pg_strtoint_fastpath4.patch

diff --git a/src/backend/utils/adt/numutils.c b/src/backend/utils/adt/numutils.c
index 471fbb7ee6..7067bc5d48 100644
--- a/src/backend/utils/adt/numutils.c
+++ b/src/backend/utils/adt/numutils.c
@@ -122,9 +122,84 @@ pg_strtoint16_safe(const char *s, Node *escontext)
 	const char *firstdigit;
 	uint16		tmp = 0;
 	bool		neg = false;
+	unsigned char digit;
+
+	/*
+	 * The majority of cases are likely to be base-10 digits without any
+	 * underscore separator characters.  We'll first try to parse the string with
+	 * the assumption that's the case and only fallback on a slower
+	 * implementation which handles hex, octal and binary strings and
+	 * underscores if the fastpath version cannot parse the string.
+	 */
+
+	/* leave it up to the slow path to look for leading spaces */
+
+	if (*ptr == '-')
+	{
+		ptr++;
+		neg = true;
+	}
+
+	/* a leading '+' is uncommon so leave that for the slow path */
+
+	/* process the first digit */
+	digit = (*ptr - '0');
+
+	/*
+	 * Exploit unsigned arithmetic to save having to check both the upper and
+	 * lower bounds of the digit.
+	 */
+	if (likely(digit < 10))
+	{
+		ptr++;
+		tmp = digit;
+	}
+	else
+	{
+		/* we need at least one digit */
+		goto slow;
+	}
+
+	/* process remaining digits */
+	for (;;)
+	{
+		digit = (*ptr - '0');
+
+		if (digit >= 10)
+			break;
+
+		ptr++;
+
+		if (unlikely(tmp > -(PG_INT16_MIN / 10)))
+			goto out_of_range;
+
+		tmp = tmp * 10 + digit;
+	}
+
+	/* when the string does not end in a digit, let the slow path handle it */
+	if (unlikely(*ptr != '\0'))
+		goto slow;
+
+	if (neg)
+	{
+		/* check the negative equivalent will fit without overflowing */
+		if (unlikely(tmp > (uint16) (-(PG_INT16_MIN + 1)) + 1))
+			goto out_of_range;
+		return -((int16) tmp);
+	}
+
+	if (unlikely(tmp > PG_INT16_MAX))
+		goto out_of_range;
+
+	return (int16) tmp;
+
+slow:
+	tmp = 0;
+	ptr = s;
+	/* no need to reset neg */
 
 	/* skip leading spaces */
-	while (likely(*ptr) && isspace((unsigned char) *ptr))
+	while (isspace((unsigned char) *ptr))
 		ptr++;
 
 	/* handle sign */
@@ -141,7 +216,7 @@ pg_strtoint16_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		for (;;)
 		{
 			if (isxdigit((unsigned char) *ptr))
 			{
@@ -165,7 +240,7 @@ pg_strtoint16_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		for (;;)
 		{
 			if (*ptr >= '0' && *ptr <= '7')
 			{
@@ -189,7 +264,7 @@ pg_strtoint16_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		for (;;)
 		{
 			if (*ptr >= '0' && *ptr <= '1')
 			{
@@ -213,9 +288,9 @@ pg_strtoint16_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr;
 
-		while (*ptr)
+		for (;;)
 		{
-			if (isdigit((unsigned char) *ptr))
+			if (*ptr >= '0' && *ptr <= '9')
 			{
 				if (unlikely(tmp > -(PG_INT16_MIN / 10)))
 					goto out_of_range;
@@ -242,7 +317,7 @@ pg_strtoint16_safe(const char *s, Node *escontext)
 		goto invalid_syntax;
 
 	/* allow trailing whitespace, but not other trailing chars */
-	while (*ptr != '\0' && isspace((unsigned char) *ptr))
+	while (isspace((unsigned char) *ptr))
 		ptr++;
 
 	if (unlikely(*ptr != '\0'))
@@ -300,9 +375,84 @@ pg_strtoint32_safe(const char *s, Node *escontext)
 	const char *firstdigit;
 	uint32		tmp = 0;
 	bool		neg = false;
+	unsigned char digit;
+
+	/*
+	 * The majority of cases are likely to be base-10 digits without any
+	 * underscore separator characters.  We'll first try to parse the string with
+	 * the assumption that's the case and only fallback on a slower
+	 * implementation which handles hex, octal and binary strings and
+	 * underscores if the fastpath version cannot parse the string.
+	 */
+
+	/* leave it up to the slow path to look for leading spaces */
+
+	if (*ptr == '-')
+	{
+		ptr++;
+		neg = true;
+	}
+
+	/* a leading '+' is uncommon so leave that for the slow path */
+
+	/* process the first digit */
+	digit = (*ptr - '0');
+
+	/*
+	 * Exploit unsigned arithmetic to save having to check both the upper and
+	 * lower bounds of the digit.
+	 */
+	if (likely(digit < 10))
+	{
+		ptr++;
+		tmp = digit;
+	}
+	else
+	{
+		/* we need at least one digit */
+		goto slow;
+	}
+
+	/* process remaining digits */
+	for (;;)
+	{
+		digit = (*ptr - '0');
+
+		if (digit >= 10)
+			break;
+
+		ptr++;
+
+		if (unlikely(tmp > -(PG_INT32_MIN / 10)))
+			goto out_of_range;
+
+		tmp = tmp * 10 + digit;
+	}
+
+	/* when the string does not end in a digit, let the slow path handle it */
+	if (unlikely(*ptr != '\0'))
+		goto slow;
+
+	if (neg)
+	{
+		/* check the negative equivalent will fit without overflowing */
+		if (unlikely(tmp > (uint32) (-(PG_INT32_MIN + 1)) + 1))
+			goto out_of_range;
+		return -((int32) tmp);
+	}
+
+	if (unlikely(tmp > PG_INT32_MAX))
+		goto out_of_range;
+
+	return (int32) tmp;
+
+slow:
+	tmp = 0;
+	ptr = s;
+	/* no need to reset neg */
 
