From e7f485bfdb1942312c88546cd05d7f488ddc883a Mon Sep 17 00:00:00 2001
From: Robin Templeton <robin@igalia.com>
Date: Sun, 8 Jul 2018 21:12:00 +0300
Subject: [PATCH] bug 1471134 - Part 1: Define methods for basic BigInt
 arithmetic. r=Waldo

---
 js/src/js.msg            |   1 +
 js/src/vm/BigIntType.cpp | 110 +++++++++++++++++++++++++++++++++++++++
 js/src/vm/BigIntType.h   |   7 +++
 3 files changed, 118 insertions(+)

diff --git a/js/src/js.msg b/js/src/js.msg
index 98b370579997..181866a3d9df 100644
--- a/js/src/js.msg
+++ b/js/src/js.msg
@@ -652,6 +652,7 @@ MSG_DEF(JSMSG_RESPONSE_ALREADY_CONSUMED,                 0, JSEXN_TYPEERR,  "Res
 // BigInt
 MSG_DEF(JSMSG_BIGINT_TO_NUMBER, 0, JSEXN_TYPEERR, "can't convert BigInt to number")
 MSG_DEF(JSMSG_NUMBER_TO_BIGINT, 0, JSEXN_RANGEERR, "can't convert non-finite number to BigInt")
+MSG_DEF(JSMSG_BIGINT_TOO_LARGE, 0, JSEXN_RANGEERR, "BigInt is too large to allocate")
 MSG_DEF(JSMSG_BIGINT_DIVISION_BY_ZERO, 0, JSEXN_RANGEERR, "BigInt division by zero")
 MSG_DEF(JSMSG_BIGINT_NEGATIVE_EXPONENT, 0, JSEXN_RANGEERR, "BigInt negative exponent")
 MSG_DEF(JSMSG_BIGINT_INVALID_SYNTAX, 0, JSEXN_SYNTAXERR, "invalid BigInt syntax")
diff --git a/js/src/vm/BigIntType.cpp b/js/src/vm/BigIntType.cpp
index 41e0619c3af3..45c281b74fe0 100644
--- a/js/src/vm/BigIntType.cpp
+++ b/js/src/vm/BigIntType.cpp
@@ -171,6 +171,116 @@ BigInt::copy(JSContext* cx, HandleBigInt x)
     return bi;
 }
 
+// BigInt proposal section 1.1.7
+BigInt*
+BigInt::add(JSContext* cx, HandleBigInt x, HandleBigInt y)
+{
+    BigInt* z = create(cx);
+    if (!z)
+        return nullptr;
+    mpz_add(z->num_, x->num_, y->num_);
+    return z;
+}
+
+// BigInt proposal section 1.1.8
+BigInt*
+BigInt::sub(JSContext* cx, HandleBigInt x, HandleBigInt y)
+{
+    BigInt* z = create(cx);
+    if (!z)
+        return nullptr;
+    mpz_sub(z->num_, x->num_, y->num_);
+    return z;
+}
+
+// BigInt proposal section 1.1.4
+BigInt*
+BigInt::mul(JSContext* cx, HandleBigInt x, HandleBigInt y)
+{
+    BigInt* z = create(cx);
+    if (!z)
+        return nullptr;
+    mpz_mul(z->num_, x->num_, y->num_);
+    return z;
+}
+
+// BigInt proposal section 1.1.5
+BigInt*
+BigInt::div(JSContext* cx, HandleBigInt x, HandleBigInt y)
+{
+    // Step 1.
+    if (mpz_size(y->num_) == 0) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+                                  JSMSG_BIGINT_DIVISION_BY_ZERO);
+        return nullptr;
+    }
+
+    // Steps 2-3.
+    BigInt* z = create(cx);
+    if (!z)
+        return nullptr;
+    mpz_tdiv_q(z->num_, x->num_, y->num_);
+    return z;
+}
+
+// BigInt proposal section 1.1.6
+BigInt*
+BigInt::mod(JSContext* cx, HandleBigInt x, HandleBigInt y)
+{
+    // Step 1.
+    if (mpz_size(y->num_) == 0) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+                                  JSMSG_BIGINT_DIVISION_BY_ZERO);
+        return nullptr;
+    }
+
+    // Steps 2-4.
+    BigInt* z = create(cx);
+    if (!z)
+        return nullptr;
+    mpz_tdiv_r(z->num_, x->num_, y->num_);
+    return z;
+}
+
+// BigInt proposal section 1.1.3
+BigInt*
+BigInt::pow(JSContext* cx, HandleBigInt x, HandleBigInt y)
+{
+    // Step 1.
+    if (mpz_sgn(y->num_) < 0) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+                                  JSMSG_BIGINT_NEGATIVE_EXPONENT);
+        return nullptr;
+    }
+
+    // Throw a RangeError if the exponent is too large.
+    if (!mpz_fits_uint_p(y->num_)) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+                                  JSMSG_BIGINT_TOO_LARGE);
+        return nullptr;
+    }
+    unsigned long int power = mpz_get_ui(y->num_);
+
+    // Steps 2-3.
+    BigInt* z = create(cx);
+    if (!z)
+        return nullptr;
+
+    mpz_pow_ui(z->num_, x->num_, power);
+    return z;
+}
+
+// BigInt proposal section 1.1.1
+BigInt*
+BigInt::neg(JSContext* cx, HandleBigInt x)
+{
+    BigInt* res = create(cx);
+    if (!res)
+        return nullptr;
+    mpz_neg(res->num_, x->num_);
+    return res;
+}
+
 // BigInt proposal section 7.3
 BigInt*
 js::ToBigInt(JSContext* cx, HandleValue val)
diff --git a/js/src/vm/BigIntType.h b/js/src/vm/BigIntType.h
index b3b5fcefcd7e..361de8e70e75 100644
--- a/js/src/vm/BigIntType.h
+++ b/js/src/vm/BigIntType.h
@@ -73,6 +73,13 @@ class BigInt final : public js::gc::TenuredCell
     static void init();
 
     static BigInt* copy(JSContext* cx, Handle<BigInt*> x);
+    static BigInt* add(JSContext* cx, Handle<BigInt*> x, Handle<BigInt*> y);
+    static BigInt* sub(JSContext* cx, Handle<BigInt*> x, Handle<BigInt*> y);
+    static BigInt* mul(JSContext* cx, Handle<BigInt*> x, Handle<BigInt*> y);
+    static BigInt* div(JSContext* cx, Handle<BigInt*> x, Handle<BigInt*> y);
+    static BigInt* mod(JSContext* cx, Handle<BigInt*> x, Handle<BigInt*> y);
+    static BigInt* pow(JSContext* cx, Handle<BigInt*> x, Handle<BigInt*> y);
+    static BigInt* neg(JSContext* cx, Handle<BigInt*> x);
 
     static double numberValue(BigInt* x);
     static JSLinearString* toString(JSContext* cx, BigInt* x, uint8_t radix);