fdo-mirrors/mesa
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/mesa/mesa.git synced 2026-05-05 09:38:07 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions 2

intel/ir: Fix invalid type aliasing with undefined behavior in test_eu_compact.

Browse source 
test_fuzz_compact_instruction() was attempting to modify the uint64_t
data array of a brw_inst through a pointer to uint32_t, which has
undefined behavior.  This was causing the test_eu_compact unit test to
fail mysteriously for me on GCC 7 with some additional
harmless-looking changes I had applied to my tree, which happened to
affect the order instructions are emitted by GCC causing the bit
twiddling to be done after the clear_pad_bits() call which is supposed
to overwrite the same data through a pointer of different type,
leading to data corruption.  A similar failure has been reported by
Vinson Lee on the master branch built with GCC 8.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105052
Tested-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>
This commit is contained in:
Francisco Jerez 2018-01-26 11:48:02 -08:00
parent 69b4a9d21d
commit cb309d27c5
1 changed files with 3 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
src/intel/compiler/test_eu_compact.cpp
View file

@ -149,13 +149,13 @@ test_fuzz_compact_instruction(struct brw_codegen *p, brw_inst src)
for (int bit1 = 0; bit1 < 128; bit1++) {
brw_inst instr = src;
uint32_t *bits = (uint32_t *)&instr;
uint64_t *bits = instr.data;
if (skip_bit(p->devinfo, &src, bit1))
continue;
bits[bit0 / 32] ^= (1 << (bit0 & 31));
bits[bit1 / 32] ^= (1 << (bit1 & 31));
bits[bit0 / 64] ^= (1ull << (bit0 & 63));
bits[bit1 / 64] ^= (1ull << (bit1 & 63));
clear_pad_bits(p->devinfo, &instr);