Module Name: src
Committed By: matt
Date: Thu Jul 12 17:23:02 UTC 2012
Modified Files:
src/sys/arch/arm/include: byte_swap.h
Log Message:
Use __builtin_constant_p so that we only emit asm when
the expression is not a constant.
To generate a diff of this commit:
cvs rdiff -u -r1.8 -r1.9 src/sys/arch/arm/include/byte_swap.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/arm/include/byte_swap.h
diff -u src/sys/arch/arm/include/byte_swap.h:1.8 src/sys/arch/arm/include/byte_swap.h:1.9
--- src/sys/arch/arm/include/byte_swap.h:1.8 Mon Apr 28 20:23:14 2008
+++ src/sys/arch/arm/include/byte_swap.h Thu Jul 12 17:23:02 2012
@@ -1,4 +1,4 @@
-/* $NetBSD: byte_swap.h,v 1.8 2008/04/28 20:23:14 martin Exp $ */
+/* $NetBSD: byte_swap.h,v 1.9 2012/07/12 17:23:02 matt Exp $ */
/*-
* Copyright (c) 1997, 1999, 2002 The NetBSD Foundation, Inc.
@@ -40,16 +40,20 @@ __BEGIN_DECLS
static __inline uint32_t
__byte_swap_u32_variable(uint32_t v)
{
-#ifdef _ARM_ARCH_6
- __asm("rev\t%0, %1" : "=r" (v) : "0" (v));
-#else
uint32_t t1;
+#ifdef _ARM_ARCH_6
+ if (!__builtin_constant_p(v)) {
+ __asm("rev\t%0, %1" : "=r" (v) : "0" (v));
+ return v;
+ }
+#endif
+
t1 = v ^ ((v << 16) | (v >> 16));
t1 &= 0xff00ffffU;
v = (v >> 8) | (v << 24);
v ^= (t1 >> 8);
-#endif
+
return (v);
}
@@ -59,18 +63,23 @@ __byte_swap_u16_variable(uint16_t v)
{
#ifdef _ARM_ARCH_6
- __asm("rev16\t%0, %1" : "=r" (v) : "0" (v));
+ if (!__builtin_constant_p(v)) {
+ __asm("rev16\t%0, %1" : "=r" (v) : "0" (v));
+ return v;
+ }
#elif !defined(__thumb__)
- __asm volatile(
- "mov %0, %1, ror #8\n"
- "orr %0, %0, %0, lsr #16\n"
- "bic %0, %0, %0, lsl #16"
- : "=r" (v)
- : "0" (v));
-#else
+ if (!__builtin_constant_p(v)) {
+ __asm volatile(
+ "mov %0, %1, ror #8\n"
+ "orr %0, %0, %0, lsr #16\n"
+ "bic %0, %0, %0, lsl #16"
+ : "=&r" (v)
+ : "0" (v));
+ return (v);
+ }
+#endif
v &= 0xffff;
v = (v >> 8) | (v << 8);
-#endif
return (v);
}
