| @@ -39,7 +39,7 @@ pub enum Stability { |
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allow_toggle: Toggleability, |
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}, |
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/// This feature can not be set via `-Ctarget-feature` or `#[target_feature]`, it can only be |
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- /// set in the basic target definition. It is never set in `cfg(target_feature)`. Used in |
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+ /// set in the target spec. It is never set in `cfg(target_feature)`. Used in |
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/// particular for features that change the floating-point ABI. |
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Forbidden { reason: &'static str }, |
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} |
| @@ -600,7 +600,8 @@ const RISCV_FEATURES: &[(&str, StabilityUncomputed, ImpliedFeatures)] = &[ |
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Err("feature is required by ABI") |
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} |
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"ilp32e" if enable => { |
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-// The `d` feature apparently is incompatible with this ABI. |
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+// ilp32e is incompatible with features that need aligned load/stores > 32 bits, |
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+// like `d`. |
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Err("feature is incompatible with ABI") |
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} |
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_ => Ok(()), |
| @@ -618,7 +619,10 @@ const RISCV_FEATURES: &[(&str, StabilityUncomputed, ImpliedFeatures)] = &[ |
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allow_toggle: |target, enable |
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match &*target.llvm_abiname { |
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_ if !enable => { |
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-// This is a negative feature, *disabling* it is always okay. |
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+// Disabling this feature means we can use more registers (x16-x31). |
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+// The "e" ABIs treat them as caller-save, so it is safe to use them only |
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+// in some parts of a program while the rest doesn't know they even exist. |
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+// On other ABIs, the feature is already disabled anyway. |
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Ok(()) |
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} |
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"ilp32e" | "lp64e" => { |