[release-branch.go1.9] bytes, strings: fix comparison of long byte slices on s390x
The existing implementation of bytes.Compare on s390x doesn't work properly for slices longer
than 256 elements. This change fixes that. Added tests for long strings and slices of bytes.
Fixes #26118
Change-Id: If6d8b68ee6dbcf99a24f867a1d3438b1f208954f
Reviewed-on: https://go-review.googlesource.com/121495
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-on: https://go-review.googlesource.com/124137
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/src/bytes/compare_test.go b/src/bytes/compare_test.go
index 35088a1..3e33c27 100644
--- a/src/bytes/compare_test.go
+++ b/src/bytes/compare_test.go
@@ -6,6 +6,7 @@
import (
. "bytes"
+ "internal/testenv"
"testing"
)
@@ -58,10 +59,20 @@
}
func TestCompareBytes(t *testing.T) {
- n := 128
+ lengths := make([]int, 0) // lengths to test in ascending order
+ for i := 0; i <= 128; i++ {
+ lengths = append(lengths, i)
+ }
+ lengths = append(lengths, 256, 512, 1024, 1333, 4095, 4096, 4097)
+
+ if !testing.Short() || testenv.Builder() != "" {
+ lengths = append(lengths, 65535, 65536, 65537, 99999)
+ }
+
+ n := lengths[len(lengths)-1]
a := make([]byte, n+1)
b := make([]byte, n+1)
- for len := 0; len < 128; len++ {
+ for _, len := range lengths {
// randomish but deterministic data. No 0 or 255.
for i := 0; i < len; i++ {
a[i] = byte(1 + 31*i%254)
diff --git a/src/runtime/asm_s390x.s b/src/runtime/asm_s390x.s
index 20e740b..686e3db 100644
--- a/src/runtime/asm_s390x.s
+++ b/src/runtime/asm_s390x.s
@@ -1004,6 +1004,8 @@
BGT gt
BLT lt
SUB $256, R8
+ MOVD $256(R3), R3
+ MOVD $256(R5), R5
CMP R8, $256
BGT loop
tail:
diff --git a/src/strings/compare_test.go b/src/strings/compare_test.go
index bc12e42..712e5a7 100644
--- a/src/strings/compare_test.go
+++ b/src/strings/compare_test.go
@@ -8,6 +8,7 @@
// Benchmarks omitted since the underlying implementation is identical.
import (
+ "internal/testenv"
. "strings"
"testing"
)
@@ -52,10 +53,20 @@
}
func TestCompareStrings(t *testing.T) {
- n := 128
+ lengths := make([]int, 0) // lengths to test in ascending order
+ for i := 0; i <= 128; i++ {
+ lengths = append(lengths, i)
+ }
+ lengths = append(lengths, 256, 512, 1024, 1333, 4095, 4096, 4097)
+
+ if !testing.Short() || testenv.Builder() != "" {
+ lengths = append(lengths, 65535, 65536, 65537, 99999)
+ }
+
+ n := lengths[len(lengths)-1]
a := make([]byte, n+1)
b := make([]byte, n+1)
- for len := 0; len < 128; len++ {
+ for _, len := range lengths {
// randomish but deterministic data. No 0 or 255.
for i := 0; i < len; i++ {
a[i] = byte(1 + 31*i%254)
