[llvm-commits] CVS: llvm/include/llvm/Support/MathExtras.h
Chris Lattner
lattner at cs.uiuc.edu
Tue Aug 2 12:15:41 PDT 2005
Changes in directory llvm/include/llvm/Support:
MathExtras.h updated: 1.16 -> 1.17
---
Log message:
Consolidate all of the various log2 computing functions into MathExtras.h.
Also, provide accelerated implementations when building with GCC.
Patch contributed by Jim Laskey!
---
Diffs of the changes: (+135 -22)
MathExtras.h | 157 ++++++++++++++++++++++++++++++++++++++++++++++++++---------
1 files changed, 135 insertions(+), 22 deletions(-)
Index: llvm/include/llvm/Support/MathExtras.h
diff -u llvm/include/llvm/Support/MathExtras.h:1.16 llvm/include/llvm/Support/MathExtras.h:1.17
--- llvm/include/llvm/Support/MathExtras.h:1.16 Thu Apr 21 15:44:59 2005
+++ llvm/include/llvm/Support/MathExtras.h Tue Aug 2 14:15:30 2005
@@ -18,32 +18,145 @@
namespace llvm {
-#if defined(log2)
-# undef log2
+// NOTE: The following support functions use the _32/_64 extensions instead of type
+// overloading so that signed and unsigned integers can be used without ambiguity.
+
+
+// Hi_32 - This function returns the high 32 bits of a 64 bit value.
+inline unsigned Hi_32(uint64_t Value) {
+ return (unsigned)(Value >> 32);
+}
+
+// Lo_32 - This function returns the low 32 bits of a 64 bit value.
+inline unsigned Lo_32(uint64_t Value) {
+ return (unsigned)Value;
+}
+
+// is?Type - these functions produce optimal testing for integer data types.
+inline bool isInt8 (int Value) { return ( signed char )Value == Value; }
+inline bool isUInt8 (int Value) { return (unsigned char )Value == Value; }
+inline bool isInt16 (int Value) { return ( signed short)Value == Value; }
+inline bool isUInt16(int Value) { return (unsigned short)Value == Value; }
+inline bool isInt32 (int64_t Value) { return ( signed int )Value == Value; }
+inline bool isUInt32(int64_t Value) { return (unsigned int )Value == Value; }
+
+// isMask_32 - This function returns true if the argument is a sequence of ones starting
+// at the least significant bit with the remainder zero (32 bit version.)
+// Ex. isMask_32(0x0000FFFFU) == true.
+inline const bool isMask_32(unsigned Value) {
+ return Value && ((Value + 1) & Value) == 0;
+}
+
+// isMask_64 - This function returns true if the argument is a sequence of ones starting
+// at the least significant bit with the remainder zero (64 bit version.)
+inline const bool isMask_64(uint64_t Value) {
+ return Value && ((Value + 1) & Value) == 0;
+}
+
+// isShiftedMask_32 - This function returns true if the argument contains a sequence of ones
+// with the remainder zero (32 bit version.)
+// Ex. isShiftedMask_32(0x0000FF00U) == true.
+inline const bool isShiftedMask_32(unsigned Value) {
+ return isMask_32((Value - 1) | Value);
+}
+
+// isShiftedMask_64 - This function returns true if the argument contains a sequence of ones
+// with the remainder zero (64 bit version.)
+inline const bool isShiftedMask_64(uint64_t Value) {
+ return isMask_64((Value - 1) | Value);
+}
+
+// isPowerOf2_32 - This function returns true if the argument is a power of two > 0.
+// Ex. isPowerOf2_32(0x00100000U) == true (32 bit edition.)
+inline bool isPowerOf2_32(unsigned Value) {
+ return Value && !(Value & (Value - 1));
+}
+
+// isPowerOf2_64 - This function returns true if the argument is a power of two > 0
+// (64 bit edition.)
+inline bool isPowerOf2_64(uint64_t Value) {
+ return Value && !(Value & (Value - 1LL));
+}
+
+// CountLeadingZeros_32 - this function performs the platform optimal form
+// of counting the number of zeros from the most significant bit to the first one bit.
+// Ex. CountLeadingZeros_32(0x00F000FF) == 8.
+// Returns 32 if the word is zero.
+inline unsigned CountLeadingZeros_32(unsigned Value) {
+ unsigned Count; // result
+ #if __GNUC__ >= 4
+ // PowerPC is defined for __builtin_clz(0)
+ #if defined(__ppc__) || defined(__ppc64__)
+ if (!Value) return 32;
#endif
+ Count = __builtin_clz(Value);
+ #else
+ if (!Value) return 32;
+ Count = 0;
+ // bisecton method for count leading zeros
+ for (unsigned Shift = 32 >> 1; Shift; Shift >>= 1) {
+ unsigned Tmp = Value >> Shift;
+ if (Tmp) {
+ Count |= Shift;
+ Value = Tmp;
+ }
+ }
+ #endif
+ return Count;
+}
+
+// CountLeadingZeros_64 - This function performs the platform optimal form
+// of counting the number of zeros from the most significant bit to the first one bit
+// (64 bit edition.)
+// Returns 64 if the word is zero.
+inline unsigned CountLeadingZeros_64(uint64_t Value) {
+ unsigned Count; // result
+ #if __GNUC__ >= 4
+ // PowerPC is defined for __builtin_clzll(0)
+ #if defined(__ppc__) || defined(__ppc64__)
+ if (!Value) return 64;
+ #endif
+ Count = __builtin_clzll(Value);
+ #elif sizeof(long) == sizeof(int64_t)
+ if (!Value) return 64;
+ Count = 0;
+ // bisecton method for count leading zeros
+ for (uint64_t Shift = 64 >> 1; Shift; Shift >>= 1) {
+ uint64_t Tmp = Value >> Shift;
+ if (Tmp) {
+ Count |= Shift;
+ Value = Tmp;
+ }
+}
+ #else
+ // get hi portion
+ unsigned Hi = Hi_32(Value);
+
+ // if some bits in hi portion
+ if (Hi) {
+ // leading zeros in hi portion plus all bits in lo portion
+ Count = CountLeadingZeros_32(Hi) + 32;
+ } else {
+ // get lo portion
+ unsigned Lo = Lo_32(Value);
+ // same as 32 bit value
+ Count = CountLeadingZeros_32(Lo);
+ }
+ #endif
+ return Count;
+}
-inline unsigned log2(uint64_t C) {
- unsigned getPow;
- for (getPow = 0; C > 1; ++getPow)
- C >>= 1;
- return getPow;
-}
-
-inline unsigned log2(unsigned C) {
- unsigned getPow;
- for (getPow = 0; C > 1; ++getPow)
- C >>= 1;
- return getPow;
-}
-
-inline bool isPowerOf2(int64_t C, unsigned &getPow) {
- if (C < 0) C = -C;
- if (C > 0 && C == (C & ~(C - 1))) {
- getPow = log2(static_cast<uint64_t>(C));
- return true;
+// Log2_32 - This function returns the floor log base 2 of the specified value, -1 if the value is zero.
+// (32 bit edition.)
+// Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1
+inline unsigned Log2_32(unsigned Value) {
+ return 31 - CountLeadingZeros_32(Value);
}
- return false;
+// Log2_64 - This function returns the floor log base 2 of the specified value, -1 if the value is zero.
+// (64 bit edition.)
+inline unsigned Log2_64(unsigned Value) {
+ return 63 - CountLeadingZeros_64(Value);
}
// Platform-independent wrappers for the C99 isnan() function.
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