src: add a macro to create a FMV resolver

kloetzl · Dec 27, 2023 · 3b783c9 · 3b783c9
1 parent ee1dc17
commit 3b783c9
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Showing 6 changed files with 123 additions and 286 deletions.
diff --git a/src/dna4_count_mismatches_rc_x86.c b/src/dna4_count_mismatches_rc_x86.c
@@ -1,6 +1,6 @@
 /**
  * SPDX-License-Identifier: MIT
- * Copyright 2021 - 2022 (C) Fabian Klötzl
+ * Copyright 2021 - 2023 (C) Fabian Klötzl
  */
 
 #include "config.h"
@@ -27,61 +27,12 @@ dna4_count_mismatches_rc_select(void)
 	}
 }
 
-#if CAN_IFUNC && __has_attribute(ifunc)
-
-DNA_PUBLIC
-size_t
-dna4_count_mismatches_rc(const char *begin, const char *end, const char *other)
-	__attribute__((ifunc("dna4_count_mismatches_rc_select")));
-
-#elif defined(__APPLE__) && 0
-
-void *
-dna4_count_mismatches_rc_macho(void) __asm__("_dna4_count_mismatches_rc");
-
-DNA_PUBLIC
-void *
-dna4_count_mismatches_rc_macho(void)
-{
-	__asm__(".symbol_resolver _dna4_count_mismatches_rc");
-	return (void *)dna4_count_mismatches_rc_select();
-}
-
-#else
-
-// If ifunc is unavailable (for instance on macOS or hurd) we have to implement
-// the functionality ourselves. Using a function pointer is faster than a
-// boolean variable.
-
-size_t
-dna4_count_mismatches_rc_callonce(
-	const char *begin, const char *end, const char *other);
-
-static dna4_count_mismatches_rc_fn *dna4_count_mismatches_rc_fnptr =
-	dna4_count_mismatches_rc_callonce;
-
-DNA_LOCAL
-size_t
-dna4_count_mismatches_rc_callonce(
-	const char *begin, const char *end, const char *other)
-{
-	dna4_count_mismatches_rc_fnptr = dna4_count_mismatches_rc_select();
-	return dna4_count_mismatches_rc_fnptr(begin, end, other);
-}
-
-DNA_PUBLIC
-size_t
-dna4_count_mismatches_rc(const char *begin, const char *end, const char *other)
-{
-	return dna4_count_mismatches_rc_fnptr(begin, end, other);
-}
-
-DNA_LOCAL
-DNA_CONSTRUCTOR
-void
-dna4_count_mismatches_rc_init(void)
-{
-	dna4_count_mismatches_rc_fnptr = dna4_count_mismatches_rc_select();
-}
-
-#endif
+RESOLVER(
+	size_t,
+	dna4_count_mismatches_rc,
+	const char *,
+	begin,
+	const char *,
+	end,
+	const char *,
+	other)
diff --git a/src/dna4_fill_random_x86.c b/src/dna4_fill_random_x86.c
@@ -1,6 +1,6 @@
 /**
  * SPDX-License-Identifier: MIT
- * Copyright 2022 (C) Fabian Klötzl
+ * Copyright 2022 - 2023 (C) Fabian Klötzl
  */
 
 #include "config.h"
@@ -27,58 +27,4 @@ dna4_fill_random_select(void)
 	}
 }
 
-#if CAN_IFUNC && __has_attribute(ifunc)
-
-DNA_PUBLIC
-void
-dna4_fill_random(char *dest, char *end, uint32_t seed)
-	__attribute__((ifunc("dna4_fill_random_select")));
-
-#elif defined(__APPLE__) && 0
-
-void *
-dna4_fill_random_macho(void) __asm__("_dna4_fill_random");
-
-DNA_PUBLIC
-void *
-dna4_fill_random_macho(void)
-{
-	__asm__(".symbol_resolver _dna4_fill_random");
-	return (void *)dna4_fill_random_select();
-}
-
-#else
-
-// If ifunc is unavailable (for instance on macOS or hurd) we have to implement
-// the functionality ourselves. Using a function pointer is faster than a
-// boolean variable.
-
-void
-dna4_fill_random_callonce(char *dest, char *end, uint32_t seed);
-
-static dna4_fill_random_fn *dna4_fill_random_fnptr = dna4_fill_random_callonce;
-
-DNA_LOCAL
-void
-dna4_fill_random_callonce(char *dest, char *end, uint32_t seed)
-{
-	dna4_fill_random_fnptr = dna4_fill_random_select();
-	dna4_fill_random_fnptr(dest, end, seed);
-}
-
-DNA_PUBLIC
-void
-dna4_fill_random(char *dest, char *end, uint32_t seed)
-{
-	dna4_fill_random_fnptr(dest, end, seed);
-}
-
-DNA_LOCAL
-DNA_CONSTRUCTOR
-void
-dna4_fill_random_init(void)
-{
-	dna4_fill_random_fnptr = dna4_fill_random_select();
-}
-
-#endif
+RESOLVER_VOID(void, dna4_fill_random, char *, dest, char *, end, uint32_t, seed)
diff --git a/src/dna4_revcomp_x86.c b/src/dna4_revcomp_x86.c
@@ -1,6 +1,6 @@
 /**
  * SPDX-License-Identifier: MIT
- * Copyright 2018 - 2022 (C) Fabian Klötzl
+ * Copyright 2018 - 2023 (C) Fabian Klötzl
  */
 
