diff mbox series

middle-end: don't keep .MEM guard nodes for PHI nodes who dominate loop [PR111860]

Message ID patch-17863-tamar@arm.com
State Not Applicable
Headers
Series middle-end: don't keep .MEM guard nodes for PHI nodes who dominate loop [PR111860] |

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Commit Message

Tamar Christina Oct. 20, 2023, 1:55 p.m. UTC 
  Hi All,

The previous patch tried to remove PHI nodes that dominated the first loop,
however the correct fix is to only remove .MEM nodes.

This patch thus makes the condition a bit stricter and only tries to remove
MEM phi nodes.

I couldn't figure out a way to easily determine if a particular PHI is vUSE
related, so the patch does:

1. check if the definition is a vDEF and not defined in main loop.
2. check if the definition is a PHI and not defined in main loop. 
3. check if the definition is a default definition.

For no 2 and 3 we may misidentify the PHI, in both cases the value is defined
outside of the loop version block which also makes it ok to remove.

Bootstrapped Regtested on aarch64-none-linux-gnu, powerpc64le-unknown-linux-gnu,
x86_64-none-linux-gnu and no issues.

Tested all default testsuites.

Ok for master?

Thanks,
Tamar

gcc/ChangeLog:

	PR tree-optimization/111860
	* tree-vect-loop-manip.cc (slpeel_tree_duplicate_loop_to_edge_cfg):
	Drop .MEM nodes only.

gcc/testsuite/ChangeLog:

	PR tree-optimization/111860
	* gcc.dg/vect/pr111860-2.c: New test.
	* gcc.dg/vect/pr111860-3.c: New test.

--- inline copy of patch -- 
diff --git a/gcc/testsuite/gcc.dg/vect/pr111860-2.c b/gcc/testsuite/gcc.dg/vect/pr111860-2.c
new file mode 100644
index 0000000000000000000000000000000000000000..07f64ffb5318c9d7817d46802d123cc9a2d65ec9




--
diff --git a/gcc/testsuite/gcc.dg/vect/pr111860-2.c b/gcc/testsuite/gcc.dg/vect/pr111860-2.c
new file mode 100644
index 0000000000000000000000000000000000000000..07f64ffb5318c9d7817d46802d123cc9a2d65ec9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr111860-2.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fno-tree-sink -ftree-vectorize" } */
+int buffer_ctrl_ctx_0, buffer_ctrl_p1, buffer_ctrl_cmd;
+
+int
+buffer_ctrl (long ret, int i)
+{
+  switch (buffer_ctrl_cmd)
+    {
+    case 1:
+      buffer_ctrl_ctx_0 = 0;
+      for (; i; i++)
+	if (buffer_ctrl_p1)
+	  ret++;
+    }
+  return ret;
+}
diff --git a/gcc/testsuite/gcc.dg/vect/pr111860-3.c b/gcc/testsuite/gcc.dg/vect/pr111860-3.c
new file mode 100644
index 0000000000000000000000000000000000000000..07f64ffb5318c9d7817d46802d123cc9a2d65ec9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr111860-3.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fno-tree-sink -ftree-vectorize" } */
+int buffer_ctrl_ctx_0, buffer_ctrl_p1, buffer_ctrl_cmd;
+
+int
+buffer_ctrl (long ret, int i)
+{
+  switch (buffer_ctrl_cmd)
+    {
+    case 1:
+      buffer_ctrl_ctx_0 = 0;
+      for (; i; i++)
+	if (buffer_ctrl_p1)
+	  ret++;
+    }
+  return ret;
+}
diff --git a/gcc/testsuite/gcc.dg/vect/pr111860.c b/gcc/testsuite/gcc.dg/vect/pr111860.c
new file mode 100644
index 0000000000000000000000000000000000000000..36f0774601040418bc6b7f27c9425b2bf93b18cb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr111860.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+
+int optimize_path_n, optimize_path_d;
+int *optimize_path_d_0;
+extern void path_threeOpt( long);
+void optimize_path() {
+  int i;
+  long length;
+  i = 0;
+  for (; i <= optimize_path_n; i++)
+    optimize_path_d = 0;
+  i = 0;
+  for (; i < optimize_path_n; i++)
+    length += optimize_path_d_0[i];
+  path_threeOpt(length);
+}
diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
index 1f7779b9834c3aef3c6a993fab916224fab03147..fc55278e63f7a48943fdc32c5e207110cf14507e 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -1626,13 +1626,33 @@ slpeel_tree_duplicate_loop_to_edge_cfg (class loop *loop, edge loop_exit,
 	  edge temp_e = redirect_edge_and_branch (exit, new_preheader);
 	  flush_pending_stmts (temp_e);
 	}
-
       /* Record the new SSA names in the cache so that we can skip materializing
 	 them again when we fill in the rest of the LCSSA variables.  */
       for (auto phi : new_phis)
 	{
 	  tree new_arg = gimple_phi_arg (phi, 0)->def;
 	  new_phi_args.put (new_arg, gimple_phi_result (phi));
+
+	  if (!SSA_VAR_P (new_arg))
+	    continue;
+	  /* If the PHI MEM node dominates the loop then we shouldn't create
+	      a new LC-SSSA PHI for it in the intermediate block.   */
+	  gimple *def_stmt = SSA_NAME_DEF_STMT (new_arg);
+	  basic_block def_bb = gimple_bb (def_stmt);
+	  /* A MEM phi that consitutes a new DEF for the vUSE chain can either
+	     be a .VDEF or a PHI that operates on MEM.  */
+	  if (((gimple_vdef (def_stmt) || is_a <gphi *> (def_stmt))
+		  /* And said definition must not be inside the main loop.  */
+	       && (!def_bb || !flow_bb_inside_loop_p (loop, def_bb)))
+	      /* Or we must be a parameter.  In the last two cases we may remove
+		 a non-MEM PHI node, but since they dominate both loops the
+		 removal is unlikely to cause trouble as the exits must already
+		 be using them.  */
+	      || SSA_NAME_IS_DEFAULT_DEF (new_arg))
+	    {
+	      auto gsi = gsi_for_stmt (phi);
+	      remove_phi_node (&gsi, true);
+	    }
 	}
 
