From: Paul Mackerras <paulus@samba.org>
Date: Fri, 18 Apr 2008 04:26:08 +0000 (+1000)
Subject: [POWERPC] Optimize fls64() on 64-bit processors
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=9f264be6101c42cb9e471c58322fb83a5cde1461;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git

[POWERPC] Optimize fls64() on 64-bit processors

64-bit powerpc processors can find the leftmost 1 bit in a 64-bit
doubleword in one instruction, so use that rather than using the
generic fls64(), which does two 32-bit fls() calls.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---

diff --git a/include/asm-powerpc/bitops.h b/include/asm-powerpc/bitops.h
index 36c8f3a4379..a99a7492947 100644
--- a/include/asm-powerpc/bitops.h
+++ b/include/asm-powerpc/bitops.h
@@ -312,7 +312,24 @@ static __inline__ int fls(unsigned int x)
 	asm ("cntlzw %0,%1" : "=r" (lz) : "r" (x));
 	return 32 - lz;
 }
+
+/*
+ * 64-bit can do this using one cntlzd (count leading zeroes doubleword)
+ * instruction; for 32-bit we use the generic version, which does two
+ * 32-bit fls calls.
+ */
+#ifdef __powerpc64__
+static __inline__ int fls64(__u64 x)
+{
+	int lz;
+
+	asm ("cntlzd %0,%1" : "=r" (lz) : "r" (x));
+	return 64 - lz;
+}
+#else
 #include <asm-generic/bitops/fls64.h>
+#endif /* __powerpc64__ */
+
 #include <asm-generic/bitops/hweight.h>
 #include <asm-generic/bitops/find.h>