about summary refs log tree commit diff
path: root/compiler/rustc_llvm/llvm-wrapper
diff options
context:
space:
mode:
authorest31 <MTest31@outlook.com>2022-10-20 09:50:32 +0200
committerest31 <MTest31@outlook.com>2022-12-03 23:32:08 +0100
commit8cf521d80e9057211629e92aff059dc9770c20bd (patch)
treef05da93100e7ff26c9140770b159b34b7efbff10 /compiler/rustc_llvm/llvm-wrapper
parentcab4fd678c5b148a330f2bf255bf28a67dfea0fc (diff)
downloadrust-8cf521d80e9057211629e92aff059dc9770c20bd.tar.gz
rust-8cf521d80e9057211629e92aff059dc9770c20bd.zip
Remove drop order twist of && and || and make them associative
Previously a short circuiting && chain would drop the
first element after all the other elements, and otherwise
follow evaluation order, so code like:

f(1).g() && f(2).g() && f(3).g() && f(4).g()

would drop the temporaries in the order 2,3,4,1. This made
&& and || non-associative regarding drop order, so
adding ()'s to the expression would change drop order:

f(1).g() && (f(2).g() && f(3).g()) && f(4).g()

for example would drop in the order 3,2,4,1.

As, except for the bool result, there is no data returned
by the sub-expressions of the short circuiting binops,
we can safely discard of any temporaries created by the
sub-expr. Previously, code was already putting the rhs's
into terminating scopes, but missed it for the lhs's.

This commit addresses this "twist". In the expression,
we now also put the lhs into a terminating scope.
The drop order for the above expressions is 1,2,3,4
now.
Diffstat (limited to 'compiler/rustc_llvm/llvm-wrapper')
0 files changed, 0 insertions, 0 deletions