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Diffstat (limited to 'compiler-rt/lib/builtins/ctzsi2.c')
-rw-r--r--compiler-rt/lib/builtins/ctzsi2.c69
1 files changed, 34 insertions, 35 deletions
diff --git a/compiler-rt/lib/builtins/ctzsi2.c b/compiler-rt/lib/builtins/ctzsi2.c
index d5dfe256893..405b2f771cd 100644
--- a/compiler-rt/lib/builtins/ctzsi2.c
+++ b/compiler-rt/lib/builtins/ctzsi2.c
@@ -17,40 +17,39 @@
/* Precondition: a != 0 */
-COMPILER_RT_ABI si_int
-__ctzsi2(si_int a)
-{
- su_int x = (su_int)a;
- si_int t = ((x & 0x0000FFFF) == 0) << 4; /* if (x has no small bits) t = 16 else 0 */
- x >>= t; /* x = [0 - 0xFFFF] + higher garbage bits */
- su_int r = t; /* r = [0, 16] */
- /* return r + ctz(x) */
- t = ((x & 0x00FF) == 0) << 3;
- x >>= t; /* x = [0 - 0xFF] + higher garbage bits */
- r += t; /* r = [0, 8, 16, 24] */
- /* return r + ctz(x) */
- t = ((x & 0x0F) == 0) << 2;
- x >>= t; /* x = [0 - 0xF] + higher garbage bits */
- r += t; /* r = [0, 4, 8, 12, 16, 20, 24, 28] */
- /* return r + ctz(x) */
- t = ((x & 0x3) == 0) << 1;
- x >>= t;
- x &= 3; /* x = [0 - 3] */
- r += t; /* r = [0 - 30] and is even */
- /* return r + ctz(x) */
+COMPILER_RT_ABI si_int __ctzsi2(si_int a) {
+ su_int x = (su_int)a;
+ si_int t = ((x & 0x0000FFFF) == 0)
+ << 4; /* if (x has no small bits) t = 16 else 0 */
+ x >>= t; /* x = [0 - 0xFFFF] + higher garbage bits */
+ su_int r = t; /* r = [0, 16] */
+ /* return r + ctz(x) */
+ t = ((x & 0x00FF) == 0) << 3;
+ x >>= t; /* x = [0 - 0xFF] + higher garbage bits */
+ r += t; /* r = [0, 8, 16, 24] */
+ /* return r + ctz(x) */
+ t = ((x & 0x0F) == 0) << 2;
+ x >>= t; /* x = [0 - 0xF] + higher garbage bits */
+ r += t; /* r = [0, 4, 8, 12, 16, 20, 24, 28] */
+ /* return r + ctz(x) */
+ t = ((x & 0x3) == 0) << 1;
+ x >>= t;
+ x &= 3; /* x = [0 - 3] */
+ r += t; /* r = [0 - 30] and is even */
+ /* return r + ctz(x) */
-/* The branch-less return statement below is equivalent
- * to the following switch statement:
- * switch (x)
- * {
- * case 0:
- * return r + 2;
- * case 2:
- * return r + 1;
- * case 1:
- * case 3:
- * return r;
- * }
- */
- return r + ((2 - (x >> 1)) & -((x & 1) == 0));
+ /* The branch-less return statement below is equivalent
+ * to the following switch statement:
+ * switch (x)
+ * {
+ * case 0:
+ * return r + 2;
+ * case 2:
+ * return r + 1;
+ * case 1:
+ * case 3:
+ * return r;
+ * }
+ */
+ return r + ((2 - (x >> 1)) & -((x & 1) == 0));
}
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