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

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.

1 files changed, 12 insertions, 2 deletions

diff --git a/compiler/rustc_codegen_ssa/src/traits/builder.rs b/compiler/rustc_codegen_ssa/src/traits/builder.rs
index 5ffc83c5f99..5142922260a 100644
--- a/compiler/rustc_codegen_ssa/src/traits/builder.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/builder.rs
@@ -13,9 +13,9 @@ use crate::mir::operand::OperandRef;
 use crate::mir::place::PlaceRef;
 use crate::MemFlags;
 
-use rustc_middle::ty::layout::HasParamEnv;
+use rustc_middle::ty::layout::{HasParamEnv, TyAndLayout};
 use rustc_middle::ty::Ty;
-use rustc_target::abi::{Align, Size};
+use rustc_target::abi::{Abi, Align, Scalar, Size};
 use rustc_target::spec::HasTargetSpec;
 
 use std::iter::TrustedLen;
@@ -115,6 +115,16 @@ pub trait BuilderMethods<'a, 'tcx>:
         rhs: Self::Value,
     ) -> (Self::Value, Self::Value);
 
+    fn from_immediate(&mut self, val: Self::Value) -> Self::Value;
+    fn to_immediate(&mut self, val: Self::Value, layout: TyAndLayout<'_>) -> Self::Value {
+        if let Abi::Scalar(ref scalar) = layout.abi {
+            self.to_immediate_scalar(val, scalar)
+        } else {
+            val
+        }
+    }
+    fn to_immediate_scalar(&mut self, val: Self::Value, scalar: &Scalar) -> Self::Value;
+
     fn alloca(&mut self, ty: Self::Type, align: Align) -> Self::Value;
     fn dynamic_alloca(&mut self, ty: Self::Type, align: Align) -> Self::Value;
     fn array_alloca(&mut self, ty: Self::Type, len: Self::Value, align: Align) -> Self::Value;