Decode UTF-8 with PEXT when BMI2 is available

2 files changed, 86 insertions, 17 deletions

diff --git a/make.c b/make.c
index c7ad047..79a1760 100644
--- a/make.c
+++ b/make.c
@@ -21,9 +21,10 @@
 #endif
 
 enum {
-	SIMD_AVX2 = 1 << 0,
-	SIMD_NEON = 1 << 1,
-	SIMD_SSE4_1 = 1 << 2,
+	CPU_AVX2   = 1 << 0,
+	CPU_NEON   = 1 << 1,
+	CPU_SSE4_1 = 1 << 2,
+	CPU_BMI2   = 1 << 3,
 };
 
 static char *cflags_all[] = {
@@ -60,7 +61,7 @@ static char *cflags_rls[] = {
 
 static char *argv0;
 static bool fflag, Fflag, rflag, Sflag;
-static int simd_flags;
+static int cpu_flags;
 
 static void ld(void);
 static void mkgmp(int);
@@ -213,8 +214,10 @@ cc(void *arg)
 		strspushenv(&cmd, "CFLAGS", cflags_dbg, lengthof(cflags_dbg));
 	if (!rflag && !Sflag)
 		strspushl(&cmd, "-fsanitize=address,undefined");
-	if (simd_flags != 0)
+	if (cpu_flags != 0)
 		strspushl(&cmd, "-DORYX_SIMD=1");
+	if (cpu_flags & CPU_BMI2)
+		strspushl(&cmd, "-DORYX_BMI2=1");
 	llvmquery(&cmd, LLVM_CFLAGS);
 	strspushl(&cmd, "-o", dst, "-c", src);
 
@@ -261,8 +264,10 @@ cc_test(void *arg)
 		strspushenv(&cmd, "CFLAGS", cflags_dbg, lengthof(cflags_dbg));
 	if (!rflag && !Sflag)
 		strspushl(&cmd, "-fsanitize=address,undefined");
-	if (simd_flags != 0)
+	if (cpu_flags != 0)
 		strspushl(&cmd, "-DORYX_SIMD=1");
+	if (cpu_flags & CPU_BMI2)
+		strspushl(&cmd, "-DORYX_BMI2=1");
 	strspushl(&cmd, "-Isrc", "-o", dst, src);
 	strspush(&cmd, d.objs, d.len);
 
@@ -382,9 +387,9 @@ tagvalid(const char *file)
 		char *tag;
 		int flag;
 	} tags[] = {
-		{"avx2",    SIMD_AVX2  },
-		{"sse4_1",  SIMD_SSE4_1},
-		{"neon",    SIMD_NEON  },
+		{"avx2",    CPU_AVX2  },
+		{"sse4_1",  CPU_SSE4_1},
+		{"neon",    CPU_NEON  },
 		{"generic", 0          },
 	};
 
@@ -399,7 +404,7 @@ tagvalid(const char *file)
 		sprintf(buf, "%.*s-%s%s", (int)(sep - file), file, tags[i].tag, ext);
 
 		if (fexists(buf)
-		    && ((simd_flags & tags[i].flag) != 0 || tags[i].flag == 0))
+		    && ((cpu_flags & tags[i].flag) != 0 || tags[i].flag == 0))
 		{
 			want_and_have = buf;
 			break;
@@ -425,27 +430,36 @@ chk_cpu_flags(void)
 	if (!rflag)
 		return;
 
+	/* Test for BMI2 */
+#if __BMI2__
+	cpu_flags |= CPU_BMI2;
+#elif __GNUC__ && __x86_64__
+	asm volatile("cpuid" : "=b"(exx) : "a"(7), "c"(0));
+	if (exx & (1 << 8))
+		cpu_flags |= CPU_BMI2;
+#endif
+
 	/* Test for AVX512 */
 #if __AVX512F__
-	simd_flags |= SIMD_AVX2;
+	cpu_flags |= CPU_AVX2;
 #elif __GNUC__ && __x86_64__
 	asm volatile("cpuid" : "=b"(exx) : "a"(7), "c"(0));
 	if (exx & (1 << 5))
-		simd_flags |= SIMD_AVX2;
+		cpu_flags |= CPU_AVX2;
 #endif
 
