ISLE: Enable the overlap checker (#5011)

This PR turns the overlap checker on by default, requiring the use of priorities to resolve overlap between rules.

cranelift/codegen/src/isa/aarch64/lower.isle

@@ -1,7 +1,5 @@
 ;; aarch64 instruction selection and CLIF-to-MachInst lowering.
 
-(pragma overlap_errors)
-
 ;; The main lowering constructor term: takes a clif `Inst` and returns the
 ;; register(s) within which the lowered instruction's result values live.
 (decl lower (Inst) InstOutput)

cranelift/codegen/src/isa/riscv64/lower.isle

@@ -1,7 +1,5 @@
 ;; riscv64 instruction selection and CLIF-to-MachInst lowering.
 
-(pragma overlap_errors)
-
 ;; The main lowering constructor term: takes a clif `Inst` and returns the
 ;; register(s) within which the lowered instruction's result values live.
 (decl lower (Inst) InstOutput)

cranelift/codegen/src/isa/s390x/lower.isle

@@ -1,7 +1,5 @@
 ;; s390x instruction selection and CLIF-to-MachInst lowering.
 
-(pragma overlap_errors)
-
 ;; The main lowering constructor term: takes a clif `Inst` and returns the
 ;; register(s) within which the lowered instruction's result values live.
 (decl lower (Inst) InstOutput)

cranelift/codegen/src/isa/x64/lower.isle

@@ -1,8 +1,5 @@
 ;; x86-64 instruction selection and CLIF-to-MachInst lowering.
 
-;; Enable overlap checking for the x64 backend
-(pragma overlap_errors)
-
 ;; The main lowering constructor term: takes a clif `Inst` and returns the
 ;; register(s) within which the lowered instruction's result values live.
 (decl lower (Inst) InstOutput)

cranelift/isle/isle/isle_examples/link/iflets.isle

@@ -11,7 +11,7 @@
 (decl pure predicate () u32)
 (rule (predicate) 1)
 
-(rule (C a b c (B d e))
+(rule 2 (C a b c (B d e))
       (if-let (B f g) d)
       (if-let h (A a b))
       (A h a))
@@ -20,10 +20,10 @@
       (if (predicate))
       42)
 
-(rule (C a b a b)
+(rule 1 (C a b a b)
       (if-let x (D a b))
       x)
 
 (decl pure D (u32 u32) u32)
 (rule (D x 0) x)
-(rule (D 0 x) x)
+(rule 1 (D 0 x) x)

cranelift/isle/isle/isle_examples/link/multi_extractor.isle

@@ -7,7 +7,7 @@
 
 (decl Rule (u32) u32)
 
-(rule (Rule (E1 a idx))
+(rule 1 (Rule (E1 a idx))
       (if-let (A.B) a)
       idx)
 (rule (Rule _)

cranelift/isle/isle/isle_examples/pass/test3.isle

@@ -56,7 +56,7 @@
 (rule
   (Lower (Iadd ra rb))
   (MachInst.Add (UseInput ra) (UseInput rb)))
-(rule
+(rule 1
   (Lower (Iadd (Producer (Iadd ra rb)) rc))
   (MachInst.Add3 (UseInput ra) (UseInput rb) (UseInput rc)))
 (rule

cranelift/isle/isle/isle_examples/pass/tutorial.isle

@@ -51,12 +51,12 @@
 (extern constructor put_in_reg put_in_reg)
 
 ;; Simple rule for lowering adds.
-(rule (lower (HighLevelInst.Add a b))
+(rule -1 (lower (HighLevelInst.Add a b))
       (LowLevelInst.Add
         (AddrMode.RegReg (put_in_reg a) (put_in_reg b))))
 
 ;; Simple rule for lowering loads.
-(rule (lower (HighLevelInst.Load addr))
+(rule -1 (lower (HighLevelInst.Load addr))
       (LowLevelInst.Load 0 (put_in_reg addr)))
 
 ;; Declare an external extractor for extracting the instruction that defined a
@@ -72,7 +72,7 @@
                          0)))
 
