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Add an error for inline assembly which are non-volatile without any outputs #46026

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Zoxc opened this issue Nov 16, 2017 · 2 comments
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Add an error for inline assembly which are non-volatile without any outputs #46026

Zoxc opened this issue Nov 16, 2017 · 2 comments
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A-inline-assembly Area: Inline assembly (`asm!(…)`) C-feature-request Category: A feature request, i.e: not implemented / a PR.

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@Zoxc
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Zoxc commented Nov 16, 2017

#45920 turned up some usages of inline assembly which have no outputs. LLVM will just remove such inline assembly as they can never be used. We should make this an error.
@parched
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parched commented Nov 16, 2017

Alternatively, do what GCC does and add volatile automatically if there are no outputs.

@kennytm kennytm added A-inline-assembly Area: Inline assembly (`asm!(…)`) C-feature-request Category: A feature request, i.e: not implemented / a PR. labels Nov 16, 2017
@sunfishcode
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It's worth considering an error though; inline asm is uncommon and extraordinarily unsafe, conditions which generally favor explicitness over implicitness.

@alexcrichton alexcrichton mentioned this issue Nov 17, 2017
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kennytm added a commit to kennytm/rust that referenced this issue Feb 5, 2018
@kennytm
Rollup merge of rust-lang#46030 - Zoxc:asm-volatile, r=nikomatsakis
eb5a461 
Make inline assembly volatile if it has no outputs. Fixes rust-lang#46026
@bors bors closed this as completed in a29d854 Feb 6, 2018
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A-inline-assembly Area: Inline assembly (`asm!(…)`) C-feature-request Category: A feature request, i.e: not implemented / a PR.
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