Streamer: Fix out of range memory access of machine mode

We extend the machine mode from 8 to 16 bits already. But there still
one placing missing from the streamer. It has one hard coded array
for the machine code like size 256.

In the lto pass, we memset the array by MAX_MACHINE_MODE count but the
value of the MAX_MACHINE_MODE will grow as more and more modes are
added. While the machine mode array in tree-streamer still leave 256 as is.

Then, when the MAX_MACHINE_MODE is greater than 256, the memset of
lto_output_init_mode_table will touch the memory out of range unexpected.

This patch would like to take the MAX_MACHINE_MODE as the size of the
array in streamer, to make sure there is no potential unexpected
memory access in future. Meanwhile, this patch also adjust some place
which has MAX_MACHINE_MODE <= 256 assumption.

Care is taken that for offload compilation, we interpret the stream-in
data in terms of the host 'MAX_MACHINE_MODE' ('file_data->mode_bits'),
which very likely is different from the offload device
'MAX_MACHINE_MODE'.

	gcc/
	* lto-streamer-in.cc (lto_input_mode_table): Stream in the mode
	bits for machine mode table.
	* lto-streamer-out.cc (lto_write_mode_table): Stream out the
	HOST machine mode bits.
	* lto-streamer.h (struct lto_file_decl_data): New fields mode_bits.
	* tree-streamer.cc (streamer_mode_table): Take MAX_MACHINE_MODE
	as the table size.
	* tree-streamer.h (streamer_mode_table): Ditto.
	(bp_pack_machine_mode): Take 1 << ceil_log2 (MAX_MACHINE_MODE)
	as the packing limit.
	(bp_unpack_machine_mode): Ditto with 'file_data->mode_bits'.
	gcc/lto/
	* lto-common.cc (lto_file_finalize) [!ACCEL_COMPILER]: Initialize
	'file_data->mode_bits'.

Signed-off-by: Pan Li <pan2.li@intel.com>
Co-authored-by: Thomas Schwinge <thomas@codesourcery.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/gcc/lto/lto-common.cc b/gcc/lto/lto-common.cc
index cdb37c8..703e665 100644
--- a/gcc/lto/lto-common.cc
+++ b/gcc/lto/lto-common.cc
@@ -2278,6 +2278,7 @@ lto_file_finalize (struct lto_file_decl_data *file_data, lto_file *file,
   lto_input_mode_table (file_data);
 #else
   file_data->mode_table = lto_mode_identity_table;
+  file_data->mode_bits = ceil_log2 (MAX_MACHINE_MODE);
 #endif
 
   data = lto_get_summary_section_data (file_data, LTO_section_decls, &len);