Changes in directory llvm/lib/Support:
APInt.cpp updated: 1.60 -> 1.61
---
Log message:
Use a real table in sqrt to shorten and quicken the code.
Thanks for the idea Chris.
---
Diffs of the changes: (+10 -14)
APInt.cpp | 24 ++++++++++--------------
1 files changed, 10 insertions(+), 14 deletions(-)
Index: llvm/lib/Support/APInt.cpp
diff -u llvm/lib/Support/APInt.cpp:1.60 llvm/lib/Support/APInt.cpp:1.61
--- llvm/lib/Support/APInt.cpp:1.60 Wed Feb 28 23:39:56 2007
+++ llvm/lib/Support/APInt.cpp Thu Mar 1 00:23:32 2007
@@ -1174,20 +1174,16 @@
// Use a fast table for some small values. This also gets rid of some
// rounding errors in libc sqrt for small values.
if (magnitude <= 5) {
- uint64_t result = 0;
- switch (isSingleWord() ? VAL : pVal[0]) {
- case 0 : break;
- case 1 : case 2 : result = 1; break;
- case 3 : case 4 : case 5: case 6: result = 2; break;
- case 7 : case 8 : case 9: case 10: case 11: case 12:
- result = 3; break;
- case 13: case 14: case 15: case 16: case 17: case 18: case 19: case 20:
- result = 4; break;
- case 21: case 22: case 23: case 24: case 25: case 26: case 27: case 28:
- case 29: case 30: result = 5; break;
- case 31: result = 6; break;
- }
- return APInt(BitWidth, result);
+ static uint8_t results[32] = {
+ /* 0 */ 0,
+ /* 1- 2 */ 1, 1,
+ /* 3- 6 */ 2, 2, 2, 2,
+ /* 7-12 */ 3, 3, 3, 3, 3, 3,
+ /* 13-20 */ 4, 4, 4, 4, 4, 4, 4, 4,
+ /* 21-30 */ 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
+ /* 31 */ 6
+ };
+ return APInt(BitWidth, results[ (isSingleWord() ? VAL : pVal[0]) ]);
}
// If the magnitude of the value fits in less than 52 bits (the precision of
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