always use gep inbounds i8 (ptradd) for field offsets

2 files changed, 5 insertions, 30 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/place.rs b/compiler/rustc_codegen_ssa/src/mir/place.rs
index 73c08e2ca61..0ce890dca32 100644
--- a/compiler/rustc_codegen_ssa/src/mir/place.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/place.rs
@@ -9,7 +9,7 @@ use rustc_middle::mir;
 use rustc_middle::mir::tcx::PlaceTy;
 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, TyAndLayout};
 use rustc_middle::ty::{self, Ty};
-use rustc_target::abi::{Abi, Align, FieldsShape, Int, Pointer, TagEncoding};
+use rustc_target::abi::{Align, FieldsShape, Int, Pointer, TagEncoding};
 use rustc_target::abi::{VariantIdx, Variants};
 
 #[derive(Copy, Clone, Debug)]
@@ -102,34 +102,10 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> {
         // `simple` is called when we don't need to adjust the offset to
         // the dynamic alignment of the field.
         let mut simple = || {
-            let llval = match self.layout.abi {
-                _ if offset.bytes() == 0 => {
-                    // Unions and newtypes only use an offset of 0.
-                    // Also handles the first field of Scalar, ScalarPair, and Vector layouts.
-                    self.llval
-                }
-                Abi::ScalarPair(..) => {
-                    // FIXME(nikic): Generate this for all ABIs.
-                    bx.inbounds_gep(bx.type_i8(), self.llval, &[bx.const_usize(offset.bytes())])
-                }
-                Abi::Scalar(_) | Abi::Vector { .. } if field.is_zst() => {
-                    // ZST fields (even some that require alignment) are not included in Scalar,
-                    // ScalarPair, and Vector layouts, so manually offset the pointer.
-                    bx.gep(bx.cx().type_i8(), self.llval, &[bx.const_usize(offset.bytes())])
-                }
-                Abi::Scalar(_) => {
-                    // All fields of Scalar layouts must have been handled by this point.
-                    // Vector layouts have additional fields for each element of the vector, so don't panic in that case.
-                    bug!(
-                        "offset of non-ZST field `{:?}` does not match layout `{:#?}`",
-                        field,
-                        self.layout
-                    );
-                }
-                _ => {
-                    let ty = bx.backend_type(self.layout);
-                    bx.struct_gep(ty, self.llval, bx.cx().backend_field_index(self.layout, ix))
-                }
+            let llval = if offset.bytes() == 0 {
+                self.llval
+            } else {
+                bx.inbounds_gep(bx.type_i8(), self.llval, &[bx.const_usize(offset.bytes())])
             };
             PlaceRef {
                 llval,
diff --git a/compiler/rustc_codegen_ssa/src/traits/type_.rs b/compiler/rustc_codegen_ssa/src/traits/type_.rs
index b1fde8e4d86..fb38a920332 100644
--- a/compiler/rustc_codegen_ssa/src/traits/type_.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/type_.rs
@@ -111,7 +111,6 @@ pub trait LayoutTypeMethods<'tcx>: Backend<'tcx> {
     fn immediate_backend_type(&self, layout: TyAndLayout<'tcx>) -> Self::Type;
     fn is_backend_immediate(&self, layout: TyAndLayout<'tcx>) -> bool;
     fn is_backend_scalar_pair(&self, layout: TyAndLayout<'tcx>) -> bool;
-    fn backend_field_index(&self, layout: TyAndLayout<'tcx>, index: usize) -> u64;
     fn scalar_pair_element_backend_type(
         &self,
         layout: TyAndLayout<'tcx>,