Avoid ICE when global_asm const operand fails to evaluate

Author: BeetleFunk

src/global_asm.rs

@@ -8,6 +8,7 @@ use std::sync::Arc;
 
 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_hir::{InlineAsmOperand, ItemId};
+use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_session::config::{OutputFilenames, OutputType};
 use rustc_target::asm::InlineAsmArch;
 
@@ -32,18 +33,27 @@ pub(crate) fn codegen_global_asm_item(tcx: TyCtxt<'_>, global_asm: &mut String,
                 InlineAsmTemplatePiece::Placeholder { operand_idx, modifier: _, span: op_sp } => {
                     match asm.operands[operand_idx].0 {
                         InlineAsmOperand::Const { ref anon_const } => {
-                            let const_value =
-                                tcx.const_eval_poly(anon_const.def_id.to_def_id()).unwrap_or_else(
-                                    |_| span_bug!(op_sp, "asm const cannot be resolved"),
-                                );
-                            let ty = tcx.typeck_body(anon_const.body).node_type(anon_const.hir_id);
-                            let string = rustc_codegen_ssa::common::asm_const_to_str(
-                                tcx,
-                                op_sp,
-                                const_value,
-                                RevealAllLayoutCx(tcx).layout_of(ty),
-                            );
-                            global_asm.push_str(&string);
+                            match tcx.const_eval_poly(anon_const.def_id.to_def_id()) {
+                                Ok(const_value) => {
+                                    let ty = tcx
+                                        .typeck_body(anon_const.body)
+                                        .node_type(anon_const.hir_id);
+                                    let string = rustc_codegen_ssa::common::asm_const_to_str(
+                                        tcx,
+                                        op_sp,
+                                        const_value,
+                                        RevealAllLayoutCx(tcx).layout_of(ty),
+                                    );
+                                    global_asm.push_str(&string);
+                                }
+                                Err(ErrorHandled::Reported { .. }) => {
+                                    // An error has already been reported and compilation is
+                                    // guaranteed to fail if execution hits this path.
+                                }
+                                Err(ErrorHandled::TooGeneric(_)) => {
+                                    span_bug!(op_sp, "asm const cannot be resolved; too generic");
+                                }
+                            }
                         }
                         InlineAsmOperand::SymFn { anon_const } => {
                             if cfg!(not(feature = "inline_asm_sym")) {