Adding upstream version 14.5.upstream/14.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 64 insertions, 0 deletions

diff --git a/src/port/pg_crc32c_sse42_choose.c b/src/port/pg_crc32c_sse42_choose.c
new file mode 100644
index 0000000..0608e02
--- /dev/null
+++ b/src/port/pg_crc32c_sse42_choose.c
@@ -0,0 +1,64 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_crc32c_sse42_choose.c
+ *	  Choose between Intel SSE 4.2 and software CRC-32C implementation.
+ *
+ * On first call, checks if the CPU we're running on supports Intel SSE
+ * 4.2. If it does, use the special SSE instructions for CRC-32C
+ * computation. Otherwise, fall back to the pure software implementation
+ * (slicing-by-8).
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/port/pg_crc32c_sse42_choose.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "c.h"
+
+#ifdef HAVE__GET_CPUID
+#include <cpuid.h>
+#endif
+
+#ifdef HAVE__CPUID
+#include <intrin.h>
+#endif
+
+#include "port/pg_crc32c.h"
+
+static bool
+pg_crc32c_sse42_available(void)
+{
+	unsigned int exx[4] = {0, 0, 0, 0};
+
+#if defined(HAVE__GET_CPUID)
+	__get_cpuid(1, &exx[0], &exx[1], &exx[2], &exx[3]);
+#elif defined(HAVE__CPUID)
+	__cpuid(exx, 1);
+#else
+#error cpuid instruction not available
+#endif
+
+	return (exx[2] & (1 << 20)) != 0;	/* SSE 4.2 */
+}
+
+/*
+ * This gets called on the first call. It replaces the function pointer
+ * so that subsequent calls are routed directly to the chosen implementation.
+ */
+static pg_crc32c
+pg_comp_crc32c_choose(pg_crc32c crc, const void *data, size_t len)
+{
+	if (pg_crc32c_sse42_available())
+		pg_comp_crc32c = pg_comp_crc32c_sse42;
+	else
+		pg_comp_crc32c = pg_comp_crc32c_sb8;
+
+	return pg_comp_crc32c(crc, data, len);
+}
+
+pg_crc32c	(*pg_comp_crc32c) (pg_crc32c crc, const void *data, size_t len) = pg_comp_crc32c_choose;