cranelift-filetests: tell when a run test is skipped (fixes #1558);

cranelift/filetests/src/runone.rs

@@ -75,6 +75,7 @@ pub fn run(path: &Path, passes: Option<&[String]>, target: Option<&str>) -> Test
         Some(t) => t,
     };
 
+    let file_path = path.to_string_lossy();
     for (func, details) in testfile.functions {
         let mut context = Context {
             preamble_comments: &testfile.preamble_comments,
@@ -82,6 +83,7 @@ pub fn run(path: &Path, passes: Option<&[String]>, target: Option<&str>) -> Test
             verified: false,
             flags,
             isa: None,
+            file_path: file_path.as_ref(),
         };
 
         for tuple in &tuples {

cranelift/filetests/src/subtest.rs

@@ -26,6 +26,9 @@ pub struct Context<'a> {
     /// Target ISA to test against. Only guaranteed to be present for sub-tests whose `needs_isa`
     /// method returned `true`. For other sub-tests, this is set if the test file has a unique ISA.
     pub isa: Option<&'a dyn TargetIsa>,
+
+    /// Full path to the file containing the test.
+    pub file_path: &'a str,
 }
 
 impl<'a> Context<'a> {

cranelift/filetests/src/test_run.rs

@@ -36,6 +36,18 @@ impl SubTest for TestRun {
     }
 
     fn run(&self, func: Cow<ir::Function>, context: &Context) -> SubtestResult<()> {
+        // If this test requests to run on a completely different
+        // architecture than the host platform then we skip it entirely,
+        // since we won't be able to natively execute machine code.
+        let requested_arch = context.isa.unwrap().triple().architecture;
+        if requested_arch != Architecture::host() {
+            println!(
+                "skipped {}: host can't run {:?} programs",
+                context.file_path, requested_arch
+            );
+            return Ok(());
+        }
+
         let mut compiler = SingleFunctionCompiler::with_host_isa(context.flags.clone());
         for comment in context.details.comments.iter() {
             if let Some(command) =
@@ -43,14 +55,6 @@ impl SubTest for TestRun {
             {
                 trace!("Parsed run command: {}", command);
 
-                // If this test requests to run on a completely different
-                // architecture than the host platform then we skip it entirely,
-                // since we won't be able to natively execute machine code.
-                let requested_arch = context.isa.unwrap().triple().architecture;
-                if requested_arch != Architecture::host() {
-                    return Ok(());
-                }
-
                 // Note that here we're also explicitly ignoring `context.isa`,
                 // regardless of what's requested. We want to use the native
                 // host ISA no matter what here, so the ISA listed in the file