vector: fix tests on wasm
On wasm, calculations on float32 values are done with 64 bit precision.
This is allowed by the Go specification, only explicit conversions to
float32 have to round to 32 bit precision. The difference caused by the
additional precision accumulates over several calculations and causes
the test results to not fully match the expectations. Account for this
by giving a 0.1% tolerance.
Fixes golang/go#31281.
Change-Id: I843788f912015600a18ff3d5cf5520c60403b534
Reviewed-on: https://go-review.googlesource.com/c/image/+/171257
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Nigel Tao <nigeltao@golang.org>
diff --git a/vector/acc_test.go b/vector/acc_test.go
index d80f765..bfac42c 100644
--- a/vector/acc_test.go
+++ b/vector/acc_test.go
@@ -7,7 +7,9 @@
import (
"bytes"
"fmt"
+ "math"
"math/rand"
+ "runtime"
"testing"
)
@@ -235,7 +237,7 @@
t.Errorf("simd=%t, n=%d:\ngot: % x\nwant: % x", simd, n, got8, want8)
}
} else {
- if !uint32sEqual(got32, want32) {
+ if !uint32sMatch(got32, want32) {
t.Errorf("simd=%t, n=%d:\ngot: % x\nwant: % x", simd, n, got32, want32)
}
}
@@ -243,24 +245,52 @@
}
}
-func uint32sEqual(xs, ys []uint32) bool {
+func match(got, want float64) bool {
+ if runtime.GOARCH == "wasm" {
+ // On wasm, calculations on float32 values are done with 64 bit precision.
+ // This is allowed by the Go specification, only explicit conversions to
+ // float32 have to round to 32 bit precision. The difference caused by the
+ // additional precision accumulates over several calculations and causes
+ // the test results to not fully match the expectations. Account for this
+ // by giving a 0.1% tolerance.
+ const tolerance = 0.001
+ return math.Abs(got-want) <= math.Abs(want)*tolerance
+ }
+ return got == want
+}
+
+// sixteen is used by the calculation in the test below. It needs to be a package
+// variable so the compiler does not replace the calculation with a single constant.
+var sixteen float32 = 16
+
+// TestFloat32ArithmeticWithinTolerance checks that the precision difference of a
+// single float32 operation is within the tolerance used by the match function.
+func TestFloat32ArithmeticWithinTolerance(t *testing.T) {
+ result := float64(sixteen / 1122)
+ rounded := float64(float32(result))
+ if !match(result, rounded) {
+ t.Error("result and rounded result did not match")
+ }
+}
+
+func uint32sMatch(xs, ys []uint32) bool {
if len(xs) != len(ys) {
return false
}
for i := range xs {
- if xs[i] != ys[i] {
+ if !match(float64(xs[i]), float64(ys[i])) {
return false
}
}
return true
}
-func float32sEqual(xs, ys []float32) bool {
+func float32sMatch(xs, ys []float32) bool {
if len(xs) != len(ys) {
return false
}
for i := range xs {
- if xs[i] != ys[i] {
+ if !match(float64(xs[i]), float64(ys[i])) {
return false
}
}
@@ -452,7 +482,7 @@
return b.String()
}
- if !uint32sEqual(fxIn16, hardCodedFxIn16) {
+ if !uint32sMatch(fxIn16, hardCodedFxIn16) {
t.Errorf("height 16: got:%v\nwant:%v", dump(fxIn16), dump(hardCodedFxIn16))
}
}
@@ -469,7 +499,7 @@
return b.String()
}
- if !float32sEqual(flIn16, hardCodedFlIn16) {
+ if !float32sMatch(flIn16, hardCodedFlIn16) {
t.Errorf("height 16: got:%v\nwant:%v", dump(flIn16), dump(hardCodedFlIn16))
}
}
