The previous commit, roughly one and a half years ago removed the

branch prediction optimization for LINT, because the kernel was too
large. This commit now removes it altogether since it causes build
failures for GENERIC kernels and the various applicable trends are
such that one can expect that it these failure will cause more
problems than they're worth in the future. These trends include:
1. Alpha was demoted from tier 1 to tier 2 due to lack of active
   support. The number of people willing to fix build breakages
   is not likely to increase and those developers that do have the
   gumption to test MI changes on alpha are not likely to spend
   time fixing unexpected build failures first.
2. The kernel will only increase in size. Even though stripped-down
   kernels do link without problems now, compiler optimizations (like
   inlining) and new (non-optional) functionality will likely cause
   stripped-down kernels to break in the future as well.

So, with my asbestos suit on, get rid of potential problems before
they happen.

MT5 candidate.

1 files changed, 14 insertions, 62 deletions

diff --git a/sys/alpha/include/atomic.h b/sys/alpha/include/atomic.h
index 1d1354a..599700b 100644
--- a/sys/alpha/include/atomic.h
+++ b/sys/alpha/include/atomic.h
@@ -32,18 +32,6 @@
 #include <machine/alpha_cpu.h>
 
 /*
- * Quick and dirty workaround for compiling LINT. The kernel is too
- * large to jump between sections without linker stubs/trampolines.
- */
-#ifdef COMPILING_LINT
-#define	__COLD_SECTION	"br 3f\n"
-#define	__HOT_SECTION	"3:\n"
-#else
-#define	__COLD_SECTION	".section .text3,\"ax\"\n"
-#define	__HOT_SECTION	".previous\n"
-#endif
-
-/*
  * Various simple arithmetic on memory which is atomic in the presence
  * of interrupts and SMP safe.
  */
@@ -67,10 +55,7 @@ static __inline void atomic_set_32(volatile u_int32_t *p, u_int32_t v)
 		"1:\tldl_l %0, %2\n\t"		/* load old value */
 		"bis %0, %3, %0\n\t"		/* calculate new value */
 		"stl_c %0, %1\n\t"		/* attempt to store */
-		"beq %0, 2f\n\t"		/* spin if failed */
-		__COLD_SECTION			/* improve branch prediction */
-		"2:\tbr 1b\n"			/* try again */
-		__HOT_SECTION
+		"beq %0, 1b\n"			/* spin if failed */
 		: "=&r" (temp), "=m" (*p)
 		: "m" (*p), "r" (v)
 		: "memory");
@@ -86,10 +71,7 @@ static __inline void atomic_clear_32(volatile u_int32_t *p, u_int32_t v)
 		"1:\tldl_l %0, %1\n\t"		/* load old value */
 		"bic %0, %2, %0\n\t"		/* calculate new value */
 		"stl_c %0, %1\n\t"		/* attempt to store */
-		"beq %0, 2f\n\t"		/* spin if failed */
-		__COLD_SECTION			/* improve branch prediction */
-		"2:\tbr 1b\n"			/* try again */
-		__HOT_SECTION
+		"beq %0, 1b\n"			/* spin if failed */
 		: "=&r" (temp), "+m" (*p)
 		: "r" (v)
 		: "memory");
@@ -105,10 +87,7 @@ static __inline void atomic_add_32(volatile u_int32_t *p, u_int32_t v)
 		"1:\tldl_l %0, %1\n\t"		/* load old value */
 		"addl %0, %2, %0\n\t"		/* calculate new value */
 		"stl_c %0, %1\n\t"		/* attempt to store */
-		"beq %0, 2f\n\t"		/* spin if failed */
-		__COLD_SECTION			/* improve branch prediction */
-		"2:\tbr 1b\n"			/* try again */
-		__HOT_SECTION
+		"beq %0, 1b\n"			/* spin if failed */
 		: "=&r" (temp), "+m" (*p)
 		: "r" (v)
 		: "memory");
@@ -124,10 +103,7 @@ static __inline void atomic_subtract_32(volatile u_int32_t *p, u_int32_t v)
 		"1:\tldl_l %0, %1\n\t"		/* load old value */
 		"subl %0, %2, %0\n\t"		/* calculate new value */
 		"stl_c %0, %1\n\t"		/* attempt to store */
-		"beq %0, 2f\n\t"		/* spin if failed */
-		__COLD_SECTION			/* improve branch prediction */
-		"2:\tbr 1b\n"			/* try again */
-		__HOT_SECTION
+		"beq %0, 1b\n"			/* spin if failed */
 		: "=&r" (temp), "+m" (*p)
 		: "r" (v)
 		: "memory");
@@ -144,10 +120,7 @@ static __inline u_int32_t atomic_readandclear_32(volatile u_int32_t *addr)
 		"1:\tldl_l %0,%2\n\t"	/* load current value, asserting lock */
