Expose parsing of run commands and trivially use in testing framework

This is necessary to avoid build errors from dead code (and I didn't want to litter all of the structs with `#[allow(dead_code)]` just to remove in a subsequent PR).

cranelift/filetests/src/test_run.rs

@@ -6,7 +6,9 @@ use crate::function_runner::FunctionRunner;
 use crate::subtest::{Context, SubTest, SubtestResult};
 use cranelift_codegen;
 use cranelift_codegen::ir;
+use cranelift_reader::parse_run_command;
 use cranelift_reader::TestCommand;
+use log::trace;
 use std::borrow::Cow;
 
 struct TestRun;
@@ -36,6 +38,12 @@ impl SubTest for TestRun {
     fn run(&self, func: Cow<ir::Function>, context: &Context) -> SubtestResult<()> {
         for comment in context.details.comments.iter() {
             if comment.text.contains("run") {
+                let trimmed_comment = comment.text.trim_start_matches(|c| c == ' ' || c == ';');
+                let command = parse_run_command(trimmed_comment, &func.signature)
+                    .map_err(|e| format!("{}", e))?;
+                trace!("Parsed run command: {}", command);
+                // TODO in following changes we will use the parsed command to alter FunctionRunner's behavior.
+
                 let runner =
                     FunctionRunner::with_host_isa(func.clone().into_owned(), context.flags.clone());
                 runner.run()?

cranelift/reader/src/lib.rs

@@ -28,7 +28,8 @@
 
 pub use crate::error::{Location, ParseError, ParseResult};
 pub use crate::isaspec::{parse_options, IsaSpec};
-pub use crate::parser::{parse_functions, parse_test, ParseOptions};
+pub use crate::parser::{parse_functions, parse_run_command, parse_test, ParseOptions};
+pub use crate::run_command::{Comparison, DataValue, Invocation, RunCommand};
 pub use crate::sourcemap::SourceMap;
 pub use crate::testcommand::{TestCommand, TestOption};
 pub use crate::testfile::{Comment, Details, Feature, TestFile};

cranelift/reader/src/parser.rs

@@ -114,6 +114,13 @@ pub fn parse_test<'a>(text: &'a str, options: ParseOptions<'a>) -> ParseResult<T
     })
 }
 
+/// Parse the entire `text` as a run command.
+pub fn parse_run_command<'a>(text: &str, signature: &Signature) -> ParseResult<RunCommand> {
+    let _tt = timing::parse_text();
+    let mut parser = Parser::new(text);
+    parser.parse_run_command(signature)
+}
+
 pub struct Parser<'a> {
     lex: Lexer<'a>,
 

cranelift/src/run.rs

@@ -92,7 +92,9 @@ fn run_file_contents(file_contents: String) -> Result<(), String> {
     let test_file = parse_test(&file_contents, options).map_err(|e| e.to_string())?;
     for (func, Details { comments, .. }) in test_file.functions {
         if comments.iter().any(|c| c.text.contains("run")) {
+            // TODO in following changes we will parse this comment to alter the FunctionRunner's behavior.
             let isa = create_target_isa(&test_file.isa_spec)?;
+            // TODO the following no longer makes sense; use FunctionRunner::with_host_isa(...) instead
             FunctionRunner::new(func, isa).run()?
         }
     }