Use unstable_target_features when checking inline assembly

This is necessary to properly validate register classes even when the
relevant target feature name is still unstable.

Author: Amanieu

Diff for: src/asm.rs

@@ -107,7 +107,7 @@ enum ConstraintOrRegister {
 
 
 impl<'a, 'gcc, 'tcx> AsmBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
-    fn codegen_inline_asm(&mut self, template: &[InlineAsmTemplatePiece], rust_operands: &[InlineAsmOperandRef<'tcx, Self>], options: InlineAsmOptions, span: &[Span], _instance: Instance<'_>, _dest_catch_funclet: Option<(Self::BasicBlock, Self::BasicBlock, Option<&Self::Funclet>)>) {
+    fn codegen_inline_asm(&mut self, template: &[InlineAsmTemplatePiece], rust_operands: &[InlineAsmOperandRef<'tcx, Self>], options: InlineAsmOptions, span: &[Span], instance: Instance<'_>, _dest_catch_funclet: Option<(Self::BasicBlock, Self::BasicBlock, Option<&Self::Funclet>)>) {
         if options.contains(InlineAsmOptions::MAY_UNWIND) {
             self.sess()
                 .create_err(UnwindingInlineAsm { span: span[0] })
@@ -173,7 +173,7 @@ impl<'a, 'gcc, 'tcx> AsmBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
                             let is_target_supported = reg.reg_class().supported_types(asm_arch).iter()
                                 .any(|&(_, feature)| {
                                     if let Some(feature) = feature {
-                                        self.tcx.sess.target_features.contains(&feature)
+                                        self.tcx.asm_target_features(instance.def_id()).contains(&feature)
                                     } else {
                                         true // Register class is unconditionally supported
                                     }