[PATCH 2/7 v2] lto: Remove random_seed from section name.

[Michal Jires]

This patch removes suffixes from section names during LTO linking.

These suffixes were originally added for ld -r to work (PR lto/44992).
They were added to all LTO object files, but are only useful before WPA.
After that they waste space, and if kept random, make LTO caching impossible.

Bootstrapped/regtested on x86_64-pc-linux-gnu

gcc/ChangeLog:

        * lto-streamer.cc (lto_get_section_name): Remove suffixes after WPA.

gcc/lto/ChangeLog:

        * lto-common.cc (lto_section_with_id): Dont load suffix during LTRANS.
---
 gcc/lto-streamer.cc   | 11 +++++++++--
 gcc/lto/lto-common.cc |  7 +++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/gcc/lto-streamer.cc b/gcc/lto-streamer.cc
index 8032bbf7108..61b5f8ed4dc 100644
--- a/gcc/lto-streamer.cc
+++ b/gcc/lto-streamer.cc
@@ -132,11 +132,18 @@ lto_get_section_name (int section_type, const char *name,
      doesn't confuse the reader with merged sections.
 
      For options don't add a ID, the option reader cannot deal with them
-     and merging should be ok here. */
-  if (section_type == LTO_section_opts)
+     and merging should be ok here.
+
+     LTRANS files (output of wpa, input and output of ltrans) are handled
+     directly inside of linker/lto-wrapper, so name uniqueness for external
+     tools is not needed.
+     Randomness would inhibit incremental LTO.  */
+  if (section_type == LTO_section_opts || flag_ltrans)
     strcpy (post, "");
   else if (f != NULL) 
     sprintf (post, "." HOST_WIDE_INT_PRINT_HEX_PURE, f->id);
+  else if (flag_wpa)
+    strcpy (post, "");
   else
     sprintf (post, "." HOST_WIDE_INT_PRINT_HEX_PURE, get_random_seed (false)); 
   char *res = concat (section_name_prefix, sep, add, post, NULL);
diff --git a/gcc/lto/lto-common.cc b/gcc/lto/lto-common.cc
index 11e7d63f1be..44aeeddf46f 100644
--- a/gcc/lto/lto-common.cc
+++ b/gcc/lto/lto-common.cc
@@ -2174,6 +2174,13 @@ lto_section_with_id (const char *name, unsigned 
HOST_WIDE_INT *id)
 
   if (strncmp (name, section_name_prefix, strlen (section_name_prefix)))
     return 0;
+
+  if (flag_ltrans)
+    {
+      *id = 0;
+      return 1;
+    }
+
   s = strrchr (name, '.');
   if (!s)
     return 0;
-- 
2.43.0