[APInt] Cleanup the reverseBits slow case a little.
Use lshrInPlace. Use single bit extract and operator|=(uint64_t) to avoid a few temporary APInts.
llvm-svn: 300527
diff --git a/llvm/lib/Support/APInt.cpp b/llvm/lib/Support/APInt.cpp
index 1094a61..5ac98e1 100644
--- a/llvm/lib/Support/APInt.cpp
+++ b/llvm/lib/Support/APInt.cpp
@@ -774,14 +774,12 @@
}
APInt Val(*this);
- APInt Reversed(*this);
- int S = BitWidth - 1;
+ APInt Reversed(BitWidth, 0);
+ unsigned S = BitWidth;
- const APInt One(BitWidth, 1);
-
- for ((Val = Val.lshr(1)); Val != 0; (Val = Val.lshr(1))) {
+ for (; Val != 0; Val.lshrInPlace(1)) {
Reversed <<= 1;
- Reversed |= (Val & One);
+ Reversed |= Val[0];
--S;
}