Auto merge of #94527 - oli-obk:undef_scalars, r=nagisa,erikdesjardin

Let CTFE to handle partially uninitialized unions without marking the entire value as uninitialized.

follow up to #94411

To fix https://github.com/rust-lang/rust/issues/69488 and by extension fix https://github.com/rust-lang/rust/issues/94371, we should stop treating types like `MaybeUninit<usize>` as something that the `Scalar` type in the interpreter engine can represent. So we add a new field to `abi::Primitive` that records whether the primitive is nested in a union

cc `@RalfJung`

r? `@ghost`

4 files changed, 11 insertions, 11 deletions

diff --git a/compiler/rustc_codegen_gcc/src/builder.rs b/compiler/rustc_codegen_gcc/src/builder.rs
index 21c7d420b20..41f88f119e2 100644
--- a/compiler/rustc_codegen_gcc/src/builder.rs
+++ b/compiler/rustc_codegen_gcc/src/builder.rs
@@ -694,11 +694,11 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         }
 
         fn scalar_load_metadata<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>, load: RValue<'gcc>, scalar: &abi::Scalar) {
-            let vr = scalar.valid_range.clone();
-            match scalar.value {
+            let vr = scalar.valid_range(bx);
+            match scalar.primitive() {
                 abi::Int(..) => {
                     if !scalar.is_always_valid(bx) {
-                        bx.range_metadata(load, scalar.valid_range);
+                        bx.range_metadata(load, vr);
                     }
                 }
                 abi::Pointer if vr.start < vr.end && !vr.contains(0) => {
@@ -720,7 +720,7 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
                 OperandValue::Immediate(self.to_immediate(load, 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);
+                let b_offset = a.size(self).align_to(b.align(self).abi);
                 let pair_type = place.layout.gcc_type(self, false);
 
                 let mut load = |i, scalar: &abi::Scalar, align| {
diff --git a/compiler/rustc_codegen_gcc/src/common.rs b/compiler/rustc_codegen_gcc/src/common.rs
index 19127c7612d..b056b6d4730 100644
--- a/compiler/rustc_codegen_gcc/src/common.rs
+++ b/compiler/rustc_codegen_gcc/src/common.rs
@@ -158,14 +158,14 @@ impl<'gcc, 'tcx> ConstMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
     }
 
     fn scalar_to_backend(&self, cv: Scalar, layout: abi::Scalar, ty: Type<'gcc>) -> RValue<'gcc> {
-        let bitsize = if layout.is_bool() { 1 } else { layout.value.size(self).bits() };
+        let bitsize = if layout.is_bool() { 1 } else { layout.size(self).bits() };
         match cv {
             Scalar::Int(ScalarInt::ZST) => {
-                assert_eq!(0, layout.value.size(self).bytes());
+                assert_eq!(0, layout.size(self).bytes());
                 self.const_undef(self.type_ix(0))
             }
             Scalar::Int(int) => {
-                let data = int.assert_bits(layout.value.size(self));
+                let data = int.assert_bits(layout.size(self));
 
                 // FIXME(antoyo): there's some issues with using the u128 code that follows, so hard-code
                 // the paths for floating-point values.
@@ -209,7 +209,7 @@ impl<'gcc, 'tcx> ConstMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
                 let base_addr = self.const_bitcast(base_addr, self.usize_type);
                 let offset = self.context.new_rvalue_from_long(self.usize_type, offset.bytes() as i64);
                 let ptr = self.const_bitcast(base_addr + offset, ptr_type);
-                if layout.value != Pointer {
+                if layout.primitive() != Pointer {
                     self.const_bitcast(ptr.dereference(None).to_rvalue(), ty)
                 }
                 else {
diff --git a/compiler/rustc_codegen_gcc/src/consts.rs b/compiler/rustc_codegen_gcc/src/consts.rs
index de52f3ea225..3dc456f1aa0 100644
--- a/compiler/rustc_codegen_gcc/src/consts.rs
+++ b/compiler/rustc_codegen_gcc/src/consts.rs
@@ -328,7 +328,7 @@ pub fn const_alloc_to_gcc<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, alloc: ConstAl
                 interpret::Pointer::new(alloc_id, Size::from_bytes(ptr_offset)),
                 &cx.tcx,
             ),
-            abi::Scalar { value: Primitive::Pointer, valid_range: WrappingRange { start: 0, end: !0 } },
+            abi::Scalar::Initialized { value: Primitive::Pointer, valid_range: WrappingRange::full(dl.pointer_size) },
             cx.type_i8p(),
         ));
         next_offset = offset + pointer_size;
diff --git a/compiler/rustc_codegen_gcc/src/type_of.rs b/compiler/rustc_codegen_gcc/src/type_of.rs
index ed8f0445ca3..2c042ba4e3a 100644
--- a/compiler/rustc_codegen_gcc/src/type_of.rs
+++ b/compiler/rustc_codegen_gcc/src/type_of.rs
@@ -224,7 +224,7 @@ impl<'tcx> LayoutGccExt<'tcx> for TyAndLayout<'tcx> {
     }
 
     fn scalar_gcc_type_at<'gcc>(&self, cx: &CodegenCx<'gcc, 'tcx>, scalar: &abi::Scalar, offset: Size) -> Type<'gcc> {
-        match scalar.value {
+        match scalar.primitive() {
             Int(i, true) => cx.type_from_integer(i),
             Int(i, false) => cx.type_from_unsigned_integer(i),
             F32 => cx.type_f32(),
@@ -282,7 +282,7 @@ impl<'tcx> LayoutGccExt<'tcx> for TyAndLayout<'tcx> {
                 Size::ZERO
             }
             else {
-                a.value.size(cx).align_to(b.value.align(cx).abi)
+                a.size(cx).align_to(b.align(cx).abi)
             };
         self.scalar_gcc_type_at(cx, scalar, offset)
     }