PING^1 [PATCH v2] predict: Adjust optimize_function_for_size_p [PR105818]

["Kewen.Lin" <linkw@linux.ibm.com>]

Hi,

Gentle ping: https://gcc.gnu.org/pipermail/gcc-patches/2022-November/607527.html

BR,
Kewen

on 2022/11/30 16:30, Kewen.Lin via Gcc-patches wrote:
> Hi,
> 
> Function optimize_function_for_size_p returns OPTIMIZE_SIZE_NO
> if fun->decl is not null but no cgraph node is available for it.
> As PR105818 shows, this could cause unexpected consequence.  For
> the case in PR105818, when parsing bar decl in function foo, the
> cfun is the function structure for foo, for which there is no
> cgraph node, so it returns OPTIMIZE_SIZE_NO.  But it's incorrect
> since the context is to optimize for size, the flag optimize_size
> is true.
> 
> The patch is to make optimize_function_for_size_p to check
> opt_for_fn (fun->decl, optimize_size) further when fun->decl
> is available but no cgraph node, it's just like what function
> cgraph_node::optimize_for_size_p does at its first step.
> 
> One regression failure got exposed on aarch64-linux-gnu:
> 
> PASS->FAIL: gcc.dg/guality/pr54693-2.c   -Os \
> 	    -DPREVENT_OPTIMIZATION  line 21 x == 10 - i
> 
> The difference comes from the macro LOGICAL_OP_NON_SHORT_CIRCUIT
> used in function fold_range_test during c parsing, it uses
> optimize_function_for_speed_p which is equal to the invertion
> of optimize_function_for_size_p.  At that time cfun->decl is valid
> but no cgraph node for it, w/o this patch function
> optimize_function_for_speed_p returns true eventually, while it
> returns false with this patch.  Since the command line option -Os
> is specified, there is no reason to interpret it as "for speed".
> I think this failure is expected and adjust the test case
> accordingly.
> 
> v1: https://gcc.gnu.org/pipermail/gcc-patches/2022-June/596628.html
> 
> Comparing with v1, v2 adopts opt_for_fn (fun->decl, optimize_size)
> instead of optimize_size as Honza's previous comments.
> 
> Besides, the reply to Honza's question "Why exactly PR105818 hits
> the flag change issue?" was at the link:
> https://gcc.gnu.org/pipermail/gcc-patches/2022-June/596667.html
> 
> Bootstrapped and regtested on x86_64-redhat-linux,
> aarch64-linux-gnu and powerpc64{,le}-linux-gnu.
> 
> Is it for trunk?
> 
> BR,
> Kewen
> -----
> 	PR middle-end/105818
> 
> gcc/ChangeLog:
> 
> 	* predict.cc (optimize_function_for_size_p): Further check
> 	optimize_size of fun->decl when it is valid but no cgraph node.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.target/powerpc/pr105818.c: New test.
> 	* gcc.dg/guality/pr54693-2.c: Adjust for aarch64.
> ---
>  gcc/predict.cc                              |  3 ++-
>  gcc/testsuite/gcc.dg/guality/pr54693-2.c    |  2 +-
>  gcc/testsuite/gcc.target/powerpc/pr105818.c | 11 +++++++++++
>  3 files changed, 14 insertions(+), 2 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/pr105818.c
> 
> diff --git a/gcc/predict.cc b/gcc/predict.cc
> index 1bc7ab94454..ecb4aabc9df 100644
> --- a/gcc/predict.cc
> +++ b/gcc/predict.cc
> @@ -268,7 +268,8 @@ optimize_function_for_size_p (struct function *fun)
>    cgraph_node *n = cgraph_node::get (fun->decl);
>    if (n)
>      return n->optimize_for_size_p ();
> -  return OPTIMIZE_SIZE_NO;
> +  return opt_for_fn (fun->decl, optimize_size) ? OPTIMIZE_SIZE_MAX
> +					       : OPTIMIZE_SIZE_NO;
>  }
> 
>  /* Return true if function FUN should always be optimized for speed.  */
> diff --git a/gcc/testsuite/gcc.dg/guality/pr54693-2.c b/gcc/testsuite/gcc.dg/guality/pr54693-2.c
> index 68aa6c63d71..14ca94ad37d 100644
> --- a/gcc/testsuite/gcc.dg/guality/pr54693-2.c
> +++ b/gcc/testsuite/gcc.dg/guality/pr54693-2.c
> @@ -17,7 +17,7 @@ foo (int x, int y, int z)
>    int i = 0;
>    while (x > 3 && y > 3 && z > 3)
>      {		/* { dg-final { gdb-test .+2 "i" "v + 1" } } */
> -		/* { dg-final { gdb-test .+1 "x" "10 - i" } } */
> +		/* { dg-final { gdb-test .+1 "x" "10 - i" { xfail { aarch64*-*-* && { any-opts "-Os" } } } } } */
>        bar (i);	/* { dg-final { gdb-test . "y" "20 - 2 * i" } } */
>  		/* { dg-final { gdb-test .-1 "z" "30 - 3 * i" { xfail { aarch64*-*-* && { any-opts "-fno-fat-lto-objects" "-Os" } } } } } */
>        i++, x--, y -= 2, z -= 3;
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr105818.c b/gcc/testsuite/gcc.target/powerpc/pr105818.c
> new file mode 100644
> index 00000000000..679647e189d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr105818.c
> @@ -0,0 +1,11 @@
> +/* { dg-options "-Os -fno-tree-vectorize" } */
> +
> +/* Verify there is no ICE.  */
> +
> +#pragma GCC optimize "-fno-tree-vectorize"
> +
> +void
> +foo (void)
> +{
> +  void bar (void);
> +}
> --
> 2.27.0