Erik Eckstein bf496aa4f6 Optimizer: add simplification for fix_lifetime ...

Canonicalize a `fix_lifetime` from an address to a `load` + `fix_lifetime`:
```
   %1 = alloc_stack $T
   ...
   fix_lifetime %1
```
->
```
   %1 = alloc_stack $T
   ...
   %2 = load %1
   fix_lifetime %2
```

This transformation is done for `alloc_stack` and `store_borrow` (which always has an `alloc_stack` operand).
The benefit of this transformation is that it enables other optimizations, like mem2reg.

This peephole optimization was already done in SILCombine, but it didn't handle store_borrow.
A good opportunity to make an instruction simplification out of it.

This is part of fixing regressions when enabling OSSA modules:
rdar://140229560

2024-12-13 12:06:20 +01:00

1.8 KiB

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