liblzma: Avoid extern lzma_crc32_clmul() and lzma_crc64_clmul().

A CLMUL-only build will have the crcxx_clmul() inlined into
lzma_crcxx(). Previously a jump to the extern lzma_crcxx_clmul()
was needed. Notes about shared liblzma on ELF platforms:

  - On platforms that support ifunc and -fvisibility=hidden, this
    was silly because CLMUL-only build would have that single extra
    jump instruction of extra overhead.

  - On platforms that support neither -fvisibility=hidden nor linker
    version script (liblzma*.map), jumping to lzma_crcxx_clmul()
    would go via PLT so a few more instructions of overhead (still
    not a big issue but silly nevertheless).

There was a downside with static liblzma too: if an application only
needs lzma_crc64(), static linking would make the linker include the
CLMUL code for both CRC32 and CRC64 from crc_x86_clmul.o even though
the CRC32 code wouldn't be needed, thus increasing code size of the
executable (assuming that -ffunction-sections isn't used).

Also, now compilers are likely to inline crc_simd_body()
even if they don't support the always_inline attribute
(or MSVC's __forceinline). Quite possibly all compilers
that build the code do support such an attribute. But now
it likely isn't a problem even if the attribute wasn't supported.

Now all x86-specific stuff is in crc_x86_clmul.h. If other archs
The other archs can then have their own headers with their own
is_clmul_supported() and crcxx_clmul().

Another bonus is that the build system doesn't need to care if
crc_clmul.c is needed.

is_clmul_supported() stays as inline function as it's not needed
when doing a CLMUL-only build (avoids a warning about unused function).

5 files changed, 89 insertions, 85 deletions

diff --git a/src/liblzma/check/Makefile.inc b/src/liblzma/check/Makefile.inc
index 6186e10a..acff40c3 100644
--- a/src/liblzma/check/Makefile.inc
+++ b/src/liblzma/check/Makefile.inc
@@ -14,7 +14,8 @@ EXTRA_DIST += \
 liblzma_la_SOURCES += \
 	check/check.c \
 	check/check.h \
-	check/crc_common.h
+	check/crc_common.h \
+	check/crc_x86_clmul.h
 
 if COND_SMALL
 liblzma_la_SOURCES += check/crc32_small.c
@@ -27,9 +28,6 @@ if COND_ASM_X86
 liblzma_la_SOURCES += check/crc32_x86.S
 else
 liblzma_la_SOURCES += check/crc32_fast.c
-if COND_CRC_CLMUL
-liblzma_la_SOURCES += check/crc_clmul.c
-endif
 endif
 endif
 
diff --git a/src/liblzma/check/crc32_fast.c b/src/liblzma/check/crc32_fast.c
index 9fce94d3..6982836a 100644
--- a/src/liblzma/check/crc32_fast.c
+++ b/src/liblzma/check/crc32_fast.c
@@ -15,6 +15,11 @@
 #include "check.h"
 #include "crc_common.h"
 
+#ifdef CRC_CLMUL
+#	define BUILDING_CRC32_CLMUL
+#	include "crc_x86_clmul.h"
+#endif
+
 
 #ifdef CRC_GENERIC
 
@@ -132,7 +137,7 @@ typedef uint32_t (*crc32_func_type)(
 static crc32_func_type
 crc32_resolve(void)
 {
-	return is_clmul_supported() ? &lzma_crc32_clmul : &crc32_generic;
+	return is_clmul_supported() ? &crc32_clmul : &crc32_generic;
 }
 
 #if defined(HAVE_FUNC_ATTRIBUTE_IFUNC) && defined(__clang__)
@@ -221,7 +226,7 @@ lzma_crc32(const uint8_t *buf, size_t size, uint32_t crc)
 	return crc32_func(buf, size, crc);
 
 #elif defined(CRC_CLMUL)
-	return lzma_crc32_clmul(buf, size, crc);
+	return crc32_clmul(buf, size, crc);
 
 #else
 	return crc32_generic(buf, size, crc);
diff --git a/src/liblzma/check/crc64_fast.c b/src/liblzma/check/crc64_fast.c
index ce74901c..46b5c646 100644
--- a/src/liblzma/check/crc64_fast.c
+++ b/src/liblzma/check/crc64_fast.c
@@ -14,6 +14,11 @@
 #include "check.h"
 #include "crc_common.h"
 
+#ifdef CRC_CLMUL
+#	define BUILDING_CRC64_CLMUL
+#	include "crc_x86_clmul.h"
+#endif
+
 
 #ifdef CRC_GENERIC
 
@@ -97,7 +102,7 @@ typedef uint64_t (*crc64_func_type)(
 static crc64_func_type
 crc64_resolve(void)
 {
-	return is_clmul_supported() ? &lzma_crc64_clmul : &crc64_generic;
+	return is_clmul_supported() ? &crc64_clmul : &crc64_generic;
 }
 
