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author | Björn Gustavsson <[email protected]> | 2015-10-05 06:43:12 +0200 |
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committer | Björn Gustavsson <[email protected]> | 2015-10-05 12:47:55 +0200 |
commit | 76bb9f0e9a0b36ea7c9720c2bf90f6b52a4eabf8 (patch) | |
tree | 47e29acaeafb5025531d8736ffb7ded30cf678a3 /bootstrap/lib/compiler | |
parent | 7dd616c1832c54370be7f796a4b6578a8d9aedd9 (diff) | |
download | otp-76bb9f0e9a0b36ea7c9720c2bf90f6b52a4eabf8.tar.gz otp-76bb9f0e9a0b36ea7c9720c2bf90f6b52a4eabf8.tar.bz2 otp-76bb9f0e9a0b36ea7c9720c2bf90f6b52a4eabf8.zip |
beam_reorder: Eliminate compiler crash
c288ab87 added beam_reorder to move get_tuple_element instructions.
Compiling code such as the following would crash the compiler:
alloc(_U1, _U2, R) ->
V = R#alloc.version,
Res = id(V),
_ = id(0),
Res.
The crash would occur because the following two instructions:
{get_tuple_element,{x,2},1,{x,1}}.
{allocate_zero,1,2}.
were swapped and rewritten to:
{allocate_zero,1,1}.
{get_tuple_element,{x,2},1,{x,1}}.
That transformation is not safe because the allocate_zero instruction
would kill {x,2}, which is the register that is holding the reference
to the tuple. Only do the transformation when the tuple reference is
in an x register with a lower number than the destination register.
Diffstat (limited to 'bootstrap/lib/compiler')
0 files changed, 0 insertions, 0 deletions