From 3473d2f8efcb448e5433931a31fb358304bb9b80 Mon Sep 17 00:00:00 2001
From: Meng Zhuo <mzh@golangcn.org>
Date: Wed, 24 Jul 2024 14:49:18 +0800
Subject: [PATCH] math: add large exact float rounding tests

This CL adds trunc,ceil,floor tests for large exact float.

Change-Id: Ib7ffec1d2d50d2ac955398a3dd0fd06d494fcf4f
Reviewed-on: https://go-review.googlesource.com/c/go/+/601095
Auto-Submit: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
---
 src/math/all_test.go | 52 +++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 47 insertions(+), 5 deletions(-)

diff --git a/src/math/all_test.go b/src/math/all_test.go
index af3c38c2a6..c253b7bc02 100644
--- a/src/math/all_test.go
+++ b/src/math/all_test.go
@@ -899,8 +899,17 @@ var vfceilSC = []float64{
 	0,
 	Inf(1),
 	NaN(),
+	1<<52 - 1,
+	1<<52 - 0.5, // largest fractional float64
+	1 << 52,
+	-1 << 52,
+	-1<<52 + 0.5, // smallest fractional float64
+	-1<<52 + 1,
+	1 << 53,
+	-1 << 53,
 }
-var ceilSC = []float64{
+
+var ceilBaseSC = []float64{
 	Inf(-1),
 	Copysign(0, -1),
 	0,
@@ -908,6 +917,39 @@ var ceilSC = []float64{
 	NaN(),
 }
 
+var ceilSC = append(ceilBaseSC,
+	1<<52-1,
+	1<<52,
+	1<<52,
+	-1<<52,
+	-1<<52+1,
+	-1<<52+1,
+	1<<53,
+	-1<<53,
+)
+
+var floorSC = append(ceilBaseSC,
+	1<<52-1,
+	1<<52-1,
+	1<<52,
+	-1<<52,
+	-1<<52,
+	-1<<52+1,
+	1<<53,
+	-1<<53,
+)
+
+var truncSC = append(ceilBaseSC,
+	1<<52-1,
+	1<<52-1,
+	1<<52,
+	-1<<52,
+	-1<<52+1,
+	-1<<52+1,
+	1<<53,
+	-1<<53,
+)
+
 var vfcopysignSC = []float64{
 	Inf(-1),
 	Inf(1),
@@ -2489,8 +2531,8 @@ func TestFloor(t *testing.T) {
 		}
 	}
 	for i := 0; i < len(vfceilSC); i++ {
-		if f := Floor(vfceilSC[i]); !alike(ceilSC[i], f) {
-			t.Errorf("Floor(%g) = %g, want %g", vfceilSC[i], f, ceilSC[i])
+		if f := Floor(vfceilSC[i]); !alike(floorSC[i], f) {
+			t.Errorf("Floor(%g) = %g, want %g", vfceilSC[i], f, floorSC[i])
 		}
 	}
 }
@@ -3034,8 +3076,8 @@ func TestTrunc(t *testing.T) {
 		}
 	}
 	for i := 0; i < len(vfceilSC); i++ {
-		if f := Trunc(vfceilSC[i]); !alike(ceilSC[i], f) {
-			t.Errorf("Trunc(%g) = %g, want %g", vfceilSC[i], f, ceilSC[i])
+		if f := Trunc(vfceilSC[i]); !alike(truncSC[i], f) {
+			t.Errorf("Trunc(%g) = %g, want %g", vfceilSC[i], f, truncSC[i])
 		}
 	}
 }
-- 
2.48.1