svn commit: r345520 - head/sys/powerpc/aim

[Justin Hibbits]

Author: jhibbits
Date: Tue Mar 26 02:53:35 2019
New Revision: 345520
URL: https://svnweb.freebsd.org/changeset/base/345520

Log:
  powerpc64: Micro-optimize moea64 native pmap tlbie
  
  * Cache moea64_need_lock in a local variable; gcc generates slightly better
    code this way, it doesn't need to reload the value from memory each read.
  * VPN cropping is only needed on PowerPC ISA 2.02 and older cores, a subset
    of those that need serialization, so move this under the need_lock check,
    so those that don't need the lock don't even need to check this.

Modified:
  head/sys/powerpc/aim/moea64_native.c

Modified: head/sys/powerpc/aim/moea64_native.c
==============================================================================
--- head/sys/powerpc/aim/moea64_native.c	Tue Mar 26 02:45:23 2019	(r345519)
+++ head/sys/powerpc/aim/moea64_native.c	Tue Mar 26 02:53:35 2019	(r345520)
@@ -146,18 +146,19 @@ TLBIE(uint64_t vpn) {
 #endif
 
 	static volatile u_int tlbie_lock = 0;
+	bool need_lock = moea64_need_lock;
 
 	vpn <<= ADDR_PIDX_SHFT;
 
 	/* Hobo spinlock: we need stronger guarantees than mutexes provide */
-	if (moea64_need_lock) {
+	if (need_lock) {
 		while (!atomic_cmpset_int(&tlbie_lock, 0, 1));
 		isync(); /* Flush instruction queue once lock acquired */
+
+		if (moea64_crop_tlbie)
+			vpn &= ~(0xffffULL << 48);
 	}
 
-	if (moea64_crop_tlbie)
-		vpn &= ~(0xffffULL << 48);
-
 #ifdef __powerpc64__
 	/*
 	 * Explicitly clobber r0.  The tlbie instruction has two forms: an old
@@ -196,7 +197,7 @@ TLBIE(uint64_t vpn) {
 #endif
 
 	/* No barriers or special ops -- taken care of by ptesync above */
-	if (moea64_need_lock)
+	if (need_lock)
 		tlbie_lock = 0;
 }