Always require a Flags reference for verifying functions.

Add a settings::FlagsOrIsa struct which represents a flags reference and
optionally the ISA it belongs to. Use this for passing flags/isa
information to the verifier.

The verify_function() and verify_context() functions are now generic so
they accept either a &Flags or a &TargetISa argument.

Fix the return_at_end verifier tests which no longer require an ISA
specified. The signle "set return_at_end" flag setting now makes it to
the verifier even when no ISA is present to carry it.

cranelift/src/filetest/licm.rs

@@ -41,7 +41,7 @@ impl SubTest for TestLICM {
         comp_ctx.flowgraph();
         comp_ctx.compute_loop_analysis();
         comp_ctx.licm();
-        comp_ctx.verify(context.isa).map_err(|e| {
+        comp_ctx.verify(context.flags_or_isa()).map_err(|e| {
             pretty_error(&comp_ctx.func, context.isa, Into::into(e))
         })?;
 

cranelift/src/filetest/runone.rs

@@ -119,9 +119,11 @@ fn run_one_test<'a>(
 
     // Should we run the verifier before this test?
     if !context.verified && test.needs_verifier() {
-        verify_function(&func, isa).map_err(|e| {
-            pretty_verifier_error(&func, isa, e)
-        })?;
+        verify_function(&func, context.flags_or_isa()).map_err(
+            |e| {
+                pretty_verifier_error(&func, isa, e)
+            },
+        )?;
         context.verified = true;
     }
 

cranelift/src/filetest/simple_gvn.rs

@@ -40,7 +40,7 @@ impl SubTest for TestSimpleGVN {
 
         comp_ctx.flowgraph();
         comp_ctx.simple_gvn();
-        comp_ctx.verify(context.isa).map_err(|e| {
+        comp_ctx.verify(context.flags_or_isa()).map_err(|e| {
             pretty_error(&comp_ctx.func, context.isa, Into::into(e))
         })?;
 

cranelift/src/filetest/subtest.rs

@@ -4,7 +4,7 @@ use std::result;
 use std::borrow::Cow;
 use cretonne::ir::Function;
 use cretonne::isa::TargetIsa;
-use cretonne::settings::Flags;
+use cretonne::settings::{Flags, FlagsOrIsa};
 use cton_reader::{Details, Comment};
 use filecheck::{self, CheckerBuilder, Checker, Value as FCValue};
 
@@ -29,6 +29,16 @@ pub struct Context<'a> {
     pub isa: Option<&'a TargetIsa>,
 }
 
+impl<'a> Context<'a> {
+    /// Get a `FlagsOrIsa` object for passing to the verifier.
+    pub fn flags_or_isa(&self) -> FlagsOrIsa<'a> {
+        FlagsOrIsa {
+            flags: self.flags,
+            isa: self.isa,
+        }
+    }
+}
+
 /// Common interface for implementations of test commands.
 ///
 /// Each `.cton` test file may contain multiple test commands, each represented by a `SubTest`

cranelift/src/filetest/verifier.rs

@@ -51,7 +51,7 @@ impl SubTest for TestVerifier {
             }
         }
 
-        match verify_function(func, context.isa) {
+        match verify_function(func, context.flags_or_isa()) {
             Ok(_) => {
                 match expected {
                     None => Ok(()),