Disable optimizations based on lifetime intrinsics #3336
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It does not handle loops correctly i.e it moves the lifetime.start
intrinsic into a loop rendering the stack object as not alive for part
of the loop.
```
entry:
%obj = alloca i8
lifetime.start(%obj)
br loop
loop:
coro.suspend()
escape(%obj)
cond_br %cond, label %exit, label loop
br loop
exit:
lifetime.end(%obj
```
After sinking:
```
entry:
%obj = alloca i8
br loop
loop:
coro.suspend()
lifetime.start(%obj)
escape(%obj)
cond_br %cond, label %exit, label loop
br loop
exit:
lifetime.end(%obj
```
rdar://83411917
Differential Revision: https://reviews.llvm.org/D110953
…Retcon Infinite loops can lead to an IR representation where the lifetime.end intrinsice is missing. The code to do lifetime based optimization then fails to see that an address escapes (is life) accross a supspend. Eventually, we could detect such situations and disable it under more narrow circumstances. For now, do the correct thing. rdar://83635953 Differential Revision: https://reviews.llvm.org/D110949
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Lifetime sinking is broken because it ignores initializations via back-edges.
And optimizations baased on the lifetime intrinsic is broken because it ignores certain escapes.
rdar://83411917
rdar://83635953