 #if defined(HAVE_FUNC_ATTRIBUTE_IFUNC) && defined(__clang__)
@@ -160,7 +165,7 @@ lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
 	//
 	// FIXME: Lookup table isn't currently omitted on 32-bit x86,
 	// see crc64_table.c.
-	return lzma_crc64_clmul(buf, size, crc);
+	return crc64_clmul(buf, size, crc);
 
 #else
 	return crc64_generic(buf, size, crc);
diff --git a/src/liblzma/check/crc_common.h b/src/liblzma/check/crc_common.h
index c949f793..552219fe 100644
--- a/src/liblzma/check/crc_common.h
+++ b/src/liblzma/check/crc_common.h
@@ -108,70 +108,6 @@
 #		define CRC_USE_GENERIC_FOR_SMALL_INPUTS 1
 #	endif
 */
-
-#	if defined(_MSC_VER)
-#		include <intrin.h>
-#	elif defined(HAVE_CPUID_H)
-#		include <cpuid.h>
-#	endif
-
-// is_clmul_supported() must be inlined in this header file because the
-// ifunc resolver function may not support calling a function in another
-// translation unit. Depending on compiler-toolchain and flags, a call to
-// a function defined in another translation unit could result in a
-// reference to the PLT, which is unsafe to do in an ifunc resolver. The
-// ifunc resolver runs very early when loading a shared library, so the PLT
-// entries may not be setup at that time. Inlining this function duplicates
-// the function body in crc32_resolve() and crc64_resolve(), but this is
-// acceptable because the function results in very few instructions.
-static inline bool
-is_clmul_supported(void)
-{
-	int success = 1;
-	uint32_t r[4]; // eax, ebx, ecx, edx
-
-#if defined(_MSC_VER)
-	// This needs <intrin.h> with MSVC. ICC has it as a built-in
-	// on all platforms.
-	__cpuid(r, 1);
-#elif defined(HAVE_CPUID_H)
-	// Compared to just using __asm__ to run CPUID, this also checks
-	// that CPUID is supported and saves and restores ebx as that is
-	// needed with GCC < 5 with position-independent code (PIC).
-	success = __get_cpuid(1, &r[0], &r[1], &r[2], &r[3]);
-#else
-	// Just a fallback that shouldn't be needed.
-	__asm__("cpuid\n\t"
-			: "=a"(r[0]), "=b"(r[1]), "=c"(r[2]), "=d"(r[3])
-			: "a"(1), "c"(0));
 #endif
 
-	// Returns true if these are supported:
-	// CLMUL (bit 1 in ecx)
-	// SSSE3 (bit 9 in ecx)
-	// SSE4.1 (bit 19 in ecx)
-	const uint32_t ecx_mask = (1 << 1) | (1 << 9) | (1 << 19);
-	return success && (r[2] & ecx_mask) == ecx_mask;
-
-	// Alternative methods that weren't used:
-	//   - ICC's _may_i_use_cpu_feature: the other methods should work too.
-	//   - GCC >= 6 / Clang / ICX __builtin_cpu_supports("pclmul")
-	//
-	// CPUID decding is needed with MSVC anyway and older GCC. This keeps
-	// the feature checks in the build system simpler too. The nice thing
-	// about __builtin_cpu_supports would be that it generates very short
-	// code as is it only reads a variable set at startup but a few bytes
-	// doesn't matter here.
-}
-
-#endif
-
-/// CRC32 implemented with the x86 CLMUL instruction.
-extern uint32_t lzma_crc32_clmul(const uint8_t *buf, size_t size,
-		uint32_t crc);
-
-/// CRC64 implemented with the x86 CLMUL instruction.
-extern uint64_t lzma_crc64_clmul(const uint8_t *buf, size_t size,
-		uint64_t crc);
-
 #endif
diff --git a/src/liblzma/check/crc_clmul.c b/src/liblzma/check/crc_x86_clmul.h
index 381948a9..7a47204a 100644
--- a/src/liblzma/check/crc_clmul.c
+++ b/src/liblzma/check/crc_x86_clmul.h
@@ -1,11 +1,10 @@
 ///////////////////////////////////////////////////////////////////////////////
 //
-/// \file       crc_clmul.c
+/// \file       crc_x86_clmul.h
 /// \brief      CRC32 and CRC64 implementations using CLMUL instructions.
 ///
-/// lzma_crc32_clmul() and lzma_crc64_clmul() use 32/64-bit x86
-/// SSSE3, SSE4.1, and CLMUL instructions. This is compatible with
-/// Elbrus 2000 (E2K) too.
+/// crc32_clmul() and crc64_clmul() use 32/64-bit x86 SSSE3, SSE4.1, and
+/// CLMUL instructions. This is compatible with Elbrus 2000 (E2K) too.
 ///
 /// They were derived from
 /// https://www.researchgate.net/publication/263424619_Fast_CRC_computation
@@ -27,9 +26,20 @@
 //
 ///////////////////////////////////////////////////////////////////////////////
 
-#include "crc_common.h"
+// This file must not be included more than once.
+#ifdef LZMA_CRC_X86_CLMUL_H
+#	error crc_x86_clmul.h was included twice.
+#endif
+#define LZMA_CRC_X86_CLMUL_H
+
 #include <immintrin.h>
 
