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count-leading-zeros: Fix a link error on 32-bit MSVC and a test failure
From: |
Bruno Haible |
Subject: |
count-leading-zeros: Fix a link error on 32-bit MSVC and a test failure |
Date: |
Mon, 05 Sep 2022 01:36:24 +0200 |
On 32-bit MSVC, I see a compilation error:
/home/bruno/msvc/compile cl -nologo -MD -L/usr/local/msvc32/lib -o
test-count-leading-zeros.exe test-count-leading-zeros.obj libtests.a
../gllib/libgnu.a libtests.a ../gllib/libgnu.a libtests.a
test-count-leading-zeros.obj : error LNK2019: unresolved external symbol
__BitScanReverse64 referenced in function _count_leading_zeros_ll
test-count-leading-zeros.exe : fatal error LNK1120: 1 unresolved externals
make[4]: *** [Makefile:16525: test-count-leading-zeros.exe] Error 2
Additionally, on 64-bit MSVC, the test-count-leading-zeros.exe test fails.
This patch fixes both issues.
2022-09-04 Bruno Haible <bruno@clisp.org>
count-leading-zeros: Fix a link error on 32-bit MSVC and a test failure.
* lib/count-leading-zeros.h: Correct syntax for #pragma intrinsic.
(COUNT_LEADING_ZEROS): Fix the return value.
(count_leading_zeros_ll): Use two _BitScanReverse invocations instead
of a _BitScanReverse64 invocation.
diff --git a/lib/count-leading-zeros.h b/lib/count-leading-zeros.h
index 354641af0a..4b4f5d4f9a 100644
--- a/lib/count-leading-zeros.h
+++ b/lib/count-leading-zeros.h
@@ -43,13 +43,17 @@ extern "C" {
# define COUNT_LEADING_ZEROS(BUILTIN, MSC_BUILTIN, TYPE) \
return x ? BUILTIN (x) : CHAR_BIT * sizeof x;
#elif _MSC_VER
-# pragma intrinsic _BitScanReverse
-# pragma intrinsic _BitScanReverse64
+# pragma intrinsic (_BitScanReverse)
+# if defined _M_X64
+# pragma intrinsic (_BitScanReverse64)
+# endif
# define COUNT_LEADING_ZEROS(BUILTIN, MSC_BUILTIN, TYPE) \
do \
{ \
unsigned long result; \
- return MSC_BUILTIN (&result, x) ? result : CHAR_BIT * sizeof x; \
+ if (MSC_BUILTIN (&result, x)) \
+ return CHAR_BIT * sizeof x - 1 - result; \
+ return CHAR_BIT * sizeof x; \
} \
while (0)
#else
@@ -109,8 +113,18 @@ count_leading_zeros_l (unsigned long int x)
COUNT_LEADING_ZEROS_INLINE int
count_leading_zeros_ll (unsigned long long int x)
{
+#if (defined _MSC_VER && !defined __clang__) && !defined _M_X64
+ /* 32-bit MSVC does not have _BitScanReverse64, only _BitScanReverse. */
+ unsigned long result;
+ if (_BitScanReverse (&result, (unsigned long) (x >> 32)))
+ return CHAR_BIT * sizeof x - 1 - 32 - result;
+ if (_BitScanReverse (&result, (unsigned long) x))
+ return CHAR_BIT * sizeof x - 1 - result;
+ return CHAR_BIT * sizeof x;
+#else
COUNT_LEADING_ZEROS (__builtin_clzll, _BitScanReverse64,
unsigned long long int);
+#endif
}
#ifdef __cplusplus
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