       /* Copy the current loop LC PHI nodes between the original loop exit

Comments

Richard Biener Oct. 23, 2023, 8:21 a.m. UTC | #1 
On Fri, 20 Oct 2023, Tamar Christina wrote:

> Hi All,
> 
> The previous patch tried to remove PHI nodes that dominated the first loop,
> however the correct fix is to only remove .MEM nodes.
> 
> This patch thus makes the condition a bit stricter and only tries to remove
> MEM phi nodes.
> 
> I couldn't figure out a way to easily determine if a particular PHI is vUSE
> related, so the patch does:
> 
> 1. check if the definition is a vDEF and not defined in main loop.
> 2. check if the definition is a PHI and not defined in main loop. 
> 3. check if the definition is a default definition.
> 
> For no 2 and 3 we may misidentify the PHI, in both cases the value is defined
> outside of the loop version block which also makes it ok to remove.
> 
> Bootstrapped Regtested on aarch64-none-linux-gnu, powerpc64le-unknown-linux-gnu,
> x86_64-none-linux-gnu and no issues.
> 
> Tested all default testsuites.
> 
> Ok for master?
> 
> Thanks,
> Tamar
> 
> gcc/ChangeLog:
> 
> 	PR tree-optimization/111860
> 	* tree-vect-loop-manip.cc (slpeel_tree_duplicate_loop_to_edge_cfg):
> 	Drop .MEM nodes only.
> 
> gcc/testsuite/ChangeLog:
> 
> 	PR tree-optimization/111860
> 	* gcc.dg/vect/pr111860-2.c: New test.
> 	* gcc.dg/vect/pr111860-3.c: New test.
> 
> --- inline copy of patch -- 
> diff --git a/gcc/testsuite/gcc.dg/vect/pr111860-2.c b/gcc/testsuite/gcc.dg/vect/pr111860-2.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..07f64ffb5318c9d7817d46802d123cc9a2d65ec9
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/vect/pr111860-2.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O -fno-tree-sink -ftree-vectorize" } */
> +int buffer_ctrl_ctx_0, buffer_ctrl_p1, buffer_ctrl_cmd;
> +
> +int
> +buffer_ctrl (long ret, int i)
> +{
> +  switch (buffer_ctrl_cmd)
> +    {
> +    case 1:
> +      buffer_ctrl_ctx_0 = 0;
> +      for (; i; i++)
> +	if (buffer_ctrl_p1)
> +	  ret++;
> +    }
> +  return ret;
> +}
> diff --git a/gcc/testsuite/gcc.dg/vect/pr111860-3.c b/gcc/testsuite/gcc.dg/vect/pr111860-3.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..07f64ffb5318c9d7817d46802d123cc9a2d65ec9
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/vect/pr111860-3.c
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O -fno-tree-sink -ftree-vectorize" } */
> +int buffer_ctrl_ctx_0, buffer_ctrl_p1, buffer_ctrl_cmd;
> +
> +int
> +buffer_ctrl (long ret, int i)
> +{
> +  switch (buffer_ctrl_cmd)
> +    {
> +    case 1:
> +      buffer_ctrl_ctx_0 = 0;
> +      for (; i; i++)
> +	if (buffer_ctrl_p1)
> +	  ret++;
> +    }
> +  return ret;
> +}
