[PATCH] c: Fix compile time hog in c_genericize [PR107127]

[PATCH] c: Fix compile time hog in c_genericize [PR107127]

[Jakub Jelinek]

Hi!

The complex multiplications result in deeply nested set of many SAVE_EXPRs,
which takes even on fast machines over 5 minutes to walk.
This patch fixes that by using walk_tree_without_duplicates where it is
instant.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2022-11-23  Andrew Pinski  <apinski@marvell.com>
	    Jakub Jelinek  <jakub@redhat.com>

	PR c/107127
	* c-gimplify.cc (c_genericize): Use walk_tree_without_duplicates
	instead of walk_tree for c_genericize_control_r.

	* gcc.dg/pr107127.c: New test.

--- gcc/c-family/c-gimplify.cc.jj	2022-08-12 13:39:59.229218070 +0200
+++ gcc/c-family/c-gimplify.cc	2022-11-22 11:48:39.977263700 +0100
@@ -572,8 +572,8 @@ c_genericize (tree fndecl)
       bc_state_t save_state;
       push_cfun (DECL_STRUCT_FUNCTION (fndecl));
       save_bc_state (&save_state);
-      walk_tree (&DECL_SAVED_TREE (fndecl), c_genericize_control_r,
-		 NULL, NULL);
+      walk_tree_without_duplicates (&DECL_SAVED_TREE (fndecl),
+				    c_genericize_control_r, NULL);
       restore_bc_state (&save_state);
       pop_cfun ();
     }
--- gcc/testsuite/gcc.dg/pr107127.c.jj	2022-11-22 11:56:20.798454526 +0100
+++ gcc/testsuite/gcc.dg/pr107127.c	2022-11-22 11:56:06.224669767 +0100
@@ -0,0 +1,12 @@
+/* PR c/107127 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+int *v;
+
+_Complex double
+foo (_Complex double a, double b, double c)
+{
+  return v[0] / ((((c * (0 - 0 / a + 699.0 + 7.05 - 286.0 - +-4.65 + 1.57 + 0) * 0.1 - 3.28 + 4.22 + 0.1)) * b + 5.06)
+		 * 1.23 * 8.0 * 12.0 * 16.0 * 2.0 * 2.0 * 0.25 * 0.125 * 18.2 * -15.25 * 0.0001
+		 * 42.0 * 0.012 - 8.45 + 0 + 88.0 + 6.96 + 867.0 + 9.10 - 7.04 * -1.0);
+}

	Jakub

Re: [PATCH] c: Fix compile time hog in c_genericize [PR107127]

[Joseph Myers]

On Wed, 23 Nov 2022, Jakub Jelinek via Gcc-patches wrote:

> Hi!
> 
> The complex multiplications result in deeply nested set of many SAVE_EXPRs,
> which takes even on fast machines over 5 minutes to walk.
> This patch fixes that by using walk_tree_without_duplicates where it is
> instant.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> 
> 2022-11-23  Andrew Pinski  <apinski@marvell.com>
> 	    Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR c/107127
> 	* c-gimplify.cc (c_genericize): Use walk_tree_without_duplicates
> 	instead of walk_tree for c_genericize_control_r.
> 
> 	* gcc.dg/pr107127.c: New test.

OK.

-- 
Joseph S. Myers
joseph@codesourcery.com