +			gimple_call_arg_ptr (id->call_stmt, 0)
> +			+ (nargs_caller - nargs), nargs * sizeof (tree));
>  
>  	      new_call = gimple_build_call_vec (gimple_call_fn (call_stmt),
>  						argarray);
> --- gcc/testsuite/g++.dg/ext/va-arg-pack-3.C.jj	2021-06-04 15:32:28.213079130 +0200
> +++ gcc/testsuite/g++.dg/ext/va-arg-pack-3.C	2021-06-04 15:31:29.777883575 +0200
> @@ -0,0 +1,18 @@
> +// PR middle-end/100898
> +
> +int a;
> +int bar (int, ...);
> +
> +static inline __attribute__((always_inline)) int
> +foo (...)
> +{
> +  while (a)
> +    return bar (0, __builtin_va_arg_pack ());
> +  return 0;
> +}
> +
> +void
> +baz (void)
> +{
> +  foo ();
> +}
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)