 		"ldiq %1,0\n\t"		/* value to store */
 		"stl_c %1,%2\n\t"	/* attempt to store */
-		"beq %1,2f\n\t"		/* if the store failed, spin */
-		"br 3f\n"		/* it worked, exit */
-		"2:\tbr 1b\n"		/* *addr not updated, loop */
-		"3:\n"			/* it worked */
+		"beq %1,1b\n"		/* if the store failed, spin */
 		: "=&r"(result), "=&r"(temp), "+m" (*addr)
 		:
 		: "memory");
@@ -165,10 +138,7 @@ static __inline void atomic_set_64(volatile u_int64_t *p, u_int64_t v)
 		"1:\tldq_l %0, %1\n\t"		/* load old value */
 		"bis %0, %2, %0\n\t"		/* calculate new value */
 		"stq_c %0, %1\n\t"		/* attempt to store */
-		"beq %0, 2f\n\t"		/* spin if failed */
-		__COLD_SECTION			/* improve branch prediction */
-		"2:\tbr 1b\n"			/* try again */
-		__HOT_SECTION
+		"beq %0, 1b\n"			/* spin if failed */
 		: "=&r" (temp), "+m" (*p)
 		: "r" (v)
 		: "memory");
@@ -184,10 +154,7 @@ static __inline void atomic_clear_64(volatile u_int64_t *p, u_int64_t v)
 		"1:\tldq_l %0, %1\n\t"		/* load old value */
 		"bic %0, %2, %0\n\t"		/* calculate new value */
 		"stq_c %0, %1\n\t"		/* attempt to store */
-		"beq %0, 2f\n\t"		/* spin if failed */
-		__COLD_SECTION			/* improve branch prediction */
-		"2:\tbr 1b\n"			/* try again */
-		__HOT_SECTION
+		"beq %0, 1b\n"			/* spin if failed */
 		: "=&r" (temp), "+m" (*p)
 		: "r" (v)
 		: "memory");
@@ -203,10 +170,7 @@ static __inline void atomic_add_64(volatile u_int64_t *p, u_int64_t v)
 		"1:\tldq_l %0, %1\n\t"		/* load old value */
 		"addq %0, %2, %0\n\t"		/* calculate new value */
 		"stq_c %0, %1\n\t"		/* attempt to store */
-		"beq %0, 2f\n\t"		/* spin if failed */
-		__COLD_SECTION			/* improve branch prediction */
-		"2:\tbr 1b\n"			/* try again */
-		__HOT_SECTION
+		"beq %0, 1b\n"			/* spin if failed */
 		: "=&r" (temp), "+m" (*p)
 		: "r" (v)
 		: "memory");
@@ -222,10 +186,7 @@ static __inline void atomic_subtract_64(volatile u_int64_t *p, u_int64_t v)
 		"1:\tldq_l %0, %1\n\t"		/* load old value */
 		"subq %0, %2, %0\n\t"		/* calculate new value */
 		"stq_c %0, %1\n\t"		/* attempt to store */
-		"beq %0, 2f\n\t"		/* spin if failed */
-		__COLD_SECTION			/* improve branch prediction */
-		"2:\tbr 1b\n"			/* try again */
-		__HOT_SECTION
+		"beq %0, 1b\n"			/* spin if failed */
 		: "=&r" (temp), "+m" (*p)
 		: "r" (v)
 		: "memory");
@@ -242,10 +203,7 @@ static __inline u_int64_t atomic_readandclear_64(volatile u_int64_t *addr)
 		"1:\tldq_l %0,%2\n\t"	/* load current value, asserting lock */
 		"ldiq %1,0\n\t"		/* value to store */
 		"stq_c %1,%2\n\t"	/* attempt to store */
-		"beq %1,2f\n\t"		/* if the store failed, spin */
-		"br 3f\n"		/* it worked, exit */
-		"2:\tbr 1b\n"		/* *addr not updated, loop */
-		"3:\n"			/* it worked */
+		"beq %1,1b\n"		/* if the store failed, spin */
 		: "=&r"(result), "=&r"(temp), "+m" (*addr)
 		:
 		: "memory");
@@ -385,11 +343,8 @@ atomic_cmpset_32(volatile u_int32_t* p, u_int32_t cmpval, u_int32_t newval)
 		"beq %0, 2f\n\t"		/* exit if not equal */
 		"mov %3, %0\n\t"		/* value to store */
 		"stl_c %0, %1\n\t"		/* attempt to store */
-		"beq %0, 3f\n\t"		/* if it failed, spin */
-		"2:\n"				/* done */
-		__COLD_SECTION			/* improve branch prediction */
-		"3:\tbr 1b\n"			/* try again */
-		__HOT_SECTION
+		"beq %0, 1b\n\t"		/* if it failed, spin */
+		"2:\n"
 		: "=&r" (ret), "+m" (*p)
 		: "r" ((long)(int)cmpval), "r" (newval)
 		: "memory");
@@ -415,11 +370,8 @@ atomic_cmpset_64(volatile u_int64_t* p, u_int64_t cmpval, u_int64_t newval)
 		"beq %0, 2f\n\t"		/* exit if not equal */
 		"mov %3, %0\n\t"		/* value to store */
 		"stq_c %0, %1\n\t"		/* attempt to store */
-		"beq %0, 3f\n\t"		/* if it failed, spin */
-		"2:\n"				/* done */
-		__COLD_SECTION			/* improve branch prediction */
-		"3:\tbr 1b\n"			/* try again */
-		__HOT_SECTION
+		"beq %0, 1b\n\t"		/* if it failed, spin */
+		"2:\n"
 		: "=&r" (ret), "+m" (*p)
 		: "r" (cmpval), "r" (newval)
 		: "memory");