 	/* skip leading spaces */
-	while (likely(*ptr) && isspace((unsigned char) *ptr))
+	while (isspace((unsigned char) *ptr))
 		ptr++;
 
 	/* handle sign */
@@ -319,7 +469,7 @@ pg_strtoint32_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		for (;;)
 		{
 			if (isxdigit((unsigned char) *ptr))
 			{
@@ -343,7 +493,7 @@ pg_strtoint32_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		for (;;)
 		{
 			if (*ptr >= '0' && *ptr <= '7')
 			{
@@ -367,7 +517,7 @@ pg_strtoint32_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		for (;;)
 		{
 			if (*ptr >= '0' && *ptr <= '1')
 			{
@@ -391,9 +541,9 @@ pg_strtoint32_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr;
 
-		while (*ptr)
+		for (;;)
 		{
-			if (isdigit((unsigned char) *ptr))
+			if (*ptr >= '0' && *ptr <= '9')
 			{
 				if (unlikely(tmp > -(PG_INT32_MIN / 10)))
 					goto out_of_range;
@@ -420,7 +570,7 @@ pg_strtoint32_safe(const char *s, Node *escontext)
 		goto invalid_syntax;
 
 	/* allow trailing whitespace, but not other trailing chars */
-	while (*ptr != '\0' && isspace((unsigned char) *ptr))
+	while (isspace((unsigned char) *ptr))
 		ptr++;
 
 	if (unlikely(*ptr != '\0'))
@@ -478,9 +628,84 @@ pg_strtoint64_safe(const char *s, Node *escontext)
 	const char *firstdigit;
 	uint64		tmp = 0;
 	bool		neg = false;
+	unsigned char digit;
+
+	/*
+	 * The majority of cases are likely to be base-10 digits without any
+	 * underscore separator characters.  We'll first try to parse the string with
+	 * the assumption that's the case and only fallback on a slower
+	 * implementation which handles hex, octal and binary strings and
+	 * underscores if the fastpath version cannot parse the string.
+	 */
+
+	/* leave it up to the slow path to look for leading spaces */
+
+	if (*ptr == '-')
+	{
+		ptr++;
+		neg = true;
+	}
+
+	/* a leading '+' is uncommon so leave that for the slow path */
+
+	/* process the first digit */
+	digit = (*ptr - '0');
+
+	/*
+	 * Exploit unsigned arithmetic to save having to check both the upper and
+	 * lower bounds of the digit.
+	 */
+	if (likely(digit < 10))
+	{
+		ptr++;
+		tmp = digit;
+	}
+	else
+	{
+		/* we need at least one digit */
+		goto slow;
+	}
+
+	/* process remaining digits */
+	for (;;)
+	{
+		digit = (*ptr - '0');
+
+		if (digit >= 10)
+			break;
+
+		ptr++;
+
+		if (unlikely(tmp > -(PG_INT64_MIN / 10)))
+			goto out_of_range;
+
+		tmp = tmp * 10 + digit;
+	}
+
+	/* when the string does not end in a digit, let the slow path handle it */
+	if (unlikely(*ptr != '\0'))
+		goto slow;
+
+	if (neg)
+	{
+		/* check the negative equivalent will fit without overflowing */
+		if (unlikely(tmp > (uint64) (-(PG_INT64_MIN + 1)) + 1))
+			goto out_of_range;
+		return -((int64) tmp);
+	}
+
+	if (unlikely(tmp > PG_INT64_MAX))
+		goto out_of_range;
+
+	return (int64) tmp;
+
+slow:
+	tmp = 0;
+	ptr = s;
+	/* no need to reset neg */
 
 	/* skip leading spaces */
-	while (*ptr && isspace((unsigned char) *ptr))
+	while (isspace((unsigned char) *ptr))
 		ptr++;
 
 	/* handle sign */
@@ -497,7 +722,7 @@ pg_strtoint64_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		for (;;)
 		{
 			if (isxdigit((unsigned char) *ptr))
 			{
@@ -521,7 +746,7 @@ pg_strtoint64_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		for (;;)
 		{
 			if (*ptr >= '0' && *ptr <= '7')
 			{
@@ -545,7 +770,7 @@ pg_strtoint64_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		for (;;)
 		{
 			if (*ptr >= '0' && *ptr <= '1')
 			{
@@ -569,9 +794,9 @@ pg_strtoint64_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr;
 
-		while (*ptr)
+		for (;;)
 		{
-			if (isdigit((unsigned char) *ptr))
+			if (*ptr >= '0' && *ptr <= '9')
 			{
 				if (unlikely(tmp > -(PG_INT64_MIN / 10)))
 					goto out_of_range;
@@ -598,7 +823,7 @@ pg_strtoint64_safe(const char *s, Node *escontext)
 		goto invalid_syntax;
 
 	/* allow trailing whitespace, but not other trailing chars */
-	while (*ptr != '\0' && isspace((unsigned char) *ptr))
+	while (isspace((unsigned char) *ptr))
 		ptr++;
 
 	if (unlikely(*ptr != '\0'))