gcc4 problem on netbsd-4

[start a new thread]

I wrote in article <[email protected]>:

> Okay, then we have to fix gcc4 issue on netbsd-4 before tracking
> wdc/dma issue on the HEAD. Maybe our sources might have some problem,
> rather than gcc4.
> 
> gcc4 is so aggressive on optimization and strictly requires C99
> that variables lacking volatile or statements which are invalid
> or undefined in C99 scope could be removed during optimization.
> 
> The major changes between netbsd-4 and HEAD are:
> (a) MI softintr(9) and yamt-splraiseipl merge
> (b) MI todr(9) and timecounter(9)
> (c) bus_space_handle_t type change (char * -> u_long)
> (d) caddr_t purge
> 
> I'll check sources around (a) and (b) again.

I have not confirmed, but it looks atari/dev/clock.c:delay()
in netbsd-4 may have a problem:

---
	/*
	 * Calculate ((n * TIMER_FREQ) / 1e6) using explicit assembler code so
	 * we can take advantage of the intermediate 64-bit quantity to prevent
	 * loss of significance.
	 */
	n -= 5;
	if(n < 0)
		return;
	{
	    u_int	temp;
		
	    __asm volatile ("mulul %2,%1:%0" : "=d" (n), "=d" (temp)
					       : "d" (TIMB_FREQ), "d" (n));
	    __asm volatile ("divul %1,%2:%0" : "=d" (n)
					       : "d"(1000000),"d"(temp),"0"(n));
	}
---

In this code block, variable "temp" might be passed to
__asm statements without initialization, so
it could cause unexpected too long delays.

We could just add "u_int temp = 0;" to initialize it,
but in -current that code block has been replaced with
(more human readable) C code.

Could you try this one?
http://www.ceres.dti.ne.jp/~tsutsui/netbsd/netbsd-ATARITT-4.0_STABLE-20081231.gz
http://www.ceres.dti.ne.jp/~tsutsui/netbsd/netbsd-FALCON-4.0_STABLE-20081231.gz

Index: dev/clock.c
===================================================================
RCS file: /cvsroot/src/sys/arch/atari/dev/clock.c,v
retrieving revision 1.37
diff -u -r1.37 clock.c
--- dev/clock.c	24 Dec 2005 20:06:58 -0000	1.37
+++ dev/clock.c	31 Dec 2008 17:20:18 -0000
@@ -333,10 +333,9 @@
  * Note: timer had better have been programmed before this is first used!
  */
 void
-delay(n)
-int	n;
+delay(unsigned int n)
 {
-	int	ticks, otick;
+	int	ticks, otick, remaining;
 
 	/*
 	 * Read the counter first, so that the rest of the setup overhead is
@@ -344,28 +343,25 @@
 	 */
 	otick = MFP->mf_tbdr;
 
-	/*
-	 * Calculate ((n * TIMER_FREQ) / 1e6) using explicit assembler code so
-	 * we can take advantage of the intermediate 64-bit quantity to prevent
-	 * loss of significance.
-	 */
-	n -= 5;
-	if(n < 0)
-		return;
-	{
-	    u_int	temp;
-		
-	    __asm volatile ("mulul %2,%1:%0" : "=d" (n), "=d" (temp)
-					       : "d" (TIMB_FREQ), "d" (n));
-	    __asm volatile ("divul %1,%2:%0" : "=d" (n)
-					       : "d"(1000000),"d"(temp),"0"(n));
+	if (n <= UINT_MAX / TIMB_FREQ) {
+		/*
+		 * For unsigned arithmetic, division can be replaced with
+		 * multiplication with the inverse and a shift.
+		 */
+		remaining = n * TIMB_FREQ / 1000000;
+	} else {
+		/* This is a very long delay.
+		 * Being slow here doesn't matter.
+		 */
+		remaining = (unsigned long long) n * TIMB_FREQ / 1000000;
 	}
 
-	while(n > 0) {
+	while(remaining > 0) {
 		ticks = MFP->mf_tbdr;
 		if(ticks > otick)
-			n -= TIMB_LIMIT - (ticks - otick);
-		else n -= otick - ticks;
+			remaining -= TIMB_LIMIT - (ticks - otick);
+		else
+			remaining -= otick - ticks;
 		otick = ticks;
 	}
 }
Index: include/param.h
===================================================================
RCS file: /cvsroot/src/sys/arch/atari/include/param.h,v
retrieving revision 1.30
diff -u -r1.30 param.h
--- include/param.h	11 Dec 2005 12:16:59 -0000	1.30
+++ include/param.h	31 Dec 2008 17:20:18 -0000
@@ -112,7 +112,7 @@
 
 #include <machine/intr.h>
 
-void delay __P((int));
+void delay __P((unsigned int));
 
 #define	DELAY(n)	delay(n)
 #endif	/* _KERNEL */

---