 	/* Test for SSE4.1 */
 #if __SSE4_1__
-	simd_flags |= SIMD_SSE4_1;
+	cpu_flags |= CPU_SSE4_1;
 #elif __GNUC__ && __x86_64__
 	asm volatile("cpuid" : "=c"(exx) : "a"(1), "c"(0));
 	if (exx & (1 << 19))
-		simd_flags |= SIMD_SSE4_1;
+		cpu_flags |= CPU_SSE4_1;
 #endif
 
 	/* Test for NEON */
 #if __ARM_NEON || __ARM_NEON__
-	simd_flags |= SIMD_NEON;
+	cpu_flags |= CPU_NEON;
 #endif
 }
 
diff --git a/src/unicode.c b/src/unicode.c
index b32b413..6ad34a3 100644
--- a/src/unicode.c
+++ b/src/unicode.c
@@ -1,3 +1,7 @@
+#if ORYX_BMI2
+#	include <immintrin.h>
+#endif
+
 #include "common.h"
 #include "types.h"
 #include "unicode-data.h"
@@ -45,9 +49,19 @@ RUNE_IS_GEN(rune_is_xidc, xidc_stage1, xidc_stage2, 128)
 static const char lengths[] = {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
                                0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 3, 3, 4, 0};
 static const rune mins[] = {RUNE_C(4194304), 0, 128, 2048, RUNE_C(65536)};
+static const int shifte[] = {0, 6, 4, 2, 0};
+
+#if ORYX_BMI2
+static const uint32_t pextmsk[] = {
+	0x7F000000,
+	0x1F3F0000,
+	0x0F3F3F00,
+	0x073F3F3F,
+};
+#else
 static const int masks[] = {0x00, 0x7f, 0x1f, 0x0f, 0x07};
 static const int shiftc[] = {0, 18, 12, 6, 0};
-static const int shifte[] = {0, 6, 4, 2, 0};
+#endif
 
 rune
 utf8_decode(const uchar **buf)
@@ -55,12 +69,32 @@ utf8_decode(const uchar **buf)
 	const uchar *s = *buf;
 	int len = lengths[s[0] >> 3];
 	*buf = s + len + !len;
-
+#if ORYX_BMI2
+	rune c = 0;
+	switch (len) {
+	case 4:
+		c |= (rune)s[3] <<  0;
+		/* fallthrough */
+	case 3:
+		c |= (rune)s[2] <<  8;
+		/* fallthrough */
+	case 2:
+		c |= (rune)s[1] << 16;
+		/* fallthrough */
+	case 1:
+		c |= (rune)s[0] << 24;
+		break;
+	default:
+		__builtin_unreachable();
+	}
+	return _pext_u32(c, pextmsk[len - 1]);
+#else
 	rune c = (rune)(s[0] & masks[len]) << 18;
 	c |= (rune)(s[1] & 0x3f) << 12;
 	c |= (rune)(s[2] & 0x3f) << 6;
 	c |= (rune)(s[3] & 0x3f) << 0;
 	return c >> shiftc[len];
+#endif
 }
 
 size_t
@@ -72,11 +106,32 @@ utf8_validate_off(const uchar *s, size_t len)
 
 		const uchar *next = s + len + !len;
 
+#if ORYX_BMI2
+		rune c = 0;
+		switch (len) {
+		case 4:
+			c |= (rune)s[3] <<  0;
+			/* fallthrough */
+		case 3:
+			c |= (rune)s[2] <<  8;
+			/* fallthrough */
+		case 2:
+			c |= (rune)s[1] << 16;
+			/* fallthrough */
+		case 1:
+			c |= (rune)s[0] << 24;
+			break;
+		default:
+			__builtin_unreachable();
+		}
+		c = _pext_u32(c, pextmsk[len - 1]);
+#else
 		rune c = (rune)(s[0] & masks[len]) << 18;
 		c |= (rune)(s[1] & 0x3f) << 12;
 		c |= (rune)(s[2] & 0x3f) << 6;
 		c |= (rune)(s[3] & 0x3f) << 0;
 		c >>= shiftc[len];
+#endif
 
 		int e = (c < mins[len]) << 6;
 		e |= ((c >> 11) == 0x1B) << 7;