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author | Björn Gustavsson <[email protected]> | 2016-05-31 22:49:42 +0200 |
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committer | Björn Gustavsson <[email protected]> | 2016-06-01 10:09:20 +0200 |
commit | aab1db16d0a732823fa9e2964c6a52b109c61742 (patch) | |
tree | 3ba6111af79e023fc1476dc815a14f9f95faa69a /lib/compiler/src/sys_core_fold.erl | |
parent | ac927e00f82b3df962abe082393f45197de49156 (diff) | |
download | otp-aab1db16d0a732823fa9e2964c6a52b109c61742.tar.gz otp-aab1db16d0a732823fa9e2964c6a52b109c61742.tar.bz2 otp-aab1db16d0a732823fa9e2964c6a52b109c61742.zip |
beam_block: Eliminate crash in beam_utils
Somewhat simplified, beam_block would rewrite the target for
the first instruction in this code sequence:
move x(0) => y(1)
gc_bif '+' 1 x(0) => y(0)
move y(1) => x(1)
move nil => x(0)
call 2 local_function/2
The resulting code would be:
move x(0) => x(1) %% Changed target.
gc_bif '+' 1 x(0) => y(0)
move x(1) => y(1) %% Operands swapped (see 02d6135813).
move nil => x(0)
call 2 local_function/2
The resulting code is not safe because the x(1) will be killed
by the gc_bif instruction.
7a47b20c3a cleaned up move optimizations and would reject the
optimization if the target was an X register and an allocating
instruction was found. To avoid this bug, the optimization must be
rejected even if the target is a Y register.
Diffstat (limited to 'lib/compiler/src/sys_core_fold.erl')
0 files changed, 0 insertions, 0 deletions