Handle out of range values for mod operator

packages/compiler/src/encoding.ts

@@ -96,10 +96,11 @@ export const op = {
    * Numeric Instructions
    * https://webassembly.github.io/spec/core/binary/instructions.html#numeric-instructions
    */
-  i32_const: (i: number) => [0x41, ...signedLEB128(i)],
-  // i64_const: 0x42,
+  // TODO: Add bounds checking
+  i32_const: (n: number) => [0x41, ...signedLEB128(n)],
+  i64_const: (n: number) => [0x42, ...signedLEB128(n)],
   // f32_const: 0x43,
-  f64_const: (i: number) => [0x44, ...encodef64(i)],
+  f64_const: (n: number) => [0x44, ...encodef64(n)],
 
   i32_eqz: 0x45,
   // i32_eq: 0x46,
@@ -114,6 +115,7 @@ export const op = {
   // i32_ge_u: 0x4f,
 
   // [0x50...0x5a] i64
+  i64_ne: 0x52,
   // [0x5b...0x60] f32
 
   f64_eq: 0x61,
@@ -164,6 +166,9 @@ export const op = {
   i64_trunc_s_f64: 0xb0,
   f64_convert_i64_s: 0xb9,
   f64_convert_i32_s: 0xb7,
+
+  i64_trunc_f64_s: 0xb0,
+  i64_trunc_f64_u: 0xb1,
 };
 
 // https://webassembly.github.io/spec/core/binary/instructions.html#binary-blocktype

packages/compiler/src/wasmFunctions.ts

@@ -2,6 +2,39 @@ import { op, VAL_TYPE, IS_NOT_ZEROISH, EPSILON, BLOCK } from "./encoding.js";
 import { FunctionDefinition } from "./types.js";
 import { BUFFER_SIZE } from "./constants.js";
 
+// Minimum value that x87 would treat as out of range for conversion
+// from float to int.
+const MIN_OUT_OF_RANGE = op.f64_const(Math.pow(2, 31));
+// Arbitrary value that x87 uses when trying to convert an out of range, or NaN,
+// float to an int.
+
+const INDETERMINATE = op.f64_const(Math.pow(2, 31));
+
+/**
+ * Reimplements the details of how x87 handles out of range values in the `fist`
+ * instruction.
+ *
+ * Expects a local argument offset and leaves an i64 value on the stack. We use
+ * i64 since teh indeterminate value is 2^31, which is just out of the range of
+ * i32.
+ *
+ * See https://godbolt.org/z/rjf769E3n for some examples
+ */
+function localGetAsBoundedPositiveInt(argOffset: number): number[] {
+  return [
+    ...op.local_get(argOffset),
+    ...MIN_OUT_OF_RANGE,
+    op.f64_lt,
+    ...op.if(BLOCK.f64),
+    ...op.local_get(argOffset),
+    op.f64_abs,
+    op.else,
+    ...INDETERMINATE,
+    op.end,
+    op.i64_trunc_f64_s,
+  ];
+}
+
 export const localFuncMap: { [functionName: string]: FunctionDefinition } = {
   sqr: {
     args: [VAL_TYPE.f64],
@@ -53,20 +86,18 @@ export const localFuncMap: { [functionName: string]: FunctionDefinition } = {
   mod: {
     args: [VAL_TYPE.f64, VAL_TYPE.f64],
     returns: [VAL_TYPE.f64],
-    localVariables: [VAL_TYPE.i32],
-    // TODO: Simplify all this type coercion
+    localVariables: [VAL_TYPE.i64],
+    // Tuned to match https://github.com/WACUP/vis_milk2/blob/de9625a89e724afe23ed273b96b8e48496095b6c/ns-eel2/asm-nseel-x86-gcc.c#L507-L531
     binary: [
-      ...op.local_get(1),
-      op.i32_trunc_f64_s,
+      ...localGetAsBoundedPositiveInt(1),
       ...op.local_tee(2),
-      ...op.i32_const(0),
-      op.i32_ne,
+      ...op.i64_const(0),
+      op.i64_ne,
       ...op.if(BLOCK.f64),
-      ...op.local_get(0),
-      op.i32_trunc_f64_s,
+      ...localGetAsBoundedPositiveInt(0),
       ...op.local_get(2),
-      op.i32_rem_s,
-      op.f64_convert_i32_s,
+      op.i64_rem_s,
+      op.f64_convert_i64_s,
       op.else,
       ...op.f64_const(0),
       op.end,

packages/compiler/tools/testCases.ts

@@ -1,4 +1,11 @@
 const testCases: [string, string, number][] = [
+  // https://github.com/captbaritone/eel-wasm/issues/61
+  ["Mod with NaN in dividend", "g = asin(2) % 2;", 0], // The indeterminate is even
+  ["Mod with large even value in dividend", "g = 56991359368.52679 % 2;", 0], // The indeterminate is even
+  ["Mod with large odd value in dividend", "g = 56991359367.52679 % 2;", 0], // The indeterminate is even
+  ["Mod with large even value in divisor", "g = 300 % 56991359368.52679;", 300],
+  ["Mod with large odd value in divisor", "g = 300 % 56991359367.52679;", 300],
+  ["Mod with NaN in divisor", "g = 300 % asin(2);", 300],
   ["Expressions", "g = ((6- -7)+ 3);", 16],
   ["Number", "g = 5;", 5],
   ["Number with decimal", "g = 5.5;", 5.5],
@@ -39,18 +46,19 @@ const testCases: [string, string, number][] = [
   ["Cos", "g = cos(10);", Math.cos(10)],
   ["Tan", "g = tan(10);", Math.tan(10)],
   ["Asin", "g = asin(0.5);", Math.asin(0.5)],
+  ["Asin", "g = asin(2);", NaN],
   ["Acos", "g = acos(0.5);", Math.acos(0.5)],
   ["Atan", "g = atan(0.5);", Math.atan(0.5)],
   ["Atan2", "g = atan2(1, 1);", Math.atan2(1, 1)],
   ["Assign to globals", "g = 10;", 10],
   ["Read globals", "g = x;", 10],
   ["Multiple statements", "g = 10; g = 20;", 20],
   ["Multiple statements expression", "(g = 10; g = 20;);", 20],
-  ["Multiple statements expression implcit return", "g = (0; 20 + 5;);", 25],
+  ["Multiple statements expression implicit return", "g = (0; 20 + 5;);", 25],
   ["if", "g = if(0, 20, 10);", 10],
   ["if", "g = if(0, 20, 10);", 10],
-  ["if does short-circit (consiquent)", "if(0, (g = 10;), 10);", 0],
-  ["if does short-circit (alternate)", "if(1, (10), (g = 10;));", 0],
+  ["if does short-circuit (consequent)", "if(0, (g = 10;), 10);", 0],
+  ["if does short-circuit (alternate)", "if(1, (10), (g = 10;));", 0],
   ["above (true)", "g = above(10, 4);", 1],
   ["above (false)", "g = above(4, 10);", 0],
   ["below (true)", "g = below(4, 10);", 1],