From 590400071b0549d37f6b760870fb854da6bf2294 Mon Sep 17 00:00:00 2001
From: Zalim Bashorov <zalim.bashorov@jetbrains.com>
Date: Tue, 18 Jul 2023 00:00:59 +0200
Subject: [PATCH] [Wasm] Define canonical representation for NaNs explicitly
 instead of depending on Kotlin's one

Surprisingly with `Float.NaN.toRawBits()` you can observe different values,
which can lead to different wat files for the same input.
---
 .../kotlin/wasm/ir/convertors/WasmIrToText.kt          | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/wasm/wasm.ir/src/org/jetbrains/kotlin/wasm/ir/convertors/WasmIrToText.kt b/wasm/wasm.ir/src/org/jetbrains/kotlin/wasm/ir/convertors/WasmIrToText.kt
index a239cd8ad08..4ad6e8e8978 100644
--- a/wasm/wasm.ir/src/org/jetbrains/kotlin/wasm/ir/convertors/WasmIrToText.kt
+++ b/wasm/wasm.ir/src/org/jetbrains/kotlin/wasm/ir/convertors/WasmIrToText.kt
@@ -146,7 +146,6 @@ class WasmIrToText : SExpressionBuilder() {
         }
     }
 
-
     private fun f32Str(x: WasmImmediate.ConstF32): String {
         val bits = x.rawBits.toInt()
         val v = Float.fromBits(bits)
@@ -156,7 +155,8 @@ class WasmIrToText : SExpressionBuilder() {
             } else {
                 "-"
             }
-            if (bits != Float.NaN.toRawBits()) {
+
+            if (bits != F32_CANON_NAN) {
                 val customPayload = bits and 0x7fffff
                 "${sign}nan:0x${customPayload.toString(16)}"
             } else {
@@ -182,7 +182,7 @@ class WasmIrToText : SExpressionBuilder() {
             } else {
                 "-"
             }
-            if (bits != Double.NaN.toRawBits()) {
+            if (bits != F64_CANON_NAN) {
                 val customPayload = bits and 0xfffffffffffff
                 "${sign}nan:0x${customPayload.toString(16)}"
             } else {
@@ -585,3 +585,7 @@ fun isValidWatIdentifierChar(c: Char): Boolean =
             //  permitted identifiers: '?', '<'
             || c in "!#$%&′*+-./:<=>?@\\^_`|~"
             || c in "$.@_"
+
+// https://webassembly.github.io/spec/core/syntax/values.html#floating-point
+private const val F32_CANON_NAN = 0x7FC0_0000
+private const val F64_CANON_NAN = 0x7FF8_0000_0000_0000L