Conditional schedules

• Add if statements to the scheduling language.
• Add a feature(...) function that can be used to test for whether a feature is enabled
  • For this to work, the scheduler needs to be run from a Cargo build script since it relies on testing environment variables (as described here).
• Modified matmul to use a single schedule testing for the "cuda" feature

juno_scheduler/src/compile.rs

@@ -22,6 +22,7 @@ pub enum ScheduleCompilerError {
         actual: usize,
         loc: Location,
     },
+    SemanticError(String, Location),
 }
 
 impl fmt::Display for ScheduleCompilerError {
@@ -46,6 +47,11 @@ impl fmt::Display for ScheduleCompilerError {
                 "({}, {}) -- ({}, {}): Expected {} arguments, found {}",
                 loc.0 .0, loc.0 .1, loc.1 .0, loc.1 .1, expected, actual
             ),
+            ScheduleCompilerError::SemanticError(msg, loc) => write!(
+                f,
+                "({}, {}) -- ({}, {}): {}",
+                loc.0 .0, loc.0 .1, loc.1 .0, loc.1 .1, msg,
+            ),
         }
     }
 }
@@ -76,6 +82,8 @@ enum Appliable {
     // DeleteUncalled requires special handling because it changes FunctionIDs, so it is not
     // treated like a pass
     DeleteUncalled,
+    // Test whether a feature is enabled
+    Feature,
     Schedule(Schedule),
     Device(Device),
 }
@@ -85,6 +93,8 @@ impl Appliable {
     fn is_valid_num_args(&self, num: usize) -> bool {
         match self {
             Appliable::Pass(pass) => pass.is_valid_num_args(num),
+            // Testing whether a feature is enabled takes the feature instead of a selection, so it
+            // has 0 arguments
             // Delete uncalled, Schedules, and devices do not take arguments
             _ => num == 0,
         }
@@ -158,6 +168,8 @@ impl FromStr for Appliable {
             "serialize" => Ok(Appliable::Pass(ir::Pass::Serialize)),
             "write-predication" => Ok(Appliable::Pass(ir::Pass::WritePredication)),
 
+            "feature" => Ok(Appliable::Feature),
+
             "print" => Ok(Appliable::Pass(ir::Pass::Print)),
 
             "cpu" | "llvm" => Ok(Appliable::Device(Device::LLVM)),
@@ -409,6 +421,17 @@ fn compile_expr(
                         on: selection,
                     }))
                 }
+                Appliable::Feature => match selection {
+                    ir::Selector::Selection(mut args) if args.len() == 1 => {
+                        Ok(ExprResult::Expr(ir::ScheduleExp::Feature {
+                            feature: Box::new(args.pop().unwrap()),
+                        }))
+                    }
+                    _ => Err(ScheduleCompilerError::SemanticError(
+                        "feature requires exactly one argument as its selection".to_string(),
+                        lexer.line_col(span),
+                    )),
+                },
                 Appliable::Schedule(sched) => Ok(ExprResult::Stmt(ir::ScheduleStmt::AddSchedule {
                     sched,
                     on: selection,