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Auto merge of #76071 - khyperia:configurable_to_immediate, r=eddyb

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Make to_immediate/from_immediate configurable by backends

`librustc_codegen_ssa` has the concept of an immediate vs. memory type, and `librustc_codegen_llvm` uses this distinction to implement `bool`s being `i8` in memory, and `i1` in immediate contexts. However, some of that implementation leaked into `codegen_ssa` when converting to/from immediate values. So, move those methods into builder traits, so that behavior can be configured by backends.

This is useful if a backend is able to keep bools as bools, or, needs to do more trickery than just bools to bytes.

(Note that there's already a large amount of things abstracted with "immediate types" - this is just bringing this particular thing in line to be abstracted as well)

---

Pinging @eddyb since that's who I was talking about this change with when they suggested I submit a PR.
This commit is contained in:
bors 2020-09-01 07:44:34 +00:00
commit 6f1bbf5ee0
7 changed files with 56 additions and 68 deletions
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19
compiler/rustc_codegen_llvm/src/builder.rs
View file

@ -6,7 +6,6 @@ use crate::type_::Type;
use crate::type_of::LayoutLlvmExt;
use crate::value::Value;
use libc::{c_char, c_uint};
use rustc_codegen_ssa::base::to_immediate;
use rustc_codegen_ssa::common::{IntPredicate, RealPredicate, TypeKind};
use rustc_codegen_ssa::mir::operand::{OperandRef, OperandValue};
use rustc_codegen_ssa::mir::place::PlaceRef;
@ -367,6 +366,20 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
(self.extract_value(res, 0), self.extract_value(res, 1))
}
fn from_immediate(&mut self, val: Self::Value) -> Self::Value {
if self.cx().val_ty(val) == self.cx().type_i1() {
self.zext(val, self.cx().type_i8())
} else {
val
}
}
fn to_immediate_scalar(&mut self, val: Self::Value, scalar: &abi::Scalar) -> Self::Value {
if scalar.is_bool() {
return self.trunc(val, self.cx().type_i1());
}
val
}
fn alloca(&mut self, ty: &'ll Type, align: Align) -> &'ll Value {
let mut bx = Builder::with_cx(self.cx);
bx.position_at_start(unsafe { llvm::LLVMGetFirstBasicBlock(self.llfn()) });
@ -471,7 +484,7 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
}
load
});
OperandValue::Immediate(to_immediate(self, llval, place.layout))
OperandValue::Immediate(self.to_immediate(llval, place.layout))
} else if let abi::Abi::ScalarPair(ref a, ref b) = place.layout.abi {
let b_offset = a.value.size(self).align_to(b.value.align(self).abi);
@ -479,7 +492,7 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
let llptr = self.struct_gep(place.llval, i as u64);
let load = self.load(llptr, align);
scalar_load_metadata(self, load, scalar);
if scalar.is_bool() { self.trunc(load, self.type_i1()) } else { load }
self.to_immediate_scalar(load, scalar)
};
OperandValue::Pair(

4
compiler/rustc_codegen_llvm/src/intrinsic.rs
View file

@ -8,7 +8,7 @@ use crate::va_arg::emit_va_arg;
use crate::value::Value;
use rustc_ast as ast;
use rustc_codegen_ssa::base::{compare_simd_types, to_immediate, wants_msvc_seh};
use rustc_codegen_ssa::base::{compare_simd_types, wants_msvc_seh};
use rustc_codegen_ssa::common::span_invalid_monomorphization_error;
use rustc_codegen_ssa::common::{IntPredicate, TypeKind};
use rustc_codegen_ssa::glue;
@ -301,7 +301,7 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
unsafe {
llvm::LLVMSetAlignment(load, align);
}
to_immediate(self, load, self.layout_of(tp_ty))
self.to_immediate(load, self.layout_of(tp_ty))
}
sym::volatile_store => {
let dst = args[0].deref(self.cx());