[10/10] libgcc: use __builtin_clz and __builtin_ctz in libbid
Commit Message
This patch replaces libbid's implementations of clz and ctz for 32 and
64 bits inputs which used several masks, and switches to the
corresponding builtins. This will provide a better implementation,
especially on targets with clz/ctz instructions.
2022-05-06 Christophe Lyon <christophe.lyon@arm.com>
libgcc/config/libbid/ChangeLog:
* bid_binarydecimal.c (CLZ32_MASK16): Delete.
(CLZ32_MASK8): Delete.
(CLZ32_MASK4): Delete.
(CLZ32_MASK2): Delete.
(CLZ32_MASK1): Delete.
(clz32_nz): Use __builtin_clz.
(ctz32_1bit): Delete.
(ctz32): Use __builtin_ctz.
(CLZ64_MASK32): Delete.
(CLZ64_MASK16): Delete.
(CLZ64_MASK8): Delete.
(CLZ64_MASK4): Delete.
(CLZ64_MASK2): Delete.
(CLZ64_MASK1): Delete.
(clz64_nz): Use __builtin_clzl.
(ctz64_1bit): Delete.
(ctz64): Use __builtin_ctzl.
---
libgcc/config/libbid/bid_binarydecimal.c | 51 ++----------------------
1 file changed, 4 insertions(+), 47 deletions(-)
@@ -26,65 +26,22 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// Counting leading zeros in an unsigned 32-bit word
// The "_nz" version will return the wrong answer (31) for zero inputs
-#define CLZ32_MASK16 0xFFFF0000ul
-#define CLZ32_MASK8 0xFF00FF00ul
-#define CLZ32_MASK4 0xF0F0F0F0ul
-#define CLZ32_MASK2 0xCCCCCCCCul
-#define CLZ32_MASK1 0xAAAAAAAAul
-
-#define clz32_nz(n) \
- (((((n) & CLZ32_MASK16) <= ((n) & ~CLZ32_MASK16)) ? 16 : 0) + \
- ((((n) & CLZ32_MASK8) <= ((n) & ~CLZ32_MASK8)) ? 8 : 0) + \
- ((((n) & CLZ32_MASK4) <= ((n) & ~CLZ32_MASK4)) ? 4 : 0) + \
- ((((n) & CLZ32_MASK2) <= ((n) & ~CLZ32_MASK2)) ? 2 : 0) + \
- ((((n) & CLZ32_MASK1) <= ((n) & ~CLZ32_MASK1)) ? 1 : 0))
-
+#define clz32_nz(n) (__builtin_clz (n))
#define clz32(n) (((n)==0) ? 32 : clz32_nz(n))
// Counting trailing zeros in an unsigned 32-bit word
-// The ctz32_1bit version is for a single bit
-
-#define ctz32_1bit(n) \
- ((((n) & ~CLZ32_MASK16) ? 0 : 16) + \
- (((n) & ~CLZ32_MASK8) ? 0 : 8) + \
- (((n) & ~CLZ32_MASK4) ? 0 : 4) + \
- (((n) & ~CLZ32_MASK2) ? 0 : 2) + \
- (((n) & ~CLZ32_MASK1) ? 0 : 1))
+#define ctz32(n) (__builtin_ctz (n))
-#define ctz32(n) (((n) == 0) ? 32 : ctz32_1bit((n) & -(n)))
// Counting leading zeros in an unsigned 64-bit word
// The "_nz" version will return the wrong answer (63) for zero inputs
-#define CLZ64_MASK32 0xFFFFFFFF00000000ull
-#define CLZ64_MASK16 0xFFFF0000FFFF0000ull
-#define CLZ64_MASK8 0xFF00FF00FF00FF00ull
-#define CLZ64_MASK4 0xF0F0F0F0F0F0F0F0ull
-#define CLZ64_MASK2 0xCCCCCCCCCCCCCCCCull
-#define CLZ64_MASK1 0xAAAAAAAAAAAAAAAAull
-
-#define clz64_nz(n) \
- (((((n) & CLZ64_MASK32) <= ((n) & ~CLZ64_MASK32)) ? 32 : 0) + \
- ((((n) & CLZ64_MASK16) <= ((n) & ~CLZ64_MASK16)) ? 16 : 0) + \
- ((((n) & CLZ64_MASK8) <= ((n) & ~CLZ64_MASK8)) ? 8 : 0) + \
- ((((n) & CLZ64_MASK4) <= ((n) & ~CLZ64_MASK4)) ? 4 : 0) + \
- ((((n) & CLZ64_MASK2) <= ((n) & ~CLZ64_MASK2)) ? 2 : 0) + \
- ((((n) & CLZ64_MASK1) <= ((n) & ~CLZ64_MASK1)) ? 1 : 0)) \
-
+#define clz64_nz(n) ( (__SIZEOF_LONG__ == 8) ?__builtin_clzl(n) : __builtin_clzll(n) )
#define clz64(n) (((n)==0) ? 64 : clz64_nz(n))
// Counting trailing zeros in an unsigned 64-bit word
-// The ctz64_1bit version is for a single bit
-
-#define ctz64_1bit(n) \
- ((((n) & ~CLZ64_MASK32) ? 0 : 32) + \
- (((n) & ~CLZ64_MASK16) ? 0 : 16) + \
- (((n) & ~CLZ64_MASK8) ? 0 : 8) + \
- (((n) & ~CLZ64_MASK4) ? 0 : 4) + \
- (((n) & ~CLZ64_MASK2) ? 0 : 2) + \
- (((n) & ~CLZ64_MASK1) ? 0 : 1))
+#define ctz64(n) ( (__SIZEOF_LONG__ == 8) ?__builtin_ctzl(n) : __builtin_ctzll(n) )
-#define ctz64(n) (((n) == 0) ? 64 : ctz64_1bit((n) & -(n)))
// Counting leading zeros in an unsigned 2-part 128-bit word