diff mbox series

[v2] tree-optimization/107389 - honor __builtin_assume_alignment at -O0

Message ID 20221108125348.BFC2213398@imap2.suse-dmz.suse.de
State Accepted
Headers
Series [v2] tree-optimization/107389 - honor __builtin_assume_alignment at -O0 |

Checks

Context Check Description
snail/gcc-patch-check success Github commit url

Commit Message

Richard Biener Nov. 8, 2022, 12:53 p.m. UTC 
  The following makes sure to set alignment information on the LHS
of __builtin_assume_alignment calls even when not optimizing so
uses as arguments to builtin functions like memcpy or __atomic_load_n
can be reflected at RTL expansion time.

Bootstrap and regtest running on x86_64-unknown-linux-gnu, OK?

Thanks,
Richard.

	PR tree-optimization/107389
	* gimple-low.cc (lower_builtin_assume_aligned): New.
	(lower_stmt): Call it.

	* gcc.dg/pr107389.c: New testcase.
---
 gcc/gimple-low.cc               | 41 +++++++++++++++++++++++++++++++++
 gcc/testsuite/gcc.dg/pr107389.c | 13 +++++++++++
 2 files changed, 54 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/pr107389.c

Comments

Jakub Jelinek Nov. 8, 2022, 1:05 p.m. UTC | #1 
On Tue, Nov 08, 2022 at 01:53:48PM +0100, Richard Biener wrote:
> The following makes sure to set alignment information on the LHS
> of __builtin_assume_alignment calls even when not optimizing so
> uses as arguments to builtin functions like memcpy or __atomic_load_n
> can be reflected at RTL expansion time.
> 
> Bootstrap and regtest running on x86_64-unknown-linux-gnu, OK?
> 
> Thanks,
> Richard.
> 
> 	PR tree-optimization/107389
> 	* gimple-low.cc (lower_builtin_assume_aligned): New.
> 	(lower_stmt): Call it.
> 
> 	* gcc.dg/pr107389.c: New testcase.
> ---
>  gcc/gimple-low.cc               | 41 +++++++++++++++++++++++++++++++++
>  gcc/testsuite/gcc.dg/pr107389.c | 13 +++++++++++
>  2 files changed, 54 insertions(+)
>  create mode 100644 gcc/testsuite/gcc.dg/pr107389.c
> 
> diff --git a/gcc/gimple-low.cc b/gcc/gimple-low.cc
> index 512aa9feada..f9bcb772163 100644
> --- a/gcc/gimple-low.cc
> +++ b/gcc/gimple-low.cc
> @@ -84,6 +84,7 @@ static void lower_try_catch (gimple_stmt_iterator *, struct lower_data *);
>  static void lower_gimple_return (gimple_stmt_iterator *, struct lower_data *);
>  static void lower_builtin_setjmp (gimple_stmt_iterator *);
>  static void lower_builtin_posix_memalign (gimple_stmt_iterator *);
> +static void lower_builtin_assume_aligned (gimple_stmt_iterator *);
>  
>  
>  /* Lower the body of current_function_decl from High GIMPLE into Low
> @@ -768,6 +769,13 @@ lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
>  		lower_builtin_posix_memalign (gsi);
>  		return;
>  	      }
> +	    else if (DECL_FUNCTION_CODE (decl) == BUILT_IN_ASSUME_ALIGNED
> +		     && !optimize)
> +	      {
> +		lower_builtin_assume_aligned (gsi);
> +		data->cannot_fallthru = false;
> +		return;
> +	      }
>  	  }
>  
>  	if (decl && (flags_from_decl_or_type (decl) & ECF_NORETURN))
> @@ -1310,6 +1318,39 @@ lower_builtin_posix_memalign (gimple_stmt_iterator *gsi)
>    gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
>    gsi_insert_after (gsi, gimple_build_label (noalign_label), GSI_NEW_STMT);
>  }
> +
> +/* Lower calls to __builtin_assume_aligned when not optimizing.  */
> +
> +static void
> +lower_builtin_assume_aligned (gimple_stmt_iterator *gsi)
> +{
> +  gcall *call = as_a <gcall *> (gsi_stmt (*gsi));
> +
> +  tree lhs = gimple_call_lhs (call);
> +  if (!lhs || !POINTER_TYPE_P (TREE_TYPE (lhs)))
> +    return;

I think nothing checks that TREE_CODE (lhs) == SSA_NAME,
that isn't guaranteed before ssa pass.
Otherwise LGTM.

