nonmoving: Drop redundant write barrier on stack underflow

Authored by bgamari on Sun, Nov 17, 10:51 AM.

Description

nonmoving: Drop redundant write barrier on stack underflow

Previously we would push stack-carried return values to the new stack on
a stack overflow. While the precise reasoning for this barrier is
unfortunately lost to history, in hindsight I suspect it was prompted by
a missing barrier elsewhere (that has been since fixed).

Moreover, there the redundant barrier is actively harmful: the stack may
contain non-pointer values; blindly pushing these to the mark queue will
result in a crash. This is precisely what happened in the stack003
test. However, because of a (now fixed) deficiency in the test this
crash did not trigger on amd64.

Details

Committed
Marge Bot <ben+marge-bot@smart-cactus.org>Tue, Nov 19, 10:57 AM
Parents
rGHCa7571a74df15: testsuite: Increase width of stack003 test
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