[Inliner] Fix stack nesting when lowering OSSA. #63980
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Previously, there was an -Xllvm option to verify after all inlining to a particlar caller. That makes it a chore to track down which apply's inlining resulted in invalid code. Here, a new option is added that verifies after each run of the inliner.
Now that in OSSA `partial_apply [on_stack]`s are represented as owned values rather than stack locations, it is possible for their destroys to violate stack discipline. A direct lowering of the instructions to non-OSSA would violate stack nesting. Previously, when inlining, it was assumed that non-coroutine callees maintained stack discipline. And, when inlining an OSSA function into a non-OSSA function, OSSA instructions were lowered directly. The result was that stack discipline could be violated. Here, when inlining a function in OSSA form into a function lowered out of OSSA form, stack nesting is fixed up.
Now that in OSSA `partial_apply [on_stack]`s are represented as owned values rather than stack locations, it is possible for their destroys to violate stack discipline. A direct lowering of the instructions to non-OSSA would violate stack nesting. Previously, when inlining, it was assumed that non-coroutine callees maintained stack discipline. And, when inlining an OSSA function into a non-OSSA function, OSSA instructions were lowered directly. The result was that stack discipline could be violated. Here, when inlining a function in OSSA form into a function lowered out of OSSA form, stack nesting is fixed up.
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@swift-ci please test |
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@swift-ci please clean test macOS platform |
meg-gupta
reviewed
Mar 1, 2023
meg-gupta
requested changes
Mar 1, 2023
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@nate-chandler CSE calls into inline helper - https://github.com/apple/swift/blob/78749d8d00e5e7fa8c82b6235a10e22c65b01098/lib/SILOptimizer/Transforms/CSE.cpp#L791 You may want to move the stack nest fixup to |
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@meg-gupta Thanks for pointing that out. CSE will need to fixup nesting in this case. We don't want to move it into inlineFullApply because nesting shouldn't be fixed up multiple times when multiple callees are inlined. I'm adding a similar call there and also to the other call to inlineFullApply. |
meg-gupta
approved these changes
Mar 1, 2023
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@meg-gupta The CSE fix is here: #64005 . |
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@meg-gupta The fix for the last call to inlineFullApply is here: #64013 . |
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Now that in OSSA
partial_apply [on_stack]s are represented as owned values rather than stack locations, it is possible for their destroys to violate stack discipline. A direct lowering of the instructions to non-OSSA would violate stack nesting.Previously, when inlining, it was assumed that non-coroutine callees maintained stack discipline. And, when inlining an OSSA function into a non-OSSA function, OSSA instructions were lowered directly. The result was that stack discipline could be violated.
Here, when inlining a function in OSSA form into a function lowered out of OSSA form, stack nesting is fixed up.