Cranelift: Remove some unneeded arithmetic.isle patterns (bytecodea…

…lliance#7599)

cranelift/codegen/src/opts/arithmetic.isle

@@ -1,15 +1,14 @@
 ;; rewrites for integer and floating-point arithmetic
 ;; eg: `iadd`, `isub`, `ineg`, `imul`, `fadd`, `fsub`, `fmul`
 
-;; x+0 == 0+x == x.
+;; For commutative instructions, we depend on cprop.isle pushing immediates to
+;; the right, and thus only simplify patterns like `x+0`, not `0+x`.
+
+;; x+0 == x.
 (rule (simplify (iadd ty
                       x
                       (iconst ty (u64_from_imm64 0))))
       (subsume x))
-(rule (simplify (iadd ty
-                      (iconst ty (u64_from_imm64 0))
-                      x))
-      (subsume x))
 ;; x-0 == x.
 (rule (simplify (isub ty
                       x
@@ -39,33 +38,22 @@
 ;; x-x == 0.
 (rule (simplify (isub (fits_in_64 (ty_int ty)) x x)) (subsume (iconst ty (imm64 0))))
 
-;; x*1 == 1*x == x.
+;; x*1 == x.
 (rule (simplify (imul ty
                       x
                       (iconst ty (u64_from_imm64 1))))
       (subsume x))
-(rule (simplify (imul ty
-                      (iconst ty (u64_from_imm64 1))
-                      x))
-      (subsume x))
 
-;; x*0 == 0*x == 0.
+;; x*0 == 0.
 (rule (simplify (imul ty
                       _
                       zero @ (iconst ty (u64_from_imm64 0))))
       (subsume zero))
-(rule (simplify (imul ty
-                      zero @ (iconst ty (u64_from_imm64 0))
-                      _))
-      (subsume zero))
 
-;; x*-1 == -1*x == ineg(x).
+;; x*-1 == ineg(x).
 (rule (simplify (imul ty x (iconst ty c)))
       (if-let -1 (i64_sextend_imm64 ty c))
       (ineg ty x))
-(rule (simplify (imul ty (iconst ty c) x))
-      (if-let -1 (i64_sextend_imm64 ty c))
-      (ineg ty x))
 
 ;; (!x) + 1 == 1 + (!x) == !(x) - (-1) == ineg(x)
 (rule (simplify (iadd ty (bnot ty x) (iconst ty (u64_from_imm64 1))))
@@ -99,11 +87,9 @@
 ;; TODO: strength reduction: div to shifts
 ;; TODO: div/rem by constants -> magic multiplications
 
-;; x*2 == 2*x == x+x.
+;; x*2 == x+x.
 (rule (simplify (imul ty x (iconst _ (simm32 2))))
       (iadd ty x x))
-(rule (simplify (imul ty (iconst _ (simm32 2)) x))
-      (iadd ty x x))
 
 ;; x*c == x<<log2(c) when c is a power of two.
 ;; Note that the type of `iconst` must be the same as the type of `imul`,

cranelift/filetests/filetests/egraph/arithmetic.clif

@@ -55,6 +55,39 @@ block0(v0: i32):
     ; check: return v2
 }
 
+function %zero_plus(i32) -> i32 {
+block0(v0: i32):
+    v1 = iconst.i32 0
+    v2 = iadd v1, v0
+    return v2
+    ; check: return v0
+}
+
+function %zero_times(i32) -> i32 {
+block0(v0: i32):
+    v1 = iconst.i32 0
+    v2 = imul v1, v0
+    return v2
+    ; check: return v1
+}
+
+function %one_times(i32) -> i32 {
+block0(v0: i32):
+    v1 = iconst.i32 1
+    v2 = imul v1, v0
+    return v2
+    ; check: return v0
+}
+
+function %two_times(i32) -> i32 {
+block0(v0: i32):
+    v1 = iconst.i32 2
+    v2 = imul v1, v0
+    return v2
+    ; check: v6 = iadd v0, v0
+    ; check: return v6
+}
+
 function %mul_minus_one(i32) -> i32 {
 block0(v0: i32):
     v1 = iconst.i32 0xffff_ffff ; -1
@@ -69,8 +102,8 @@ block0(v0: i32):
     v1 = iconst.i32 0xffff_ffff ; -1
     v2 = imul v1, v0
     return v2
-    ; check: v3 = ineg v0
-    ; check: return v3
+    ; check: v4 = ineg v0
+    ; check: return v4
 }
 
 function %ineg_not_plus_one(i32) -> i32 {

cranelift/filetests/filetests/egraph/associative-and-commutative.clif

@@ -39,9 +39,9 @@ block0(v0: i32, v1: i32):
     v6 = iadd v4, v5
     return v6
 ; check:  v7 = iadd v0, v1
-; nextln: iconst.i32 78
-; nextln: v16 = iadd v7, v14  ; v14 = 78
-; check:  return v16
+; nextln: v9 = iconst.i32 78
+; nextln: v15 = iadd v7, v9  ; v9 = 78
+; check:  return v15
 }
 
 function %imul_shallow_and_wide(i32, i32, i32, i32) -> i32 {

cranelift/filetests/filetests/egraph/cprop.clif

@@ -9,8 +9,8 @@ block0:
     return v2
 }
 
-; check: v9 = iconst.i8 41
-; nextln: return v9
+; check: v3 = iconst.i8 41
+; nextln: return v3
 
 function %f1() -> i16 {
 block0:

cranelift/filetests/filetests/egraph/remat.clif

@@ -22,10 +22,9 @@ block2:
 ; check:      v2 = iadd v0, v1
 ; check:      brif v2, block1, block2
 ; check:   block1:
-; check:      v11 = iconst.i32 126
-; check:      v13 = iadd.i32 v0, v11
-; check:      return v13
+; check:      v6 = iconst.i32 126
+; check:      v12 = iadd.i32 v0, v6
+; check:      return v12
 ; check:   block2:
-; check:      v15 = iadd.i32 v0, v1
-; check:      return v15
-
+; check:      v14 = iadd.i32 v0, v1
+; check:      return v14

cranelift/filetests/filetests/egraph/shifts.clif

@@ -651,9 +651,9 @@ block0(v0: i8):
     return v4
 }
 
-; check: v11 = iconst.i8 2
-; check: v13 = rotr v0, v11  ; v11 = 2
-; check: return v13
+; check: v6 = iconst.i8 2
+; check: v12 = rotr v0, v6  ; v6 = 2
+; check: return v12
 
 function %rotr_rotr_add(i8, i8, i8) -> i8 {
 block0(v0: i8, v1: i8, v2: i8):
@@ -675,9 +675,9 @@ block0(v0: i8):
     return v4
 }
 
-; check: v11 = iconst.i8 2
-; check: v13 = rotl v0, v11  ; v11 = 2
-; check: return v13
+; check: v6 = iconst.i8 2
+; check: v12 = rotl v0, v6  ; v6 = 2
+; check: return v12
 
 function %rotl_rotl_add(i8, i8, i8) -> i8 {
 block0(v0: i8, v1: i8, v2: i8):