Define GNU clz builtins equivalents for MSVC

[angelsl]

Put the functions in int_lib.h instead, since some of the functions that use them only include that

[compnerd]

Why is it insufficient to do this?

#if defined(_MSC_VER) && !defined(__clang__)
#define __builtin_clz __builtin_clzl
#define __builtin_ctz __builtin_ctzl
#define __builtin_clzl __builtin_ctzll
#endif

I don't understand the definition of __builtin_clzll. _BitScanReverse64 it is implemented in terms of __builtin_clzll for clang.

lib/builtins/int_lib.h

82

This should be:

#if defined(_MSC_VER) && !defined(__clang__)

[angelsl]

_BitScanReverse gives the index of the first set bit starting from the most significant bit, where the index is zero from the LSB.

[angelsl]

Corrections made.

[compnerd]

lib/builtins/int_lib.h

101

You should be able to drop the braces; use 2-space indents as per the LLVM style.

[angelsl]

Corrections made.

[compnerd]

SVN r249515.

lib/builtins/int_lib.h

 COMPILER_RT_ABI tu_int __udivmodti4(tu_int a, tu_int b, tu_int* rem);
 #endif
 
+/* Definitions for builtins unavailable on MSVC */
+#if defined(_MSC_VER) && !defined(__clang__)
+#include <intrin.h>
+
+uint32_t __inline __builtin_ctz(uint32_t value) {
+  uint32_t trailing_zero = 0;
+  if (_BitScanForward(&trailing_zero, value))
+    return trailing_zero;
+  else
+    return 32;
+}
+
+uint32_t __inline __builtin_clz(uint32_t value) {
+  uint32_t leading_zero = 0;
+  if (_BitScanReverse(&leading_zero, value))
+    return 31 - leading_zero;
+  else
+    return 32;
+}
+
+uint32_t __inline __builtin_clzll(uint64_t value) {
+  uint32_t leading_zero = 0;
+  if (_BitScanReverse64(&leading_zero, value))
+    return 63 - leading_zero;
+  else
+    return 64;
+}
+
+#define __builtin_clzl __builtin_clzll
+#endif
+
 #endif /* INT_LIB_H */