Make globals always have 2+ chars as suffix

As discussed on chat, there currently is the bug where certain suffixes
are interpreted by the (m68k) assembler.

Example: `move.l #global.w,-44(%fp)`
`.w` is interpreted by the assembler as a size hint for #global.

Author: fluxchief

src/context.rs

@@ -6,7 +6,7 @@ use gccjit::{
 use rustc_codegen_ssa::base::wants_msvc_seh;
 use rustc_codegen_ssa::errors as ssa_errors;
 use rustc_codegen_ssa::traits::{BackendTypes, BaseTypeCodegenMethods, MiscCodegenMethods};
-use rustc_data_structures::base_n::{ALPHANUMERIC_ONLY, ToBaseN};
+use rustc_data_structures::base_n::{ToBaseN, ALPHANUMERIC_ONLY};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_middle::mir::mono::CodegenUnit;
 use rustc_middle::span_bug;
@@ -17,7 +17,7 @@ use rustc_middle::ty::layout::{
 use rustc_middle::ty::{self, Instance, PolyExistentialTraitRef, Ty, TyCtxt};
 use rustc_session::Session;
 use rustc_span::source_map::respan;
-use rustc_span::{DUMMY_SP, Span};
+use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{HasDataLayout, PointeeInfo, Size, TargetDataLayout, VariantIdx};
 use rustc_target::spec::{
     HasTargetSpec, HasWasmCAbiOpt, HasX86AbiOpt, Target, TlsModel, WasmCAbi, X86Abi,
@@ -606,7 +606,10 @@ impl<'b, 'tcx> CodegenCx<'b, 'tcx> {
         let mut name = String::with_capacity(prefix.len() + 6);
         name.push_str(prefix);
         name.push('.');
-        name.push_str(&(idx as u64).to_base(ALPHANUMERIC_ONLY));
+        // Offset the index by the base so that always at least two characters
+        // are generated. This avoids cases where the suffix is interpreted as
+        // size by the assembler (for m68k: .b, .w, .l).
+        name.push_str(&(idx as u64 + ALPHANUMERIC_ONLY as u64).to_base(ALPHANUMERIC_ONLY));
         name
     }
 }