 #include "config.h"
@@ -27,58 +27,5 @@ dna4_revcomp_select(void)
 	}
 }
 
-#if CAN_IFUNC && __has_attribute(ifunc)
-
-DNA_PUBLIC
-char *
-dna4_revcomp(const char *begin, const char *end, char *dest)
-	__attribute__((ifunc("dna4_revcomp_select")));
-
-#elif defined(__APPLE__) && 0
-
-void *
-dna4_revcomp_macho(void) __asm__("_dna4_revcomp");
-
-DNA_PUBLIC
-void *
-dna4_revcomp_macho(void)
-{
-	__asm__(".symbol_resolver _dna4_revcomp");
-	return (void *)dna4_revcomp_select();
-}
-
-#else
-
-// If ifunc is unavailable (for instance on macOS or hurd) we have to implement
-// the functionality ourselves. Using a function pointer is faster than a
-// boolean variable.
-
-char *
-dna4_revcomp_callonce(const char *begin, const char *end, char *dest);
-
-static dna4_revcomp_fn *dna4_revcomp_fnptr = dna4_revcomp_callonce;
-
-DNA_LOCAL
-char *
-dna4_revcomp_callonce(const char *begin, const char *end, char *dest)
-{
-	dna4_revcomp_fnptr = dna4_revcomp_select();
-	return dna4_revcomp_fnptr(begin, end, dest);
-}
-
-DNA_PUBLIC
-char *
-dna4_revcomp(const char *begin, const char *end, char *dest)
-{
-	return dna4_revcomp_fnptr(begin, end, dest);
-}
-
-DNA_LOCAL
-DNA_CONSTRUCTOR
-void
-dna4_revcomp_init(void)
-{
-	dna4_revcomp_fnptr = dna4_revcomp_select();
-}
-
-#endif
+RESOLVER(
+	char *, dna4_revcomp, const char *, begin, const char *, end, char *, dest)
diff --git a/src/dna_internal.h b/src/dna_internal.h
@@ -81,6 +81,95 @@ dna4_fill_random_fn dna4_fill_random_avx2;
 dna4_fill_random_fn dna4_fill_random_sse42;
 dna4_fill_random_fn dna4_fill_random_generic;
 
