Prepare gep for opaque pointers

Implement gep using LLVMBuildGEP2 which takes an explicit type argument
instead of deriving it from a pointer type.

3 files changed, 6 insertions, 4 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs b/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
index 56ff1b3934c..b7ca19aba89 100644
--- a/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
@@ -121,9 +121,11 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 bx.inbounds_gep(ptr, &[offset])
             }
             sym::arith_offset => {
+                let ty = substs.type_at(0);
+                let layout = bx.layout_of(ty);
                 let ptr = args[0].immediate();
                 let offset = args[1].immediate();
-                bx.gep(ptr, &[offset])
+                bx.gep(bx.backend_type(layout), ptr, &[offset])
             }
             sym::copy => {
                 copy_intrinsic(
diff --git a/compiler/rustc_codegen_ssa/src/mir/place.rs b/compiler/rustc_codegen_ssa/src/mir/place.rs
index b8940245400..40961839e3f 100644
--- a/compiler/rustc_codegen_ssa/src/mir/place.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/place.rs
@@ -109,7 +109,7 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> {
                 Abi::Scalar(_) | Abi::ScalarPair(..) | Abi::Vector { .. } if field.is_zst() => {
                     // ZST fields are not included in Scalar, ScalarPair, and Vector layouts, so manually offset the pointer.
                     let byte_ptr = bx.pointercast(self.llval, bx.cx().type_i8p());
-                    bx.gep(byte_ptr, &[bx.const_usize(offset.bytes())])
+                    bx.gep(bx.cx().type_i8(), byte_ptr, &[bx.const_usize(offset.bytes())])
                 }
                 Abi::Scalar(_) | Abi::ScalarPair(..) => {
                     // All fields of Scalar and ScalarPair layouts must have been handled by this point.
@@ -189,7 +189,7 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> {
 
         // Cast and adjust pointer.
         let byte_ptr = bx.pointercast(self.llval, bx.cx().type_i8p());
-        let byte_ptr = bx.gep(byte_ptr, &[offset]);
+        let byte_ptr = bx.gep(bx.cx().type_i8(), byte_ptr, &[offset]);
 
         // Finally, cast back to the type expected.
         let ll_fty = bx.cx().backend_type(field);
diff --git a/compiler/rustc_codegen_ssa/src/traits/builder.rs b/compiler/rustc_codegen_ssa/src/traits/builder.rs
index 6c3f52b1b19..5e8ebcf9682 100644
--- a/compiler/rustc_codegen_ssa/src/traits/builder.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/builder.rs
@@ -176,7 +176,7 @@ pub trait BuilderMethods<'a, 'tcx>:
         size: Size,
     );
 
-    fn gep(&mut self, ptr: Self::Value, indices: &[Self::Value]) -> Self::Value;
+    fn gep(&mut self, ty: Self::Type, ptr: Self::Value, indices: &[Self::Value]) -> Self::Value;
     fn inbounds_gep(&mut self, ptr: Self::Value, indices: &[Self::Value]) -> Self::Value;
     fn struct_gep(&mut self, ty: Self::Type, ptr: Self::Value, idx: u64) -> Self::Value;