diff mbox series

Document 'pass_postreload' vs. 'pass_late_compilation' (was: The nvptx port [4/11+] Post-RA pipeline)

Message ID 87a5j5t8b7.fsf@euler.schwinge.ddns.net
State New
Headers show
Series Document 'pass_postreload' vs. 'pass_late_compilation' (was: The nvptx port [4/11+] Post-RA pipeline) | expand

Commit Message

Thomas Schwinge June 28, 2024, 3:07 p.m. UTC 
Hi!

Before we start looking into enabling certain 'pass_postreload' passes
for nvptx, as we've been discussing in
<https://inbox.sourceware.org/007a01dac921$82d0d9c0$88728d40$@nextmovesoftware.com>
"nvptx vs. [PATCH] Add a late-combine pass [PR106594]", let's first
document the (not quite obvious) status quo:

On 2014-10-20T16:24:43+0200, Bernd Schmidt <bernds@codesourcery.com> wrote:
> This stops most of the post-regalloc passes to be run if the target 
> doesn't want register allocation. I'd previously moved them all out of 
> postreload to the toplevel, but Jakub (I think) pointed out that the 
> idea is not to run them to avoid crashes if reload fails e.g. for an 
> invalid asm. So I've made a new container pass.

OK to push "Document 'pass_postreload' vs. 'pass_late_compilation'", see
attached?


Grüße
 Thomas


> A later patch will make thread_prologue_and_epilogue_insns callable from 
> the backend.
>
>
> Bernd
>
> 	gcc/
> 	* passes.def (pass_compute_alignments, pass_duplicate_computed_gotos,
> 	pass_variable_tracking, pass_free_cfg, pass_machine_reorg,
> 	pass_cleanup_barriers, pass_delay_slots,
> 	pass_split_for_shorten_branches, pass_convert_to_eh_region_ranges,
> 	pass_shorten_branches, pass_est_nothrow_function_flags,
> 	pass_dwarf2_frame, pass_final): Move outside of pass_postreload and
> 	into pass_late_compilation.
> 	(pass_late_compilation): Add.
> 	* passes.c (pass_data_late_compilation, pass_late_compilation,
> 	make_pass_late_compilation): New.
> 	* timevar.def (TV_LATE_COMPILATION): New.
>
> ------------------------------------------------------------------------
> Index: gcc/passes.def
> ===================================================================
> --- gcc/passes.def.orig
> +++ gcc/passes.def
> @@ -415,6 +415,9 @@ along with GCC; see the file COPYING3.
>  	      NEXT_PASS (pass_split_before_regstack);
>  	      NEXT_PASS (pass_stack_regs_run);
>  	  POP_INSERT_PASSES ()
> +      POP_INSERT_PASSES ()
> +      NEXT_PASS (pass_late_compilation);
> +      PUSH_INSERT_PASSES_WITHIN (pass_late_compilation)
>  	  NEXT_PASS (pass_compute_alignments);
>  	  NEXT_PASS (pass_variable_tracking);
>  	  NEXT_PASS (pass_free_cfg);
> Index: gcc/passes.c
> ===================================================================
> --- gcc/passes.c.orig
> +++ gcc/passes.c
> @@ -569,6 +569,44 @@ make_pass_postreload (gcc::context *ctxt
>    return new pass_postreload (ctxt);
>  }
>  
> +namespace {
> +
> +const pass_data pass_data_late_compilation =
> +{
> +  RTL_PASS, /* type */
> +  "*all-late_compilation", /* name */
> +  OPTGROUP_NONE, /* optinfo_flags */
> +  TV_LATE_COMPILATION, /* tv_id */
> +  PROP_rtl, /* properties_required */
> +  0, /* properties_provided */
> +  0, /* properties_destroyed */
> +  0, /* todo_flags_start */
> +  0, /* todo_flags_finish */
> +};
> +
> +class pass_late_compilation : public rtl_opt_pass
> +{
> +public:
> +  pass_late_compilation (gcc::context *ctxt)
> +    : rtl_opt_pass (pass_data_late_compilation, ctxt)
> +  {}
> +
> +  /* opt_pass methods: */
> +  virtual bool gate (function *)
> +  {
> +    return reload_completed || targetm.no_register_allocation;
> +  }
> +
> +}; // class pass_late_compilation
> +
> +} // anon namespace
> +
> +static rtl_opt_pass *
> +make_pass_late_compilation (gcc::context *ctxt)
> +{
> +  return new pass_late_compilation (ctxt);
> +}
> +
>  
>  
>  /* Set the static pass number of pass PASS to ID and record that
> Index: gcc/timevar.def
> ===================================================================
> --- gcc/timevar.def.orig
> +++ gcc/timevar.def
> @@ -270,6 +270,7 @@ DEFTIMEVAR (TV_EARLY_LOCAL	     , "early
>  DEFTIMEVAR (TV_OPTIMIZE		     , "unaccounted optimizations")
>  DEFTIMEVAR (TV_REST_OF_COMPILATION   , "rest of compilation")
>  DEFTIMEVAR (TV_POSTRELOAD	     , "unaccounted post reload")
> +DEFTIMEVAR (TV_LATE_COMPILATION	     , "unaccounted late compilation")
>  DEFTIMEVAR (TV_REMOVE_UNUSED	     , "remove unused locals")
>  DEFTIMEVAR (TV_ADDRESS_TAKEN	     , "address taken")
>  DEFTIMEVAR (TV_TODO		     , "unaccounted todo")
diff mbox series

