Re: [PATCH] Set discriminators for call stmts on the same line within the same basic block

[Eugene Rozenfeld <Eugene.Rozenfeld@microsoft.com>]

Thank you for the review Jason.

I fixed formatting and updated the commit description:
----------------------------

Call statements are possible split points of a basic block so they may end up
in different basic blocks by the time pass_ipa_auto_profile executes.

This change will also simplify call site lookups since now location with discriminator
will uniquely identify the call site (no callee function name is needed).

This change is based on commit 1e6c4a7a8fb8e20545bb9f9032d3854f3f794c18
by Dehao Chen in vendors/google/heads/gcc-4_8.

Tested on x86_64-pc-linux-gnu.

gcc/ChangeLog:
	* tree-cfg.cc (assign_discriminators): Set discriminators for call stmts
	on the same line within the same basic block.
---
 gcc/tree-cfg.cc | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index ade66c54499..f6a465f4c91 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -1203,8 +1203,40 @@ assign_discriminators (void)
     {
       edge e;
       edge_iterator ei;
+      gimple_stmt_iterator gsi;
       gimple *last = last_stmt (bb);
       location_t locus = last ? gimple_location (last) : UNKNOWN_LOCATION;
+      location_t curr_locus = UNKNOWN_LOCATION;
+      int curr_discr = 0;
+
+      /* Traverse the basic block, if two function calls within a basic block
+	are mapped to the same line, assign a new discriminator because a call
+	stmt could be a split point of a basic block.  */
+      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+	{
+	  gimple *stmt = gsi_stmt (gsi);
+	  expanded_location curr_locus_e;
+	  if (curr_locus == UNKNOWN_LOCATION)
+	    {
+	      curr_locus = gimple_location (stmt);
+	      curr_locus_e = expand_location (curr_locus);
+	    }
+	  else if (!same_line_p (curr_locus, &curr_locus_e, gimple_location (stmt)))
+	    {
+	      curr_locus = gimple_location (stmt);
+	      curr_locus_e = expand_location (curr_locus);
+	      curr_discr = 0;
+	    }
+	  else if (curr_discr != 0)
+	    {
+	      location_t loc = gimple_location (stmt);
+	      location_t dloc = location_with_discriminator (loc, curr_discr);
+	      gimple_set_location (stmt, dloc);
+	    }
+	  /* Allocate a new discriminator for CALL stmt.  */
+	  if (gimple_code (stmt) == GIMPLE_CALL)
+	    curr_discr = next_discriminator_for_locus (curr_locus);
+	}
 
       if (locus == UNKNOWN_LOCATION)
 	continue;
-- 
2.25.1

-----Original Message-----
From: Jason Merrill <jason@redhat.com> 
Sent: Tuesday, October 04, 2022 3:21 PM
To: Eugene Rozenfeld <Eugene.Rozenfeld@microsoft.com>; gcc-patches@gcc.gnu.org
Subject: [EXTERNAL] Re: [PATCH] Set discriminators for call stmts on the same line within the same basic block

On 10/3/22 02:08, Eugene Rozenfeld wrote:
> This change is based on commit 
> 1e6c4a7a8fb8e20545bb9f9032d3854f3f794c18
> by Dehao Chen in vendors/google/heads/gcc-4_8.
> 
> Tested on x86_64-pc-linux-gnu.

Brief rationale for the change?

> gcc/ChangeLog:
>          * tree-cfg.cc (assign_discriminators): Set discriminators for call stmts
>          on the same line within the same basic block.
> ---
>   gcc/tree-cfg.cc | 31 +++++++++++++++++++++++++++++++
>   1 file changed, 31 insertions(+)
> 
> diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc index 
> ade66c54499..8e2a3a5f6c6 100644
> --- a/gcc/tree-cfg.cc
> +++ b/gcc/tree-cfg.cc
> @@ -1203,8 +1203,39 @@ assign_discriminators (void)
>       {
>         edge e;
>         edge_iterator ei;
> +      gimple_stmt_iterator gsi;
>         gimple *last = last_stmt (bb);
>         location_t locus = last ? gimple_location (last) : 
> UNKNOWN_LOCATION;
> +      location_t curr_locus = UNKNOWN_LOCATION;
> +      int curr_discr = 0;
> +
> +      /* Traverse the basic block, if two function calls within a basic block
> +       are mapped to the same line, assign a new discriminator because a call
> +       stmt could be a split point of a basic block.  */
> +      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
> +       {
> +         gimple *stmt = gsi_stmt (gsi);
> +         expanded_location curr_locus_e;
> +         if (curr_locus == UNKNOWN_LOCATION)
> +           {
> +             curr_locus = gimple_location (stmt);
> +             curr_locus_e = expand_location (curr_locus);
> +           }
> +         else if (!same_line_p (curr_locus, &curr_locus_e, gimple_location (stmt)))
> +           {
> +             curr_locus = gimple_location (stmt);
> +             curr_locus_e = expand_location (curr_locus);
> +             curr_discr = 0;
> +           }
> +         else if (curr_discr != 0)
> +           {
> +             gimple_set_location (stmt, location_with_discriminator (
> +                 gimple_location (stmt), curr_discr));

This indentation is wonky, with an open paren at the end of the line; I'd suggest reformatting to

>              location_t dloc = (location_with_discriminator >                                 (gimple_location (stmt), 
curr_discr));>              gimple_set_location (stmt, dloc);

Jason