+// Macros that help with defining a runtime resolver for function multi
+// versioning.
+
+#define STRINGIFY(s) #s
+#define GET_1(_1, ...) _1
+#define GET_2(_1, _2, ...) _2
+#define GET_3(_1, _2, _3, ...) _3
+#define GET_4(_1, _2, _3, _4, ...) _4
+#define GET_5(_1, _2, _3, _4, _5, ...) _5
+#define GET_6(_1, _2, _3, _4, _5, _6) _6
+
+#define ARG_1_TYPE(...) GET_1(__VA_ARGS__)
+#define ARG_1_NAME(...) GET_2(__VA_ARGS__)
+#define ARG_2_TYPE(...) GET_3(__VA_ARGS__)
+#define ARG_2_NAME(...) GET_4(__VA_ARGS__)
+#define ARG_3_TYPE(...) GET_5(__VA_ARGS__)
+#define ARG_3_NAME(...) GET_6(__VA_ARGS__)
+
+#define ARG_1(...) ARG_1_TYPE(__VA_ARGS__) ARG_1_NAME(__VA_ARGS__)
+#define ARG_2(...) ARG_2_TYPE(__VA_ARGS__) ARG_2_NAME(__VA_ARGS__)
+#define ARG_3(...) ARG_3_TYPE(__VA_ARGS__) ARG_3_NAME(__VA_ARGS__)
+
+#if CAN_IFUNC && __has_attribute(ifunc)
+
+// On Linux there is the special "ifunc" syntax we can use to pick the optimal
+// implementation at runtime.
+
+#define RESOLVER(RETTYPE, NAME, ...)                                           \
+	DNA_PUBLIC                                                                 \
+	void NAME(ARG_1(__VA_ARGS__), ARG_2(__VA_ARGS__), ARG_3(__VA_ARGS__))      \
+		__attribute__((ifunc(STRINGIFY(NAME) "_select")));
+
+#define RESOLVER_VOID(RETTYPE, NAME, ...)                                      \
+	RESOLVER(RETTYPE, NAME, __VA_ARGS__)
+
+#else
+
+// If ifunc is unavailable (for instance on macOS or hurd) we have to implement
+// the functionality ourselves. To this end we define a function pointer that
+// points to the optimal implementation. Said pointer is initiallised to a
+// "XXX_callonce" function which, when called, picks the best implementation,
+// sets the pointer, and finally forwards the arguments to the actual function.
+// This overhead on the first function call can be avoided if the system
+// supports __attribute__((constructor)). Then the optimal implementation will
+// be picked when the program is first loaded.
+
+#define RESOLVER_META(STATEMENT, RETTYPE, NAME, ...)                           \
+                                                                               \
+	RETTYPE NAME##_callonce(                                                   \
+		ARG_1(__VA_ARGS__), ARG_2(__VA_ARGS__), ARG_3(__VA_ARGS__));           \
+                                                                               \
+	static NAME##_fn *NAME##_fnptr = NAME##_callonce;                          \
+                                                                               \
+	DNA_LOCAL                                                                  \
+	RETTYPE NAME##_callonce(                                                   \
+		ARG_1(__VA_ARGS__), ARG_2(__VA_ARGS__), ARG_3(__VA_ARGS__))            \
+	{                                                                          \
+		NAME##_fnptr = NAME##_select();                                        \
+		STATEMENT NAME##_fnptr(                                                \
+			ARG_1_NAME(__VA_ARGS__), ARG_2_NAME(__VA_ARGS__),                  \
+			ARG_3_NAME(__VA_ARGS__));                                          \
+	}                                                                          \
+                                                                               \
+	DNA_PUBLIC                                                                 \
+	RETTYPE NAME(ARG_1(__VA_ARGS__), ARG_2(__VA_ARGS__), ARG_3(__VA_ARGS__))   \
+	{                                                                          \
+		STATEMENT NAME##_fnptr(                                                \
+			ARG_1_NAME(__VA_ARGS__), ARG_2_NAME(__VA_ARGS__),                  \
+			ARG_3_NAME(__VA_ARGS__));                                          \
+	}                                                                          \
+                                                                               \
+	DNA_LOCAL                                                                  \
+	DNA_CONSTRUCTOR                                                            \
+	void NAME##_init(void)                                                     \
+	{                                                                          \
+		NAME##_fnptr = NAME##_select();                                        \
+	}
+
+// In C it isn't allowed to have a return statement with a void expression in a
+// void function. Thus, we need an extra overload that removes the return
+// statement from the above code. In C++ this wouldn't be a problem.
+
+#define RESOLVER_VOID(RETTYPE, NAME, ...)                                      \
+	RESOLVER_META((void), RETTYPE, NAME, __VA_ARGS__)
+#define RESOLVER(RETTYPE, NAME, ...)                                           \
+	RESOLVER_META(return, RETTYPE, NAME, __VA_ARGS__)
+
+#endif
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/dnax_count_mismatches_x86.c b/src/dnax_count_mismatches_x86.c
@@ -30,61 +30,12 @@ dnax_count_mismatches_select(void)
 	}
 }
 
-#if CAN_IFUNC && __has_attribute(ifunc)
-
-DNA_PUBLIC
-size_t
-dnax_count_mismatches(const char *begin, const char *end, const char *other)
-	__attribute__((ifunc("dnax_count_mismatches_select")));
-
-#elif defined(__APPLE__) && 0
-
-void *
-dnax_count_mismatches_macho(void) __asm__("_dnax_count_mismatches");
-
-DNA_PUBLIC
-void *
-dnax_count_mismatches_macho(void)
-{
-	__asm__(".symbol_resolver _dnax_count_mismatches");
-	return (void *)dnax_count_mismatches_select();
-}
-
-#else
-
-// If ifunc is unavailable (for instance on macOS or hurd) we have to implement
-// the functionality ourselves. Using a function pointer is faster than a
-// boolean variable.
-
-size_t
-dnax_count_mismatches_callonce(
-	const char *begin, const char *end, const char *other);
-
-static dnax_count_mismatches_fn *dnax_count_mismatches_fnptr =
-	dnax_count_mismatches_callonce;
-
-DNA_LOCAL
-size_t
-dnax_count_mismatches_callonce(
-	const char *begin, const char *end, const char *other)
-{
-	dnax_count_mismatches_fnptr = dnax_count_mismatches_select();
-	return dnax_count_mismatches_fnptr(begin, end, other);
-}
-
-DNA_PUBLIC
-size_t
-dnax_count_mismatches(const char *begin, const char *end, const char *other)
-{
-	return dnax_count_mismatches_fnptr(begin, end, other);
-}
-
-DNA_LOCAL
-DNA_CONSTRUCTOR
-void
-dnax_count_mismatches_init(void)
-{
-	dnax_count_mismatches_fnptr = dnax_count_mismatches_select();
-}
-
-#endif
+RESOLVER(
+	size_t,
+	dnax_count_mismatches,
+	const char *,
+	begin,
+	const char *,
+	end,
+	const char *,
+	other)