Avoid explicit checks for _BitScanForward[64]

3 files changed, 10 insertions, 29 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4793afe5..4d0bb217 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -433,20 +433,6 @@ IF(HAVE_INTRIN_H)
             __cpuid(regs, 0);
             return regs[0];
         }" HAVE_CPUID_INTRINSIC)
-    CHECK_C_SOURCE_COMPILES("#include <intrin.h>
-        int main()
-        {
-            unsigned long idx = 0;
-            _BitScanForward64(&idx, 1);
-            return idx;
-        }" HAVE_BITSCANFORWARD64_INTRINSIC)
-    CHECK_C_SOURCE_COMPILES("#include <intrin.h>
-        int main()
-        {
-            unsigned long idx = 0;
-            _BitScanForward(&idx, 1);
-            return idx;
-        }" HAVE_BITSCANFORWARD_INTRINSIC)
 ENDIF()
 
 check_cxx_source_compiles("#include <cstdlib>
diff --git a/common/alnumeric.h b/common/alnumeric.h
index 9158b764..df05b966 100644
--- a/common/alnumeric.h
+++ b/common/alnumeric.h
@@ -132,7 +132,7 @@ inline int fallback_popcnt64(uint64_t v)
 }
 #define POPCNT64 fallback_popcnt64
 
-#if defined(HAVE_BITSCANFORWARD64_INTRINSIC)
+#if defined(_WIN64)
 
 inline int msvc64_ctz32(uint32_t v)
 {
@@ -149,7 +149,7 @@ inline int msvc64_ctz64(uint64_t v)
 }
 #define CTZ64 msvc64_ctz64
 
-#elif defined(HAVE_BITSCANFORWARD_INTRINSIC)
+#elif defined(_WIN32)
 
 inline int msvc_ctz32(uint32_t v)
 {
@@ -225,8 +225,9 @@ inline int float2int(float f) noexcept
 #if defined(HAVE_SSE_INTRINSICS)
     return _mm_cvtt_ss2si(_mm_set_ss(f));
 
-#elif ((defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) && \
-       !defined(__SSE_MATH__)) || (defined(_MSC_VER) && defined(_M_IX86_FP) && _M_IX86_FP == 0)
+#elif (defined(_MSC_VER) && defined(_M_IX86_FP) && _M_IX86_FP == 0) \
+    || ((defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) \
+        &&  !defined(__SSE_MATH__))
     int sign, shift, mant;
     union {
         float f;
@@ -260,9 +261,9 @@ inline int double2int(double d) noexcept
 #if defined(HAVE_SSE_INTRINSICS)
     return _mm_cvttsd_si32(_mm_set_sd(d));
 
-#elif ((defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) && \
-       !defined(__SSE2_MATH__)) || (defined(_MSC_VER) && defined(_M_IX86_FP) && _M_IX86_FP < 2)
-
+#elif (defined(_MSC_VER) && defined(_M_IX86_FP) && _M_IX86_FP < 2) \
+    || ((defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) \
+        &&  !defined(__SSE2_MATH__))
     int sign, shift;
     int64_t mant;
     union {
@@ -296,8 +297,8 @@ inline int double2int(double d) noexcept
  */
 inline float fast_roundf(float f) noexcept
 {
-#if (defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) && \
-    !defined(__SSE_MATH__)
+#if (defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) \
+    && !defined(__SSE_MATH__)
 
     float out;
     __asm__ __volatile__("frndint" : "=t"(out) : "0"(f));
diff --git a/config.h.in b/config.h.in
index 75aacc0d..2de3640e 100644
--- a/config.h.in
+++ b/config.h.in
@@ -107,12 +107,6 @@
 /* Define if we have the __cpuid() intrinsic */
 #cmakedefine HAVE_CPUID_INTRINSIC
 
-/* Define if we have the _BitScanForward64() intrinsic */
-#cmakedefine HAVE_BITSCANFORWARD64_INTRINSIC
-
-/* Define if we have the _BitScanForward() intrinsic */
-#cmakedefine HAVE_BITSCANFORWARD_INTRINSIC
-
 /* Define if we have SSE intrinsics */
 #cmakedefine HAVE_SSE_INTRINSICS