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Michael found a bug where some copies
from registers to memory in the arm64
abi clobber the stack. The test case
is:
type :T = { w }
function w $f() {
@start
%p =:T call $g()
%x =w loadw %p
ret %x
}
qbe will write 4 bytes out of bounds
when pulling the result struct from
its register. The same bug can be
observed if :T's definition is {w 3};
in this case qbe writes 16 bytes in
a slot of 12 bytes.
This patch changes stkblob() to use
the rounded argument size if it is
going to be restored from registers.
Relatedly, mem->reg loads for structs
with size < 16 and != 8, are treated
a bit sloppily both in the arm64 and
in the sysv abis. That is much less
harmful than the present bug.
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| .. | ||
| abi.c | ||
| all.h | ||
| emit.c | ||
| isel.c | ||
| targ.c | ||