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Fix setting inline hint based on InstanceDef::requires_inline #79106

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merged 1 commit into from
Nov 19, 2020
Merged

Fix setting inline hint based on InstanceDef::requires_inline #79106

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16 changes: 4 additions & 12 deletions compiler/rustc_codegen_llvm/src/attributes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,7 @@ use crate::value::Value;

/// Mark LLVM function to use provided inline heuristic.
#[inline]
fn inline(cx: &CodegenCx<'ll, '_>, val: &'ll Value, inline: InlineAttr) {
fn inline(cx: &CodegenCx<'ll, '_>, val: &'ll Value, inline: InlineAttr, requires_inline: bool) {
use self::InlineAttr::*;
match inline {
Hint => Attribute::InlineHint.apply_llfn(Function, val),
Expand All @@ -35,11 +35,8 @@ fn inline(cx: &CodegenCx<'ll, '_>, val: &'ll Value, inline: InlineAttr) {
Attribute::NoInline.apply_llfn(Function, val);
}
}
None => {
Attribute::InlineHint.unapply_llfn(Function, val);
Attribute::AlwaysInline.unapply_llfn(Function, val);
Attribute::NoInline.unapply_llfn(Function, val);
}
None if requires_inline => Attribute::InlineHint.apply_llfn(Function, val),
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What's the intended behaviour here when requires_inline == true and inline != None?

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If its not something that can happen, maybe bug!() it?

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Requires inline instances are mostly auto-generated. Closures are the exception, so it is possible but unlikely. As far as what should take priority, no idea what the intent was, if it was considered at all (although the order of calls would suggest respecting user provided attributes).

None => {}
};
}

Expand Down Expand Up @@ -229,12 +226,7 @@ pub fn from_fn_attrs(cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value, instance: ty::
}
}

// FIXME(eddyb) consolidate these two `inline` calls (and avoid overwrites).
if instance.def.requires_inline(cx.tcx) {
inline(cx, llfn, attributes::InlineAttr::Hint);
}

inline(cx, llfn, codegen_fn_attrs.inline.clone());
inline(cx, llfn, codegen_fn_attrs.inline.clone(), instance.def.requires_inline(cx.tcx));

// The `uwtable` attribute according to LLVM is:
//
Expand Down
31 changes: 31 additions & 0 deletions src/test/codegen/inline-hint.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,31 @@
// Checks that closures, constructors, and shims except
// for a drop glue receive inline hint by default.
//
// compile-flags: -Cno-prepopulate-passes -Zsymbol-mangling-version=v0
#![crate_type = "lib"]

pub fn f() {
let a = A;
let b = (0i32, 1i32, 2i32, 3i32);
let c = || {};

a(String::new(), String::new());
b.clone();
c();
}

struct A(String, String);

// CHECK: ; core::ptr::drop_in_place::<inline_hint::A>
// CHECK-NEXT: ; Function Attrs:
// CHECK-NOT: inlinehint
// CHECK-SAME: {{$}}

// CHECK: ; <(i32, i32, i32, i32) as core::clone::Clone>::clone
// CHECK-NEXT: ; Function Attrs: inlinehint

// CHECK: ; inline_hint::f::{closure#0}
// CHECK-NEXT: ; Function Attrs: inlinehint

// CHECK: ; inline_hint::A
// CHECK-NEXT: ; Function Attrs: inlinehint