runtime: unify fastrand1 and fastrand2

C and Go calling conventions are now compatible, so we
don't need two versions of this function.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/139080043

src/pkg/runtime/alg.go

@@ -111,7 +111,7 @@ func f32hash(p unsafe.Pointer, s, h uintptr) uintptr {
 	case f == 0:
 		return c1 * (c0 ^ h) // +0, -0
 	case f != f:
-		return c1 * (c0 ^ h ^ uintptr(fastrand2())) // any kind of NaN
+		return c1 * (c0 ^ h ^ uintptr(fastrand1())) // any kind of NaN
 	default:
 		return memhash(p, 4, h)
 	}
@@ -123,7 +123,7 @@ func f64hash(p unsafe.Pointer, s, h uintptr) uintptr {
 	case f == 0:
 		return c1 * (c0 ^ h) // +0, -0
 	case f != f:
-		return c1 * (c0 ^ h ^ uintptr(fastrand2())) // any kind of NaN
+		return c1 * (c0 ^ h ^ uintptr(fastrand1())) // any kind of NaN
 	default:
 		return memhash(p, 8, h)
 	}

src/pkg/runtime/asm_386.s

@@ -2283,7 +2283,7 @@ TEXT runtime·duffcopy(SB), NOSPLIT, $0-0
 TEXT runtime·timenow(SB), NOSPLIT, $0-0
 	JMP	time·now(SB)
 
-TEXT runtime·fastrand2(SB), NOSPLIT, $0-4
+TEXT runtime·fastrand1(SB), NOSPLIT, $0-4
 	get_tls(CX)
 	MOVL	g(CX), AX
 	MOVL	g_m(AX), AX

src/pkg/runtime/asm_amd64.s

@@ -2335,7 +2335,7 @@ TEXT runtime·duffcopy(SB), NOSPLIT, $0-0
 TEXT runtime·timenow(SB), NOSPLIT, $0-0
 	JMP	time·now(SB)
 
-TEXT runtime·fastrand2(SB), NOSPLIT, $0-4
+TEXT runtime·fastrand1(SB), NOSPLIT, $0-4
 	get_tls(CX)
 	MOVQ	g(CX), AX
 	MOVQ	g_m(AX), AX

src/pkg/runtime/asm_amd64p32.s

@@ -1208,7 +1208,7 @@ eqret:
 TEXT runtime·timenow(SB), NOSPLIT, $0-0
 	JMP	time·now(SB)
 
-TEXT runtime·fastrand2(SB), NOSPLIT, $0-4
+TEXT runtime·fastrand1(SB), NOSPLIT, $0-4
 	get_tls(CX)
 	MOVL	g(CX), AX
 	MOVL	g_m(AX), AX

src/pkg/runtime/asm_arm.s

@@ -1259,7 +1259,7 @@ TEXT runtime·duffcopy(SB), NOSPLIT, $0-0
 	MOVW.P	R0, 4(R2)
 	RET
 
-TEXT runtime·fastrand2(SB), NOSPLIT, $-4-4
+TEXT runtime·fastrand1(SB), NOSPLIT, $-4-4
 	MOVW	g_m(g), R1
 	MOVW	m_fastrand(R1), R0
 	ADD.S	R0, R0

src/pkg/runtime/hashmap.go

@@ -219,7 +219,7 @@ func makemap(t *maptype, hint int64) *hmap {
 	h.count = 0
 	h.B = B
 	h.flags = 0
-	h.hash0 = fastrand2()
+	h.hash0 = fastrand1()
 	h.buckets = buckets
 	h.oldbuckets = nil
 	h.nevacuate = 0
@@ -568,7 +568,7 @@ func mapiterinit(t *maptype, h *hmap, it *hiter) {
 
 	// iterator state
 	it.bucket = 0
-	it.offset = uint8(fastrand2() & (bucketCnt - 1))
+	it.offset = uint8(fastrand1() & (bucketCnt - 1))
 	it.done = false
 	it.bptr = nil
 

src/pkg/runtime/malloc.go

@@ -387,7 +387,7 @@ func profilealloc(mp *m, x unsafe.Pointer, size uintptr) {
 		if rate > 0x3fffffff { // make 2*rate not overflow
 			rate = 0x3fffffff
 		}
-		next := int32(fastrand2()) % (2 * int32(rate))
+		next := int32(fastrand1()) % (2 * int32(rate))
 		// Subtract the "remainder" of the current allocation.
 		// Otherwise objects that are close in size to sampling rate
 		// will be under-sampled, because we consistently discard this remainder.

src/pkg/runtime/runtime.c

@@ -265,19 +265,6 @@ runtime·check(void)
 		runtime·throw("FixedStack is not power-of-2");
 }
 
-uint32
-runtime·fastrand1(void)
-{
-	uint32 x;
-
-	x = g->m->fastrand;
-	x += x;
-	if(x & 0x80000000L)
-		x ^= 0x88888eefUL;
-	g->m->fastrand = x;
-	return x;
-}
-
 static Mutex ticksLock;
 static int64 ticks;
 

src/pkg/runtime/select.go

@@ -226,7 +226,7 @@ func selectgoImpl(sel *_select) (uintptr, uint16) {
 	}
 	for i := 1; i < int(sel.ncase); i++ {
 		o := pollorder[i]
-		j := int(fastrand2()) % (i + 1)
+		j := int(fastrand1()) % (i + 1)
 		pollorder[i] = pollorder[j]
 		pollorder[j] = o
 	}

src/pkg/runtime/stubs.go

@@ -101,9 +101,6 @@ func racemalloc(p unsafe.Pointer, size uintptr)
 //go:noescape
 func memmove(to unsafe.Pointer, from unsafe.Pointer, n uintptr)
 
-// in asm_*.s
-func fastrand2() uint32
-
 const (
 	concurrentSweep = true
 )