Merge pull request #1975 from MaxGraey/more-peephole-opts

peepmatic: add reminder by a power of two rule

cranelift/codegen/src/preopt.peepmatic

@@ -191,3 +191,9 @@
 (=> (when (udiv_imm $C $x)
           (is-power-of-two $C))
     (ushr_imm $(log2 $C) $x))
+
+;; Remainder by a power of two -> bitwise and with decreased by one constant.
+(=> (when (urem_imm $C $x)
+          (is-power-of-two $C)
+          (fits-in-native-word $C))
+    (band_imm $(isub $C 1) $x))

cranelift/peepmatic/crates/runtime/src/operator.rs

@@ -237,6 +237,10 @@ pub enum UnquoteOperator {
     #[peepmatic(params(iNN, iNN), result(iNN))]
     Imul,
 
+    /// Compile-time `isub` of two constant values.
+    #[peepmatic(params(iNN, iNN), result(iNN))]
+    Isub,
+
     /// Take the base-2 log of a power of two integer.
     #[peepmatic(params(iNN), result(iNN))]
     Log2,

cranelift/peepmatic/crates/runtime/src/optimizer.rs

@@ -77,7 +77,8 @@ where
             | UnquoteOperator::Bor
             | UnquoteOperator::Bxor
             | UnquoteOperator::Iadd
-            | UnquoteOperator::Imul => unreachable!("not a unary unquote operator: {:?}", operator),
+            | UnquoteOperator::Imul
+            | UnquoteOperator::Isub => unreachable!("not a unary unquote operator: {:?}", operator),
         }
     }
 
@@ -99,6 +100,7 @@ where
             UnquoteOperator::Bxor => fold_ints!(a, b, |x, y| x ^ y),
             UnquoteOperator::Iadd => fold_ints!(a, b, |x, y| x.wrapping_add(y)),
             UnquoteOperator::Imul => fold_ints!(a, b, |x, y| x.wrapping_mul(y)),
+            UnquoteOperator::Isub => fold_ints!(a, b, |x, y| x.wrapping_sub(y)),
             UnquoteOperator::Log2 | UnquoteOperator::Neg => {
                 unreachable!("not a binary unquote operator: {:?}", operator)
             }