Patch

From 7f708dd9774773e704cb06b7a6f296927f9057df Mon Sep 17 00:00:00 2001
From: Thomas Schwinge <tschwinge@baylibre.com>
Date: Fri, 28 Jun 2024 16:04:18 +0200
Subject: [PATCH] Document 'pass_postreload' vs. 'pass_late_compilation'

See Subversion r217124 (Git commit 433e4164339f18d0b8798968444a56b681b5232c)
"Reorganize post-ra pipeline for targets without register allocation".

	gcc/
	* passes.cc: Document 'pass_postreload' vs. 'pass_late_compilation'.
	* passes.def: Likewise.
---
 gcc/passes.cc  | 14 +++++++++++++-
 gcc/passes.def |  3 +++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/gcc/passes.cc b/gcc/passes.cc
index d3648a24b58..e444b462113 100644
--- a/gcc/passes.cc
+++ b/gcc/passes.cc
@@ -660,6 +660,10 @@  make_pass_rest_of_compilation (gcc::context *ctxt)
 
 namespace {
 
+/* A container pass (only) for '!targetm.no_register_allocation' targets, for
+   passes to run if reload completed (..., but not run them if it failed, for
+   example for an invalid 'asm').  See also 'pass_late_compilation'.  */
+
 const pass_data pass_data_postreload =
 {
   RTL_PASS, /* type */
@@ -681,7 +685,12 @@  public:
   {}
 
   /* opt_pass methods: */
-  bool gate (function *) final override { return reload_completed; }
+  bool gate (function *) final override
+  {
+    if (reload_completed)
+      gcc_checking_assert (!targetm.no_register_allocation);
+    return reload_completed;
+  }
 
 }; // class pass_postreload
 
@@ -695,6 +704,9 @@  make_pass_postreload (gcc::context *ctxt)
 
 namespace {
 
+/* A container pass like 'pass_postreload', but for passes to run also for
+   'targetm.no_register_allocation' targets.  */
+
 const pass_data pass_data_late_compilation =
 {
   RTL_PASS, /* type */
diff --git a/gcc/passes.def b/gcc/passes.def
index 61ca210822a..72198bc4c4e 100644
--- a/gcc/passes.def
+++ b/gcc/passes.def
@@ -507,6 +507,9 @@  along with GCC; see the file COPYING3.  If not see
       NEXT_PASS (pass_early_remat);
       NEXT_PASS (pass_ira);
       NEXT_PASS (pass_reload);
+      /* In the following, some passes are tied to 'pass_postreload' and others
+	 to 'pass_late_compilation'.  The difference is that the latter also
+	 run for 'targetm.no_register_allocation' targets.  */
       NEXT_PASS (pass_postreload);
       PUSH_INSERT_PASSES_WITHIN (pass_postreload)
 	  NEXT_PASS (pass_postreload_cse);
-- 
2.34.1