patched in assembly routines for reference

roaring/assembly.go

@@ -0,0 +1,7 @@
+package roaring
+
+func hasAsm() bool
+
+func BSFQ(memory uint64) int
+
+func POPCNTQ(memory uint64) int

roaring/assembly_amd64.s

@@ -0,0 +1,21 @@
+#include "textflag.h"
+
+TEXT ·hasAsm(SB),4,$0
+	MOVQ $1, AX
+	CPUID
+	SHRQ $23, CX
+	ANDQ $1, CX
+	MOVB CX, ret+0(FP)
+	RET
+
+TEXT ·POPCNTQ(SB),NOSPLIT,$0-8
+	MOVQ x+0(FP), BP
+	POPCNTQ BP, BX
+	MOVQ BX, ret+8(FP)
+	RET
+
+TEXT ·BSFQ(SB),NOSPLIT,$0-8
+	MOVQ x+0(FP), BP
+	BSFQ BP, BX
+	MOVQ BX, ret+8(FP)
+	RET

roaring/assembly_test.go

@@ -0,0 +1,53 @@
+package roaring
+
+import "testing"
+
+func TestBSFQ(t *testing.T) {
+	result := BSFQ(2)
+	if result != 1 {
+		t.Fatalf("BSF INCORRECT: %d", result)
+	}
+}
+
+func TestBSFQ_CompareGo(t *testing.T) {
+	v := uint64(1)
+	for i := 0; i < 64; i++ {
+		if BSFQ(v) != trailingZeroN(v) {
+			t.Fatalf("BSF INCORRECT: %d %d", BSFQ(v), trailingZeroN(v))
+		}
+		if v == 0 {
+			v = 1
+		} else {
+			v *= 2
+		}
+	}
+	/*
+		if bsfq(0) != trailingZeroN(0) {
+			fmt.Println(bsfq(0))
+			t.Fatalf("BSF INCORRECT")
+		}
+	*/
+}
+func BenchmarkBSF(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		BSFQ(uint64(i))
+	}
+}
+
+func BenchmarkTrailingZeroN(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		trailingZeroN(uint64(i))
+	}
+}
+
+func BenchmarkPOPCNTQ(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		POPCNTQ(uint64(i))
+	}
+}
+
+func BenchmarkPopcount(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		popcount(uint64(i))
+	}
+}