+#if defined(_MSC_VER)
+#	include <intrin.h>
+#elif defined(HAVE_CPUID_H)
+#	include <cpuid.h>
+#endif
+
 
 // EDG-based compilers (Intel's classic compiler and compiler for E2K) can
 // define __GNUC__ but the attribute must not be used with them.
@@ -225,12 +235,12 @@ calc_hi(uint64_t p, uint64_t a, int n)
 }
 */
 
-#ifdef HAVE_CHECK_CRC32
+#ifdef BUILDING_CRC32_CLMUL
 
 crc_attr_target
 crc_attr_no_sanitize_address
-extern uint32_t
-lzma_crc32_clmul(const uint8_t *buf, size_t size, uint32_t crc)
+static uint32_t
+crc32_clmul(const uint8_t *buf, size_t size, uint32_t crc)
 {
 #ifndef CRC_USE_GENERIC_FOR_SMALL_INPUTS
 	// The code assumes that there is at least one byte of input.
@@ -265,7 +275,7 @@ lzma_crc32_clmul(const uint8_t *buf, size_t size, uint32_t crc)
 	v0 = _mm_xor_si128(v0, v2);   // [2]
 	return ~(uint32_t)_mm_extract_epi32(v0, 2);
 }
-#endif // HAVE_CHECK_CRC32
+#endif // BUILDING_CRC32_CLMUL
 
 
 /////////////////////
@@ -299,7 +309,7 @@ calc_hi(uint64_t poly, uint64_t a)
 }
 */
 
-#ifdef HAVE_CHECK_CRC64
+#ifdef BUILDING_CRC64_CLMUL
 
 // MSVC (VS2015 - VS2022) produces bad 32-bit x86 code from the CLMUL CRC
 // code when optimizations are enabled (release build). According to the bug
@@ -318,8 +328,8 @@ calc_hi(uint64_t poly, uint64_t a)
 
 crc_attr_target
 crc_attr_no_sanitize_address
-extern uint64_t
-lzma_crc64_clmul(const uint8_t *buf, size_t size, uint64_t crc)
+static uint64_t
+crc64_clmul(const uint8_t *buf, size_t size, uint64_t crc)
 {
 #ifndef CRC_USE_GENERIC_FOR_SMALL_INPUTS
 	// The code assumes that there is at least one byte of input.
@@ -366,4 +376,54 @@ lzma_crc64_clmul(const uint8_t *buf, size_t size, uint64_t crc)
 #	pragma optimize("", on)
 #endif
 
-#endif // HAVE_CHECK_CRC64
+#endif // BUILDING_CRC64_CLMUL
+
+
+// is_clmul_supported() must be inlined in this header file because the
+// ifunc resolver function may not support calling a function in another
+// translation unit. Depending on compiler-toolchain and flags, a call to
+// a function defined in another translation unit could result in a
+// reference to the PLT, which is unsafe to do in an ifunc resolver. The
+// ifunc resolver runs very early when loading a shared library, so the PLT
+// entries may not be setup at that time. Inlining this function duplicates
+// the function body in crc32_resolve() and crc64_resolve(), but this is
+// acceptable because the function results in very few instructions.
+static inline bool
+is_clmul_supported(void)
+{
+	int success = 1;
+	uint32_t r[4]; // eax, ebx, ecx, edx
+
+#if defined(_MSC_VER)
+	// This needs <intrin.h> with MSVC. ICC has it as a built-in
+	// on all platforms.
+	__cpuid(r, 1);
+#elif defined(HAVE_CPUID_H)
+	// Compared to just using __asm__ to run CPUID, this also checks
+	// that CPUID is supported and saves and restores ebx as that is
+	// needed with GCC < 5 with position-independent code (PIC).
+	success = __get_cpuid(1, &r[0], &r[1], &r[2], &r[3]);
+#else
+	// Just a fallback that shouldn't be needed.
+	__asm__("cpuid\n\t"
+			: "=a"(r[0]), "=b"(r[1]), "=c"(r[2]), "=d"(r[3])
+			: "a"(1), "c"(0));
+#endif
+
+	// Returns true if these are supported:
+	// CLMUL (bit 1 in ecx)
+	// SSSE3 (bit 9 in ecx)
+	// SSE4.1 (bit 19 in ecx)
+	const uint32_t ecx_mask = (1 << 1) | (1 << 9) | (1 << 19);
+	return success && (r[2] & ecx_mask) == ecx_mask;
+
+	// Alternative methods that weren't used:
+	//   - ICC's _may_i_use_cpu_feature: the other methods should work too.
+	//   - GCC >= 6 / Clang / ICX __builtin_cpu_supports("pclmul")
+	//
+	// CPUID decding is needed with MSVC anyway and older GCC. This keeps
+	// the feature checks in the build system simpler too. The nice thing
+	// about __builtin_cpu_supports would be that it generates very short
+	// code as is it only reads a variable set at startup but a few bytes
+	// doesn't matter here.
+}