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Implement branch prediction intrinsics #20579

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nagisa opened this issue Jan 5, 2015 · 4 comments
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Implement branch prediction intrinsics #20579

nagisa opened this issue Jan 5, 2015 · 4 comments
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A-codegen Area: Code generation

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@nagisa
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nagisa commented Jan 5, 2015

Branch prediction intrinsic equivalent to GCC’s __builtin_expect should exist. Alternatively two intrinsics likely and unlikely could be implemented.
@nagisa
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nagisa commented Jan 5, 2015

Appears to correspond to llvm.expect intrinsic.

@jdm
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jdm commented Jan 5, 2015

See #17317.

@nagisa
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nagisa commented Jan 5, 2015

I’m be fine with only expect_u* exposed from core::intrinsics. That wouldn’t need any RFC I think. While likely! and unlikely! are nice-to-have, they are simple enough to define in terms of the intrinsics.

@kmcallister kmcallister added the A-codegen Area: Code generation label Jan 5, 2015
@seanmonstar seanmonstar mentioned this issue Feb 28, 2015
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@nagisa nagisa mentioned this issue Feb 28, 2015
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@alexcrichton
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cc @steveklabnik, could this move to the rust-lang/rfcs repo? (feature request)

@nagisa nagisa mentioned this issue Feb 28, 2015
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@nagisa nagisa closed this as completed Feb 28, 2015
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core: add instrinsics for llvm.expect.i8-i64 seanmonstar/rust
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@jdm @alexcrichton @kmcallister @nagisa