	Jakub
Richard Biener Nov. 8, 2022, 1:38 p.m. UTC | #2 
On Tue, 8 Nov 2022, Jakub Jelinek wrote:

> On Tue, Nov 08, 2022 at 01:53:48PM +0100, Richard Biener wrote:
> > The following makes sure to set alignment information on the LHS
> > of __builtin_assume_alignment calls even when not optimizing so
> > uses as arguments to builtin functions like memcpy or __atomic_load_n
> > can be reflected at RTL expansion time.
> > 
> > Bootstrap and regtest running on x86_64-unknown-linux-gnu, OK?
> > 
> > Thanks,
> > Richard.
> > 
> > 	PR tree-optimization/107389
> > 	* gimple-low.cc (lower_builtin_assume_aligned): New.
> > 	(lower_stmt): Call it.
> > 
> > 	* gcc.dg/pr107389.c: New testcase.
> > ---
> >  gcc/gimple-low.cc               | 41 +++++++++++++++++++++++++++++++++
> >  gcc/testsuite/gcc.dg/pr107389.c | 13 +++++++++++
> >  2 files changed, 54 insertions(+)
> >  create mode 100644 gcc/testsuite/gcc.dg/pr107389.c
> > 
> > diff --git a/gcc/gimple-low.cc b/gcc/gimple-low.cc
> > index 512aa9feada..f9bcb772163 100644
> > --- a/gcc/gimple-low.cc
> > +++ b/gcc/gimple-low.cc
> > @@ -84,6 +84,7 @@ static void lower_try_catch (gimple_stmt_iterator *, struct lower_data *);
> >  static void lower_gimple_return (gimple_stmt_iterator *, struct lower_data *);
> >  static void lower_builtin_setjmp (gimple_stmt_iterator *);
> >  static void lower_builtin_posix_memalign (gimple_stmt_iterator *);
> > +static void lower_builtin_assume_aligned (gimple_stmt_iterator *);
> >  
> >  
> >  /* Lower the body of current_function_decl from High GIMPLE into Low
> > @@ -768,6 +769,13 @@ lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
> >  		lower_builtin_posix_memalign (gsi);
> >  		return;
> >  	      }
> > +	    else if (DECL_FUNCTION_CODE (decl) == BUILT_IN_ASSUME_ALIGNED
> > +		     && !optimize)
> > +	      {
> > +		lower_builtin_assume_aligned (gsi);
> > +		data->cannot_fallthru = false;
> > +		return;
> > +	      }
> >  	  }
> >  
> >  	if (decl && (flags_from_decl_or_type (decl) & ECF_NORETURN))
> > @@ -1310,6 +1318,39 @@ lower_builtin_posix_memalign (gimple_stmt_iterator *gsi)
> >    gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
> >    gsi_insert_after (gsi, gimple_build_label (noalign_label), GSI_NEW_STMT);
> >  }
> > +
> > +/* Lower calls to __builtin_assume_aligned when not optimizing.  */
> > +
> > +static void
> > +lower_builtin_assume_aligned (gimple_stmt_iterator *gsi)
> > +{
> > +  gcall *call = as_a <gcall *> (gsi_stmt (*gsi));
> > +
> > +  tree lhs = gimple_call_lhs (call);
> > +  if (!lhs || !POINTER_TYPE_P (TREE_TYPE (lhs)))
> > +    return;
> 
> I think nothing checks that TREE_CODE (lhs) == SSA_NAME,
> that isn't guaranteed before ssa pass.