 ;; Rule to sink a load of a base address with a static offset into a single add.
-(rule (lower (HighLevelInst.Add
+(rule 1 (lower (HighLevelInst.Add
                a
                (inst_result (HighLevelInst.Load
                               (inst_result (HighLevelInst.Add

cranelift/isle/isle/isle_examples/run/extractor_ordering_bug.isle

@@ -1,19 +0,0 @@
-
-(type u32 (primitive u32))
-
-(decl identity (u32) u32)
-(extern extractor infallible identity identity)
-
-(decl is_zero (u32) u32)
-(extern extractor is_zero is_zero)
-
-(decl test (u32) u32)
-
-;; This exposes a bug where infallible extractors were running before fallible
-;; ones, as the derived ordering for the `Extract` type was ordering them ahead
-;; of the fallible ones. The result is that the fallible `is_zero` extractor
-;; never runs, as the `identity` extractor will always succeed before it's
-;; called.
-(rule (test (identity x)) x)
-
-(rule (test (is_zero x)) 2)

cranelift/isle/isle/isle_examples/run/extractor_ordering_bug_main.rs

@@ -1,23 +0,0 @@
-mod extractor_ordering_bug;
-
-struct Context;
-impl extractor_ordering_bug::Context for Context {
-    fn is_zero(&mut self, val: u32) -> Option<u32> {
-        if val == 0 {
-            Some(val)
-        } else {
-            None
-        }
-    }
-
-    fn identity(&mut self, val: u32) -> u32 {
-        val
-    }
-}
-
-fn main() {
-    let mut ctx = Context;
-
-    assert_eq!(extractor_ordering_bug::constructor_test(&mut ctx, 0), Some(2));
-    assert_eq!(extractor_ordering_bug::constructor_test(&mut ctx, 1), Some(1));
-}

cranelift/isle/isle/src/ast.rs

@@ -33,8 +33,7 @@ pub struct Ident(pub String, pub Pos);
 /// Pragmas parsed with the `(pragma <ident>)` syntax.
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub enum Pragma {
-    /// Enable overlap errors in the source.
-    OverlapErrors,
+    // currently, no pragmas are defined, but the infrastructure is useful to keep around
 }
 
 /// A declaration of a type.

cranelift/isle/isle/src/overlap.rs

@@ -11,7 +11,6 @@ use crate::sema::{self, Rule, RuleId, Sym, TermEnv, TermId, TermKind, TypeEnv, V
 /// Check for overlap.
 pub fn check(tyenv: &TypeEnv, termenv: &TermEnv) -> Result<()> {
     let mut errors = check_overlaps(termenv).report(tyenv, termenv);
-    if termenv.overlap_errors {
     errors.sort_by_key(|err| match err {
         Error::OverlapError { rules, .. } => rules.first().unwrap().1.from,
         _ => Pos::default(),
@@ -21,11 +20,6 @@ pub fn check(tyenv: &TypeEnv, termenv: &TermEnv) -> Result<()> {
         1 => Err(errors.pop().unwrap()),
         _ => Err(Error::Errors(errors)),
     }
-    } else {
-        use crate::log;
-        log!("found {} overlap errors", errors.len());
-        Ok(())
-    }
 }
 
 /// A graph of rules that overlap in the ISLE source. The edges are undirected.

cranelift/isle/isle/src/parser.rs

@@ -200,9 +200,9 @@ impl<'a> Parser<'a> {
 
     fn parse_pragma(&mut self) -> Result<Pragma> {
         let ident = self.parse_ident()?;
-        match ident.0.as_ref() {
-            "overlap_errors" => Ok(Pragma::OverlapErrors),
-            _ => Err(self.error(ident.1, format!("Unknown pragma '{}'", ident.0))),
+        // currently, no pragmas are defined, but the infrastructure is useful to keep around
+        match ident.0.as_str() {
+            pragma => Err(self.error(ident.1, format!("Unknown pragma '{}'", pragma))),
         }
     }
 

cranelift/isle/isle/src/sema.rs

@@ -200,9 +200,6 @@ pub struct TermEnv {
     /// defined implicit type-converter terms we can try to use to fit
     /// types together.
     pub converters: StableMap<(TypeId, TypeId), TermId>,
-
-    /// A flag indicating whether or not overlap between rules should be considered an error.
-    pub overlap_errors: bool,
 }
 
 /// A term.
@@ -789,7 +786,6 @@ impl TermEnv {
             term_map: StableMap::new(),
             rules: vec![],
             converters: StableMap::new(),
-            overlap_errors: false,
         };
 
         env.collect_pragmas(defs);
@@ -811,13 +807,9 @@ impl TermEnv {
         Ok(env)
     }
 
-    fn collect_pragmas(&mut self, defs: &ast::Defs) {
-        for def in &defs.defs {
-            match def {
-                ast::Def::Pragma(ast::Pragma::OverlapErrors) => self.overlap_errors = true,
-                _ => (),
-            }
-        }
+    fn collect_pragmas(&mut self, _: &ast::Defs) {
+        // currently, no pragmas are defined, but the infrastructure is useful to keep around
+        return;
     }
 
     fn collect_term_sigs(&mut self, tyenv: &mut TypeEnv, defs: &ast::Defs) {