> diff --git a/gcc/testsuite/gcc.dg/vect/pr111860.c b/gcc/testsuite/gcc.dg/vect/pr111860.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..36f0774601040418bc6b7f27c9425b2bf93b18cb
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/vect/pr111860.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +
> +int optimize_path_n, optimize_path_d;
> +int *optimize_path_d_0;
> +extern void path_threeOpt( long);
> +void optimize_path() {
> +  int i;
> +  long length;
> +  i = 0;
> +  for (; i <= optimize_path_n; i++)
> +    optimize_path_d = 0;
> +  i = 0;
> +  for (; i < optimize_path_n; i++)
> +    length += optimize_path_d_0[i];
> +  path_threeOpt(length);
> +}
> diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
> index 1f7779b9834c3aef3c6a993fab916224fab03147..fc55278e63f7a48943fdc32c5e207110cf14507e 100644
> --- a/gcc/tree-vect-loop-manip.cc
> +++ b/gcc/tree-vect-loop-manip.cc
> @@ -1626,13 +1626,33 @@ slpeel_tree_duplicate_loop_to_edge_cfg (class loop *loop, edge loop_exit,
>  	  edge temp_e = redirect_edge_and_branch (exit, new_preheader);
>  	  flush_pending_stmts (temp_e);
>  	}
> -
>        /* Record the new SSA names in the cache so that we can skip materializing
>  	 them again when we fill in the rest of the LCSSA variables.  */
>        for (auto phi : new_phis)
>  	{
>  	  tree new_arg = gimple_phi_arg (phi, 0)->def;
>  	  new_phi_args.put (new_arg, gimple_phi_result (phi));

don't you want to skip this as well?

> +
> +	  if (!SSA_VAR_P (new_arg))
> +	    continue;
> +	  /* If the PHI MEM node dominates the loop then we shouldn't create
> +	      a new LC-SSSA PHI for it in the intermediate block.   */
> +	  gimple *def_stmt = SSA_NAME_DEF_STMT (new_arg);
> +	  basic_block def_bb = gimple_bb (def_stmt);
> +	  /* A MEM phi that consitutes a new DEF for the vUSE chain can either
> +	     be a .VDEF or a PHI that operates on MEM.  */
> +	  if (((gimple_vdef (def_stmt) || is_a <gphi *> (def_stmt))
> +		  /* And said definition must not be inside the main loop.  */
> +	       && (!def_bb || !flow_bb_inside_loop_p (loop, def_bb)))
> +	      /* Or we must be a parameter.  In the last two cases we may remove
> +		 a non-MEM PHI node, but since they dominate both loops the
> +		 removal is unlikely to cause trouble as the exits must already
> +		 be using them.  */
> +	      || SSA_NAME_IS_DEFAULT_DEF (new_arg))
> +	    {
> +	      auto gsi = gsi_for_stmt (phi);
> +	      remove_phi_node (&gsi, true);
> +	    }

May I suggest the simpler

          gimple *def;
	  if (virtual_operand_p (new_arg)
              && (SSA_NAME_IS_DEFAULT_DEF (new_arg)
                  || !flow_bb_inside_loop_p (loop,
				gimple_bb (SSA_NAME_DEF_STMT (new_arg))))
	    {
> +           auto gsi = gsi_for_stmt (phi);
> +           remove_phi_node (&gsi, true);
            }

?