Yep, noticed in the testsuite and fixed.

Richard.
diff mbox series

Patch

diff --git a/gcc/gimple-low.cc b/gcc/gimple-low.cc
index 512aa9feada..f9bcb772163 100644
--- a/gcc/gimple-low.cc
+++ b/gcc/gimple-low.cc
@@ -84,6 +84,7 @@  static void lower_try_catch (gimple_stmt_iterator *, struct lower_data *);
 static void lower_gimple_return (gimple_stmt_iterator *, struct lower_data *);
 static void lower_builtin_setjmp (gimple_stmt_iterator *);
 static void lower_builtin_posix_memalign (gimple_stmt_iterator *);
+static void lower_builtin_assume_aligned (gimple_stmt_iterator *);
 
 
 /* Lower the body of current_function_decl from High GIMPLE into Low
@@ -768,6 +769,13 @@  lower_stmt (gimple_stmt_iterator *gsi, struct lower_data *data)
 		lower_builtin_posix_memalign (gsi);
 		return;
 	      }
+	    else if (DECL_FUNCTION_CODE (decl) == BUILT_IN_ASSUME_ALIGNED
+		     && !optimize)
+	      {
+		lower_builtin_assume_aligned (gsi);
+		data->cannot_fallthru = false;
+		return;
+	      }
 	  }
 
 	if (decl && (flags_from_decl_or_type (decl) & ECF_NORETURN))
@@ -1310,6 +1318,39 @@  lower_builtin_posix_memalign (gimple_stmt_iterator *gsi)
   gsi_insert_after (gsi, stmt, GSI_NEW_STMT);
   gsi_insert_after (gsi, gimple_build_label (noalign_label), GSI_NEW_STMT);
 }
+
+/* Lower calls to __builtin_assume_aligned when not optimizing.  */
+
+static void
+lower_builtin_assume_aligned (gimple_stmt_iterator *gsi)
+{
+  gcall *call = as_a <gcall *> (gsi_stmt (*gsi));
+
+  tree lhs = gimple_call_lhs (call);
+  if (!lhs || !POINTER_TYPE_P (TREE_TYPE (lhs)))
+    return;
+
+  tree align = gimple_call_arg (call, 1);
+  tree misalign = (gimple_call_num_args (call) > 2
+		   ? gimple_call_arg (call, 2) : NULL_TREE);
+  if (!tree_fits_uhwi_p (align)
+      || (misalign && !tree_fits_uhwi_p (misalign)))
+    return;
+
+  unsigned aligni = TREE_INT_CST_LOW (align);
+  unsigned misaligni = misalign ? TREE_INT_CST_LOW (misalign) : 0;
+  if (aligni <= 1
+      || (aligni & (aligni - 1)) != 0
+      || (misaligni & ~(aligni - 1)) != 0)
+    return;
+
+  /* For lowering we simply transfer alignment information to the
+     result and leave the call otherwise unchanged, it will be elided
+     at RTL expansion time.  */
+  ptr_info_def *pi = get_ptr_info (lhs);
+  set_ptr_info_alignment (pi, aligni, misaligni);
+  gsi_next (gsi);
+}
 
 
 /* Record the variables in VARS into function FN.  */
diff --git a/gcc/testsuite/gcc.dg/pr107389.c b/gcc/testsuite/gcc.dg/pr107389.c
new file mode 100644
index 00000000000..deb63380704
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr107389.c
@@ -0,0 +1,13 @@ 
+/* { dg-do compile } */
+/* { dg-options "-fdump-tree-optimized-alias" } */
+
+unsigned foo (void *p)
+{
+  unsigned i;
+  __builtin_memcpy (&i, __builtin_assume_aligned (p, 4), sizeof (unsigned));
+  return i;
+}
+
+/* Even when not optimizing we should have alignment info on the temporary
+   feeding the memcpy.  */
+/* { dg-final { scan-tree-dump "ALIGN = 4" "optimized" } } */