[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
count-trailing-zeros: Fix a link error on 32-bit MSVC
From: |
Bruno Haible |
Subject: |
count-trailing-zeros: Fix a link error on 32-bit MSVC |
Date: |
Mon, 05 Sep 2022 01:32:04 +0200 |
On 32-bit MSVC, I'm seeing this link error:
/home/bruno/msvc/compile cl -nologo -MD -L/usr/local/msvc32/lib -o
test-count-trailing-zeros.exe test-count-trailing-zeros.obj libtests.a
../gllib/libgnu.a libtests.a ../gllib/libgnu.a libtests.a
test-count-trailing-zeros.obj : error LNK2019: unresolved external symbol
__BitScanForward64 referenced in function _count_trailing_zeros_ll
test-count-trailing-zeros.exe : fatal error LNK1120: 1 unresolved externals
make[4]: *** [Makefile:16533: test-count-trailing-zeros.exe] Error 2
The reason is that, as documented in
https://docs.microsoft.com/en-us/cpp/intrinsics/bitscanforward-bitscanforward64
_BitScanForward64 does not exist in 32-bit mode.
This patch fixes it.
2022-09-04 Bruno Haible <bruno@clisp.org>
count-trailing-zeros: Fix a link error on 32-bit MSVC.
* lib/count-trailing-zeros.h: Correct syntax for #pragma intrinsic.
(count_trailing_zeros_ll): Use two _BitScanForward invocations instead
of a _BitScanForward64 invocation.
diff --git a/lib/count-trailing-zeros.h b/lib/count-trailing-zeros.h
index 9a989a4324..61fbdf2980 100644
--- a/lib/count-trailing-zeros.h
+++ b/lib/count-trailing-zeros.h
@@ -43,8 +43,10 @@ extern "C" {
# define COUNT_TRAILING_ZEROS(BUILTIN, MSC_BUILTIN, TYPE) \
return x ? BUILTIN (x) : CHAR_BIT * sizeof x;
#elif _MSC_VER
-# pragma intrinsic _BitScanForward
-# pragma intrinsic _BitScanForward64
+# pragma intrinsic (_BitScanForward)
+# if defined _M_X64
+# pragma intrinsic (_BitScanForward64)
+# endif
# define COUNT_TRAILING_ZEROS(BUILTIN, MSC_BUILTIN, TYPE) \
do \
{ \
@@ -101,8 +103,18 @@ count_trailing_zeros_l (unsigned long int x)
COUNT_TRAILING_ZEROS_INLINE int
count_trailing_zeros_ll (unsigned long long int x)
{
+#if (defined _MSC_VER && !defined __clang__) && !defined _M_X64
+ /* 32-bit MSVC does not have _BitScanForward64, only _BitScanForward. */
+ unsigned long result;
+ if (_BitScanForward (&result, (unsigned long) x))
+ return result;
+ if (_BitScanForward (&result, (unsigned long) (x >> 32)))
+ return result + 32;
+ return CHAR_BIT * sizeof x;
+#else
COUNT_TRAILING_ZEROS (__builtin_ctzll, _BitScanForward64,
unsigned long long int);
+#endif
}
#ifdef __cplusplus
[Prev in Thread] |
Current Thread |
[Next in Thread] |
- count-trailing-zeros: Fix a link error on 32-bit MSVC,
Bruno Haible <=