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Simplify rotate implementation a bit..

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Much more understandable/readable as a result, and probably more efficient.

Patch by: Aaron Watry

llvm-svn: 184997
This commit is contained in:
Tom Stellard 2013-06-26 18:21:18 +00:00
parent 0bb381eaec
commit 8c1e72f46a
2 changed files with 37 additions and 21 deletions
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16
libclc/generic/include/clc/integer/gentype.inc
View File

@ -2,7 +2,9 @@
#define GENTYPE char
#define UGENTYPE uchar
#define SGENTYPE char
#define SCALAR 1
#include BODY
#undef SCALAR
#undef GENTYPE
#undef UGENTYPE
#undef SGENTYPE
@ -50,7 +52,9 @@
#define GENTYPE uchar
#define UGENTYPE uchar
#define SGENTYPE char
#define SCALAR 1
#include BODY
#undef SCALAR
#undef GENTYPE
#undef UGENTYPE
#undef SGENTYPE
@ -101,7 +105,9 @@
#define GENTYPE short
#define UGENTYPE ushort
#define SGENTYPE short
#define SCALAR 1
#include BODY
#undef SCALAR
#undef GENTYPE
#undef UGENTYPE
#undef SGENTYPE
@ -149,7 +155,9 @@
#define GENTYPE ushort
#define UGENTYPE ushort
#define SGENTYPE short
#define SCALAR 1
#include BODY
#undef SCALAR
#undef GENTYPE
#undef UGENTYPE
#undef SGENTYPE
@ -200,7 +208,9 @@
#define GENTYPE int
#define UGENTYPE uint
#define SGENTYPE int
#define SCALAR 1
#include BODY
#undef SCALAR
#undef GENTYPE
#undef UGENTYPE
#undef SGENTYPE
@ -248,7 +258,9 @@
#define GENTYPE uint
#define UGENTYPE uint
#define SGENTYPE int
#define SCALAR 1
#include BODY
#undef SCALAR
#undef GENTYPE
#undef UGENTYPE
#undef SGENTYPE
@ -299,7 +311,9 @@
#define GENTYPE long
#define UGENTYPE ulong
#define SGENTYPE long
#define SCALAR 1
#include BODY
#undef SCALAR
#undef GENTYPE
#undef UGENTYPE
#undef SGENTYPE
@ -347,7 +361,9 @@
#define GENTYPE ulong
#define UGENTYPE ulong
#define SGENTYPE long
#define SCALAR 1
#include BODY
#undef SCALAR
#undef GENTYPE
#undef UGENTYPE
#undef SGENTYPE

42
libclc/generic/lib/integer/rotate.inc
View File

@ -11,25 +11,25 @@ _CLC_OVERLOAD _CLC_DEF GENTYPE rotate(GENTYPE x, GENTYPE n){
//Try to avoid extra work if someone's spinning the value through multiple
//full rotations
n = n % (GENTYPE)GENSIZE;
//Determine if we're doing a right or left shift on each component
//The actual shift algorithm is based on a rotate right
//e.g. a rotate of int by 5 bits becomes rotate right by 26 bits
// and a rotate of int by -4 bits becomes rotate right by 4
GENTYPE amt = (n > (GENTYPE)0 ? (GENTYPE)GENSIZE - n : (GENTYPE)0 - n );
//Calculate the bits that will wrap
GENTYPE mask = ( (GENTYPE)1 << amt ) - (GENTYPE)1;
GENTYPE wrapped_bits = x & mask;
//Shift the input value right and then AND a mask that eliminates
//sign-extension interference
//if the rotate amount is 0, just use ~0 for a mask
GENTYPE se_mask = !amt ? ~((GENTYPE)0) :
( ( (GENTYPE)1 << ((GENTYPE)GENSIZE - amt) ) - (GENTYPE)1 );
GENTYPE unwrapped_bits = x >> amt;
unwrapped_bits &= se_mask;
//Finally shift the input right after moving the wrapped bits into position
return unwrapped_bits | (wrapped_bits << ( (GENTYPE)GENSIZE - amt ) );
#ifdef SCALAR
if (n > 0){
return (x << n) | (((UGENTYPE)x) >> (GENSIZE - n));
} else if (n == 0){
return x;
} else {
return ( (((UGENTYPE)x) >> -n) | (x << (GENSIZE + n)) );
}
#else
UGENTYPE x_1 = __builtin_astype(x, UGENTYPE);
UGENTYPE amt;
amt = (n < (GENTYPE)0 ? __builtin_astype((GENTYPE)0-n, UGENTYPE) : (UGENTYPE)0);
x_1 = (x_1 >> amt) | (x_1 << ((UGENTYPE)GENSIZE - amt));
amt = (n < (GENTYPE)0 ? (UGENTYPE)0 : __builtin_astype(n, UGENTYPE));
x_1 = (x_1 << amt) | (x_1 >> ((UGENTYPE)GENSIZE - amt));
return __builtin_astype(x_1, GENTYPE);
#endif
}