On 6/21/19 2:57 PM, Jan Hubicka wrote:
> This looks like good step (and please stream it in host independent
> way). I suppose all these issues can be done one-by-one.
So there's a working patch for that. However one will see following errors
when using an older compiler or older LTO bytecode:
$ gcc main9.o -flto
lto1: fatal error: bytecode stream in file ‘main9.o’ generated with LTO version
-25480.4493 instead of the expected 9.0
$ gcc main.o
lto1: internal compiler error: compressed stream: data error
To be honest, I would prefer the new .gnu.lto_.meta section.
Richi why is that so ugly?
Martin
>From cbba4d8209bfeed11856baeaa2f82e44d93f4cb7 Mon Sep 17 00:00:00 2001
From: Martin Liska <mli...@suse.cz>
Date: Fri, 21 Jun 2019 15:57:08 +0200
Subject: [PATCH] Come up with ELF LTO section header.
---
gcc/lto-section-in.c | 14 +++++++++++---
gcc/lto-section-out.c | 16 ++++++++++++++--
gcc/lto-streamer-out.c | 12 ++++--------
gcc/lto-streamer.h | 14 +++++++++++---
4 files changed, 40 insertions(+), 16 deletions(-)
diff --git a/gcc/lto-section-in.c b/gcc/lto-section-in.c
index 4cfc0cad4be..28dfb412b67 100644
--- a/gcc/lto-section-in.c
+++ b/gcc/lto-section-in.c
@@ -143,6 +143,17 @@ lto_get_section_data (struct lto_file_decl_data *file_data,
if (data == NULL)
return NULL;
+ /* First check LTO section header. */
+ if (*len < sizeof(lto_section_header))
+ return NULL;
+
+ const lto_section_header *sh = (const lto_section_header *)data;
+ lto_check_version (sh->major_version, sh->minor_version,
+ file_data->file_name);
+
+ data += sizeof (lto_section_header);
+ *len -= sizeof (lto_section_header);
+
/* WPA->ltrans streams are not compressed with exception of function bodies
and variable initializers that has been verbatim copied from earlier
compilations. */
@@ -167,9 +178,6 @@ lto_get_section_data (struct lto_file_decl_data *file_data,
data = buffer.data + header_length;
}
- lto_check_version (((const lto_header *)data)->major_version,
- ((const lto_header *)data)->minor_version,
- file_data->file_name);
return data;
}
diff --git a/gcc/lto-section-out.c b/gcc/lto-section-out.c
index c91e58f0465..9417bc9c174 100644
--- a/gcc/lto-section-out.c
+++ b/gcc/lto-section-out.c
@@ -81,6 +81,19 @@ lto_begin_section (const char *name, bool compress)
compression_stream = lto_start_compression (lto_append_data, NULL);
}
+/* Emit section header with LTO bytecode version and information about used
+ compression. */
+
+void lto_emit_section_header (void)
+{
+ lto_compression compression = RAW;
+ if (compression_stream != NULL)
+ compression = ZLIB;
+
+ lto_section_header header
+ = { LTO_major_version, LTO_minor_version, compression };
+ lto_write_raw_data (&header, sizeof header);
+}
/* End the current output section. */
@@ -285,8 +298,7 @@ lto_destroy_simple_output_block (struct lto_simple_output_block *ob)
/* Write the header which says how to decode the pieces of the
t. */
memset (&header, 0, sizeof (struct lto_simple_header));
- header.major_version = LTO_major_version;
- header.minor_version = LTO_minor_version;
+ lto_emit_section_header ();
header.main_size = ob->main_stream->total_size;
lto_write_data (&header, sizeof header);
diff --git a/gcc/lto-streamer-out.c b/gcc/lto-streamer-out.c
index b1084f4d3c5..42f03ac504e 100644
--- a/gcc/lto-streamer-out.c
+++ b/gcc/lto-streamer-out.c
@@ -1973,8 +1973,7 @@ produce_asm (struct output_block *ob, tree fn)
memset (&header, 0, sizeof (struct lto_function_header));
/* Write the header. */
- header.major_version = LTO_major_version;
- header.minor_version = LTO_minor_version;
+ lto_emit_section_header ();
if (section_type == LTO_section_function_body)
header.cfg_size = ob->cfg_stream->total_size;
@@ -2269,8 +2268,7 @@ lto_output_toplevel_asms (void)
memset (&header, 0, sizeof (header));
/* Write the header. */
- header.major_version = LTO_major_version;
- header.minor_version = LTO_minor_version;
+ lto_emit_section_header ();
header.main_size = ob->main_stream->total_size;
header.string_size = ob->string_stream->total_size;
@@ -2826,8 +2824,7 @@ lto_write_mode_table (void)
memset (&header, 0, sizeof (header));
/* Write the header. */
- header.major_version = LTO_major_version;
- header.minor_version = LTO_minor_version;
+ lto_emit_section_header ();
header.main_size = ob->main_stream->total_size;
header.string_size = ob->string_stream->total_size;
@@ -2899,8 +2896,7 @@ produce_asm_for_decls (void)
lto_output_decl_state_streams (ob, fn_out_state);
}
- header.major_version = LTO_major_version;
- header.minor_version = LTO_minor_version;
+ lto_emit_section_header ();
/* Currently not used. This field would allow us to preallocate
the globals vector, so that it need not be resized as it is extended. */
diff --git a/gcc/lto-streamer.h b/gcc/lto-streamer.h
index d087cba9bf0..8fc1ac01356 100644
--- a/gcc/lto-streamer.h
+++ b/gcc/lto-streamer.h
@@ -378,18 +378,25 @@ public:
unsigned int len;
};
+enum lto_compression
+{
+ RAW,
+ ZLIB,
+ ZSTD
+};
/* The is the first part of the record for a function or constructor
in the .o file. */
-struct lto_header
+struct lto_section_header
{
int16_t major_version;
- int16_t minor_version;
+ int16_t minor_version : 14;
+ lto_compression compression : 2;
};
/* The is the first part of the record in an LTO file for many of the
IPA passes. */
-struct lto_simple_header : lto_header
+struct lto_simple_header
{
/* Size of main gimple body of function. */
int32_t main_size;
@@ -784,6 +791,7 @@ extern void lto_value_range_error (const char *,
/* In lto-section-out.c */
extern void lto_begin_section (const char *, bool);
+extern void lto_emit_section_header (void);
extern void lto_end_section (void);
extern void lto_write_data (const void *, unsigned int);
extern void lto_write_raw_data (const void *, unsigned int);
--
2.21.0
