code review 5606048: runtime: add runtime.cputicks() and seed fastrand with it

src/pkg/runtime/asm_386.s

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 #include "zasm_GOOS_GOARCH.h"
 
 TEXT _rt0_386(SB),7,$0
         // Linux, Windows start the FPU in extended double precision.
         // Other operating systems use double precision.
         // Change to double precision to match them,
@@ skipping 506 matching lines @@
 TEXT runtime·setcallerpc(SB),7,$0
         MOVL    x+0(FP),AX              // addr of first arg
         MOVL    x+4(FP), BX
         MOVL    BX, -4(AX)              // set calling pc
         RET
 
 TEXT runtime·getcallersp(SB), 7, $0
         MOVL    sp+0(FP), AX
         RET
 
+// int64 runtime·cputicks(void), so really
+// void runtime·cputicks(int64 *ticks)
+TEXT runtime·cputicks(SB),7,$0
+        BYTE    $0x0F; BYTE $0x31;     // RDTSC; not supported by 8a
+        MOVL    ret+0(FP), DI
+        MOVL    AX, 0(DI)
+        MOVL    DX, 4(DI)
+        RET
+
 TEXT runtime·ldt0setup(SB),7,$16
         // set up ldt 7 to point at tls0
         // ldt 1 would be fine on Linux, but on OS X, 7 is as low as we can go.
         // the entry number is just a hint.  setldt will set up GS with what it used.
         MOVL    $7, 0(SP)
         LEAL    runtime·tls0(SB), AX
         MOVL    AX, 4(SP)
         MOVL    $32, 8(SP)      // sizeof(tls array)
         CALL    runtime·setldt(SB)
         RET
 
 TEXT runtime·emptyfunc(SB),0,$0
         RET
 
 TEXT runtime·abort(SB),7,$0
         INT $0x3
 
 GLOBL runtime·tls0(SB), $32