From 3dc47b8161f681baef2be776056fa9cc23a8811d Mon Sep 17 00:00:00 2001 From: Robin Voetter Date: Mon, 4 Oct 2021 00:22:03 +0200 Subject: [PATCH] Apply new big int wrap/saturate to Value.zig --- lib/std/math/big/int.zig | 2 +- src/value.zig | 82 +++++++++++++++++++++++++++------------- 2 files changed, 56 insertions(+), 28 deletions(-) diff --git a/lib/std/math/big/int.zig b/lib/std/math/big/int.zig index bc19b652d8..4d778f1d22 100644 --- a/lib/std/math/big/int.zig +++ b/lib/std/math/big/int.zig @@ -2738,7 +2738,7 @@ pub fn llcmp(a: []const Limb, b: []const Limb) i8 { /// The result is computed modulo `r.len`. When `r.len >= a.len + b.len`, no overflow occurs. fn llmulaccLong(comptime op: AccOp, r: []Limb, a: []const Limb, b: []const Limb) void { @setRuntimeSafety(debug_safety); - assert(r.len >= a.len + b.len); + assert(r.len >= a.len); assert(a.len >= b.len); var i: usize = 0; diff --git a/src/value.zig b/src/value.zig index 0815c241e4..f5d7b8b05e 100644 --- a/src/value.zig +++ b/src/value.zig @@ -1669,7 +1669,7 @@ pub const Value = extern union { const rhs_bigint = rhs.toBigInt(&rhs_space); const limbs = try arena.alloc( std.math.big.Limb, - std.math.max(lhs_bigint.limbs.len, rhs_bigint.limbs.len), + std.math.big.int.calcTwosCompLimbCount(info.bits), ); var result_bigint = BigIntMutable{ .limbs = limbs, .positive = undefined, .len = undefined }; result_bigint.addWrap(lhs_bigint, rhs_bigint, info.signedness, info.bits); @@ -1701,7 +1701,7 @@ pub const Value = extern union { const rhs_bigint = rhs.toBigInt(&rhs_space); const limbs = try arena.alloc( std.math.big.Limb, - std.math.max(lhs_bigint.limbs.len, rhs_bigint.limbs.len), + std.math.big.int.calcTwosCompLimbCount(info.bits), ); var result_bigint = BigIntMutable{ .limbs = limbs, .positive = undefined, .len = undefined }; result_bigint.addSat(lhs_bigint, rhs_bigint, info.signedness, info.bits); @@ -1736,7 +1736,7 @@ pub const Value = extern union { const rhs_bigint = rhs.toBigInt(&rhs_space); const limbs = try arena.alloc( std.math.big.Limb, - std.math.max(lhs_bigint.limbs.len, rhs_bigint.limbs.len), + std.math.big.int.calcTwosCompLimbCount(info.bits), ); var result_bigint = BigIntMutable{ .limbs = limbs, .positive = undefined, .len = undefined }; result_bigint.subWrap(lhs_bigint, rhs_bigint, info.signedness, info.bits); @@ -1768,7 +1768,7 @@ pub const Value = extern union { const rhs_bigint = rhs.toBigInt(&rhs_space); const limbs = try arena.alloc( std.math.big.Limb, - std.math.max(lhs_bigint.limbs.len, rhs_bigint.limbs.len), + std.math.big.int.calcTwosCompLimbCount(info.bits), ); var result_bigint = BigIntMutable{ .limbs = limbs, .positive = undefined, .len = undefined }; result_bigint.subSat(lhs_bigint, rhs_bigint, info.signedness, info.bits); @@ -1794,19 +1794,31 @@ pub const Value = extern union { if (ty.isAnyFloat()) { return floatMul(lhs, rhs, ty, arena); } - const result = try intMul(lhs, rhs, arena); - const max = try ty.maxInt(arena, target); - if (compare(result, .gt, max, ty)) { - @panic("TODO comptime wrapping integer multiplication"); + const info = ty.intInfo(target); + + var lhs_space: Value.BigIntSpace = undefined; + var rhs_space: Value.BigIntSpace = undefined; + const lhs_bigint = lhs.toBigInt(&lhs_space); + const rhs_bigint = rhs.toBigInt(&rhs_space); + const limbs = try arena.alloc( + std.math.big.Limb, + std.math.big.int.calcTwosCompLimbCount(info.bits), + ); + var result_bigint = BigIntMutable{ .limbs = limbs, .positive = undefined, .len = undefined }; + var limbs_buffer = try arena.alloc( + std.math.big.Limb, + std.math.big.int.calcMulWrapLimbsBufferLen(info.bits, lhs_bigint.limbs.len, rhs_bigint.limbs.len, 1), + ); + defer arena.free(limbs_buffer); + result_bigint.mulWrap(lhs_bigint, rhs_bigint, info.signedness, info.bits, limbs_buffer, arena); + const result_limbs = result_bigint.limbs[0..result_bigint.len]; + + if (result_bigint.positive) { + return Value.Tag.int_big_positive.create(arena, result_limbs); + } else { + return Value.Tag.int_big_negative.create(arena, result_limbs); } - - const min = try ty.minInt(arena, target); - if (compare(result, .lt, min, ty)) { - @panic("TODO comptime wrapping integer multiplication"); - } - - return result; } /// Supports integers only; asserts neither operand is undefined. @@ -1820,19 +1832,35 @@ pub const Value = extern union { assert(!lhs.isUndef()); assert(!rhs.isUndef()); - const result = try intMul(lhs, rhs, arena); + const info = ty.intInfo(target); - const max = try ty.maxInt(arena, target); - if (compare(result, .gt, max, ty)) { - return max; + var lhs_space: Value.BigIntSpace = undefined; + var rhs_space: Value.BigIntSpace = undefined; + const lhs_bigint = lhs.toBigInt(&lhs_space); + const rhs_bigint = rhs.toBigInt(&rhs_space); + const limbs = try arena.alloc( + std.math.big.Limb, + std.math.max( + // For the saturate + std.math.big.int.calcTwosCompLimbCount(info.bits), + lhs_bigint.limbs.len + rhs_bigint.limbs.len, + ), + ); + var result_bigint = BigIntMutable{ .limbs = limbs, .positive = undefined, .len = undefined }; + var limbs_buffer = try arena.alloc( + std.math.big.Limb, + std.math.big.int.calcMulLimbsBufferLen(lhs_bigint.limbs.len, rhs_bigint.limbs.len, 1), + ); + defer arena.free(limbs_buffer); + result_bigint.mul(lhs_bigint, rhs_bigint, limbs_buffer, arena); + result_bigint.saturate(result_bigint.toConst(), info.signedness, info.bits); + const result_limbs = result_bigint.limbs[0..result_bigint.len]; + + if (result_bigint.positive) { + return Value.Tag.int_big_positive.create(arena, result_limbs); + } else { + return Value.Tag.int_big_negative.create(arena, result_limbs); } - - const min = try ty.minInt(arena, target); - if (compare(result, .lt, min, ty)) { - return min; - } - - return result; } /// Supports both floats and ints; handles undefined. @@ -2144,7 +2172,7 @@ pub const Value = extern union { const rhs_bigint = rhs.toBigInt(&rhs_space); const limbs = try allocator.alloc( std.math.big.Limb, - lhs_bigint.limbs.len + rhs_bigint.limbs.len + 1, + lhs_bigint.limbs.len + rhs_bigint.limbs.len, ); var result_bigint = BigIntMutable{ .limbs = limbs, .positive = undefined, .len = undefined }; var limbs_buffer = try allocator.alloc(