Re: [PATCH] Fix -minline-stringops-dynamically (PR target/69432)

[Jan Hubicka <hubicka at ucw dot cz>]

> Hi!
> 
> With this option we generate a conditional library call.  When expanding
> such a call, do_pending_stack_adjust () is performed from expand_call
> and if there are any needed sp adjustments, they are emitted.  The
> problem is that this happens only in conditionally executed code, so on some
> path the args size level will be correct, on others it might be wrong.
> 
> Fixed by doing the adjustment before the first conditional jump if we know
> we'll emit a call conditionally.  Bootstrapped/regtested on x86_64-linux and
> i686-linux, ok for trunk?
> 
> BTW, when looking at this, I've noticed something strange,
> expand_set_or_movmem_prologue_epilogue_by_misaligned_moves has bool
> dynamic_check argument, but the caller has int dynamic_check and in the
> caller as I understand the meaning is dynamic_check == -1 means no
> conditional library call, otherwise there is a conditional library call with
> some specific max size.  When calling
> expand_set_or_movmem_prologue_epilogue_by_misaligned_moves, the
> dynamic_check value is passed to the bool argument though, so that means
> dynamic_check != 0 instead of dynamic_check != -1.  Honza, can you please
> have a look at that?

Yep, that indeed looks odd.  I will take a look.

Path is OK.

Thanks,
Honza
> 
> 2016-01-22  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR target/69432
> 	* config/i386/i386.c: Include dojump.h.
> 	(expand_small_movmem_or_setmem,
> 	expand_set_or_movmem_prologue_epilogue_by_misaligned_moves): Spelling
> 	fixes.
> 	(ix86_expand_set_or_movmem): Call do_pending_stack_adjust () early
> 	if dynamic_check != -1.
> 
> 	* g++.dg/opt/pr69432.C: New test.
> 
> --- gcc/config/i386/i386.c.jj	2016-01-19 09:20:34.000000000 +0100
> +++ gcc/config/i386/i386.c	2016-01-22 20:39:32.289457234 +0100
> @@ -75,6 +75,7 @@ along with GCC; see the file COPYING3.
>  #include "dbgcnt.h"
>  #include "case-cfn-macros.h"
>  #include "regrename.h"
> +#include "dojump.h"
>  
>  /* This file should be included last.  */
>  #include "target-def.h"
> @@ -25700,7 +25701,7 @@ expand_small_movmem_or_setmem (rtx destm
>         if (DYNAMIC_CHECK)
>  	 Round COUNT down to multiple of SIZE
>         << optional caller supplied zero size guard is here >>
> -       << optional caller suppplied dynamic check is here >>
> +       << optional caller supplied dynamic check is here >>
>         << caller supplied main copy loop is here >>
>       }
>     done_label:
> @@ -25875,8 +25876,8 @@ expand_set_or_movmem_prologue_epilogue_b
>        else
>  	*min_size = 0;
>  
> -      /* Our loops always round down the bock size, but for dispatch to library
> -	 we need precise value.  */
> +      /* Our loops always round down the block size, but for dispatch to
> +         library we need precise value.  */
>        if (dynamic_check)
>  	*count = expand_simple_binop (GET_MODE (*count), AND, *count,
>  				      GEN_INT (-size), *count, 1, OPTAB_DIRECT);
> @@ -26469,6 +26470,13 @@ ix86_expand_set_or_movmem (rtx dst, rtx
>    size_needed = GET_MODE_SIZE (move_mode) * unroll_factor;
>    epilogue_size_needed = size_needed;
>  
> +  /* If we are going to call any library calls conditionally, make sure any
> +     pending stack adjustment happen before the first conditional branch,
> +     otherwise they will be emitted before the library call only and won't
> +     happen from the other branches.  */
> +  if (dynamic_check != -1)
> +    do_pending_stack_adjust ();
> +
>    desired_align = decide_alignment (align, alg, expected_size, move_mode);
>    if (!TARGET_ALIGN_STRINGOPS || noalign)
>      align = desired_align;
> --- gcc/testsuite/g++.dg/opt/pr69432.C.jj	2016-01-22 20:51:19.463428357 +0100
> +++ gcc/testsuite/g++.dg/opt/pr69432.C	2016-01-22 20:51:04.000000000 +0100
> @@ -0,0 +1,62 @@
> +// PR target/69432
> +// { dg-do compile }
> +// { dg-options "-O3" }
> +// { dg-additional-options "-minline-stringops-dynamically" { target i?86-*-* x86_64-*-* } }
> +
> +template <typename S, typename T, typename U>
> +void
> +f1 (S x, T y, U z)
> +{
> +  for (; y; --y, ++x)
> +    *x = z;
> +}
> +
> +template <typename S, typename T, typename U>
> +void f2 (S x, T y, U z)
> +{
> +  f1 (x, y, z);
> +}
> +
> +struct A {};
> +struct B { static char f3 (A, unsigned); };
> +
> +template <typename S, typename U>
> +void f4 (S, U);
> +
> +struct C
> +{
> +  template <typename S, typename T, typename U>
> +  static S f5 (S x, T y, U z) { f2 (x, y, z); }
> +};
> +
> +template <typename S, typename T, typename U>
> +void f6 (S x, T y, U z) { C::f5 (x, y, z); }
> +
> +template <typename S, typename T, typename U, typename V>
> +void f7 (S x, T y, U z, V) { f6 (x, y, z); }
> +
> +struct E
> +{
> +  struct D : A { char e; D (A); };
> +  A f;
> +  E (int x) : g(f) { f8 (x); }
> +  ~E ();
> +  D g;
> +  void f9 (int x) { x ? B::f3 (g, x) : char (); }
> +  void f8 (int x) { f9 (x); }
> +};
> +
> +struct F : E
> +{
> +  F (int x) : E(x) { f10 (x); f4 (this, 0); }
> +  char h;
> +  void f10 (int x) { f7 (&g.e, x, h, 0); }
> +};
> +
> +long a;
> +
> +void
> +test ()
> +{
> +  F b(a);
> +}
> 
> 	Jakub