OK with that change.

Richard.
diff mbox series

Patch

--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr111860-2.c
@@ -0,0 +1,17 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O -fno-tree-sink -ftree-vectorize" } */
+int buffer_ctrl_ctx_0, buffer_ctrl_p1, buffer_ctrl_cmd;
+
+int
+buffer_ctrl (long ret, int i)
+{
+  switch (buffer_ctrl_cmd)
+    {
+    case 1:
+      buffer_ctrl_ctx_0 = 0;
+      for (; i; i++)
+	if (buffer_ctrl_p1)
+	  ret++;
+    }
+  return ret;
+}
diff --git a/gcc/testsuite/gcc.dg/vect/pr111860-3.c b/gcc/testsuite/gcc.dg/vect/pr111860-3.c
new file mode 100644
index 0000000000000000000000000000000000000000..07f64ffb5318c9d7817d46802d123cc9a2d65ec9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr111860-3.c
@@ -0,0 +1,17 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O -fno-tree-sink -ftree-vectorize" } */
+int buffer_ctrl_ctx_0, buffer_ctrl_p1, buffer_ctrl_cmd;
+
+int
+buffer_ctrl (long ret, int i)
+{
+  switch (buffer_ctrl_cmd)
+    {
+    case 1:
+      buffer_ctrl_ctx_0 = 0;
+      for (; i; i++)
+	if (buffer_ctrl_p1)
+	  ret++;
+    }
+  return ret;
+}
diff --git a/gcc/testsuite/gcc.dg/vect/pr111860.c b/gcc/testsuite/gcc.dg/vect/pr111860.c
new file mode 100644
index 0000000000000000000000000000000000000000..36f0774601040418bc6b7f27c9425b2bf93b18cb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr111860.c
@@ -0,0 +1,16 @@ 
+/* { dg-do compile } */
+
+int optimize_path_n, optimize_path_d;
+int *optimize_path_d_0;
+extern void path_threeOpt( long);
+void optimize_path() {
+  int i;
+  long length;
+  i = 0;
+  for (; i <= optimize_path_n; i++)
+    optimize_path_d = 0;
+  i = 0;
+  for (; i < optimize_path_n; i++)
+    length += optimize_path_d_0[i];
+  path_threeOpt(length);
+}
diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
index 1f7779b9834c3aef3c6a993fab916224fab03147..fc55278e63f7a48943fdc32c5e207110cf14507e 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -1626,13 +1626,33 @@  slpeel_tree_duplicate_loop_to_edge_cfg (class loop *loop, edge loop_exit,
 	  edge temp_e = redirect_edge_and_branch (exit, new_preheader);
 	  flush_pending_stmts (temp_e);
 	}
-
       /* Record the new SSA names in the cache so that we can skip materializing
 	 them again when we fill in the rest of the LCSSA variables.  */
       for (auto phi : new_phis)
 	{
 	  tree new_arg = gimple_phi_arg (phi, 0)->def;
 	  new_phi_args.put (new_arg, gimple_phi_result (phi));
+
+	  if (!SSA_VAR_P (new_arg))
+	    continue;
+	  /* If the PHI MEM node dominates the loop then we shouldn't create
+	      a new LC-SSSA PHI for it in the intermediate block.   */
+	  gimple *def_stmt = SSA_NAME_DEF_STMT (new_arg);
+	  basic_block def_bb = gimple_bb (def_stmt);
+	  /* A MEM phi that consitutes a new DEF for the vUSE chain can either
+	     be a .VDEF or a PHI that operates on MEM.  */
+	  if (((gimple_vdef (def_stmt) || is_a <gphi *> (def_stmt))
+		  /* And said definition must not be inside the main loop.  */
+	       && (!def_bb || !flow_bb_inside_loop_p (loop, def_bb)))
+	      /* Or we must be a parameter.  In the last two cases we may remove
+		 a non-MEM PHI node, but since they dominate both loops the
+		 removal is unlikely to cause trouble as the exits must already
+		 be using them.  */
+	      || SSA_NAME_IS_DEFAULT_DEF (new_arg))
+	    {
+	      auto gsi = gsi_for_stmt (phi);
+	      remove_phi_node (&gsi, true);
+	    }
 	}
 
       /* Copy the current loop LC PHI nodes between the original loop exit