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Rollup of 4 pull requests - #71876
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Dylan-DPC-zz wants to merge 8 commits into
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- Documented rationale of current solution - Polished documentation
When panic != unwind, `nounwind` is added to all functions for a target. This can cause issues when a panic happens with RUST_BACKTRACE=1, as there needs to be a way to reconstruct the backtrace. There are three possible sources of this information: forcing frame pointers (for which an option exists already), debug info (for which an option exists), or unwind tables. Especially for embedded devices, forcing frame pointers can have code size overheads (RISC-V sees ~10% overheads, ARM sees ~2-3% overheads). In code, it can be the case that debug info is not kept, so it is useful to provide this third option, unwind tables, that users can use to reconstruct the call stack. Reconstructing this stack is harder than with frame pointers, but it is still possible. This commit adds a compiler option which allows a user to force the addition of unwind tables. Unwind tables cannot be disabled on targets that require them for correctness, or when using `-C panic=unwind`.
…na-kruppe Add Option to Force Unwind Tables When panic != unwind, `nounwind` is added to all functions for a target. This can cause issues when a panic happens with RUST_BACKTRACE=1, as there needs to be a way to reconstruct the backtrace. There are three possible sources of this information: forcing frame pointers (for which an option exists already), debug info (for which an option exists), or unwind tables. Especially for embedded devices, forcing frame pointers can have code size overheads (RISC-V sees ~10% overheads, ARM sees ~2-3% overheads). In production code, it can be the case that debug info is not kept, so it is useful to provide this third option, unwind tables, that users can use to reconstruct the call stack. Reconstructing this stack is harder than with frame pointers, but it is still possible. --- This came up in discussion on rust-lang#69890, and turned out to be a fairly simple addition. r? @hanna-kruppe
…wesleywiser Added MIR constant propagation of Scalars into function call arguments Now for the function call arguments! Caveats: 1. It's only being enabled at `mir-opt-2` or higher, because currently codegen gives performance regressions with this optimization. 2. Only propagates Scalars. Tuples and references (references are `Indirect`, right??) are not being propagated into as of this PR. 3. Maybe more tests would be nice? 4. I need (shamefully) to ask @wesleywiser to write in his words (or explain to me, and then I can write it down) why we want to ignore propagation into `ScalarPairs` and `Indirect` arguments. r? @wesleywiser
doc: misc rustdoc things
Do not try to find binop method on RHS `TyErr` Fixrust-lang#71798.
Dylan-DPC-zz
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May 4, 2020
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@bors r+ rollup=never p=4 |
bors
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May 4, 2020
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📌 Commit cbae34c has been approved by |
bors
commented
May 4, 2020
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⌛ Testing commit cbae34c with merge 1b61dd7a782bf38ab2aaddb6100e7b4d2319c940... |
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Successful merges:
TyErr#71810 (Do not try to find binop method on RHSTyErr)Failed merges:
r? @ghost