diff --git a/src/backend/utils/adt/numutils.c b/src/backend/utils/adt/numutils.c
index 471fbb7ee6..12d8b7eb69 100644
--- a/src/backend/utils/adt/numutils.c
+++ b/src/backend/utils/adt/numutils.c
@@ -124,7 +124,7 @@ pg_strtoint16_safe(const char *s, Node *escontext)
 	bool		neg = false;
 
 	/* skip leading spaces */
-	while (likely(*ptr) && isspace((unsigned char) *ptr))
+	while (isspace((unsigned char) *ptr))
 		ptr++;
 
 	/* handle sign */
@@ -141,14 +141,17 @@ pg_strtoint16_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		while (1)
 		{
-			if (isxdigit((unsigned char) *ptr))
+			int8 digit = hexlookup[(unsigned char) *ptr];
+
+			if (likely(digit >= 0))
 			{
 				if (unlikely(tmp > -(PG_INT16_MIN / 16)))
 					goto out_of_range;
 
-				tmp = tmp * 16 + hexlookup[(unsigned char) *ptr++];
+				tmp = tmp * 16 + digit;
+				ptr++;
 			}
 			else if (*ptr == '_')
 			{
@@ -165,14 +168,17 @@ pg_strtoint16_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		while (1)
 		{
-			if (*ptr >= '0' && *ptr <= '7')
+			unsigned char digit = *ptr - '0';
+
+			if (likely(digit < 8))
 			{
 				if (unlikely(tmp > -(PG_INT16_MIN / 8)))
 					goto out_of_range;
 
-				tmp = tmp * 8 + (*ptr++ - '0');
+				tmp = tmp * 8 + digit;
+				ptr++;
 			}
 			else if (*ptr == '_')
 			{
@@ -189,14 +195,17 @@ pg_strtoint16_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		while (1)
 		{
-			if (*ptr >= '0' && *ptr <= '1')
+			unsigned char digit = *ptr - '0';
+
+			if (likely(digit < 2))
 			{
 				if (unlikely(tmp > -(PG_INT16_MIN / 2)))
 					goto out_of_range;
 
-				tmp = tmp * 2 + (*ptr++ - '0');
+				tmp = tmp * 2 + digit;
+				ptr++;
 			}
 			else if (*ptr == '_')
 			{
@@ -213,14 +222,17 @@ pg_strtoint16_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr;
 
-		while (*ptr)
+		while (1)
 		{
-			if (isdigit((unsigned char) *ptr))
+			unsigned char digit = *ptr - '0';
+
+			if (likely(digit < 10))
 			{
 				if (unlikely(tmp > -(PG_INT16_MIN / 10)))
 					goto out_of_range;
 
-				tmp = tmp * 10 + (*ptr++ - '0');
+				tmp = tmp * 10 + digit;
+				ptr++;
 			}
 			else if (*ptr == '_')
 			{
@@ -302,7 +314,7 @@ pg_strtoint32_safe(const char *s, Node *escontext)
 	bool		neg = false;
 
 	/* skip leading spaces */
-	while (likely(*ptr) && isspace((unsigned char) *ptr))
+	while (isspace((unsigned char) *ptr))
 		ptr++;
 
 	/* handle sign */
@@ -319,14 +331,17 @@ pg_strtoint32_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		while (1)
 		{
-			if (isxdigit((unsigned char) *ptr))
+			int8 digit = hexlookup[(unsigned char) *ptr];
+
+			if (likely(digit >= 0))
 			{
 				if (unlikely(tmp > -(PG_INT32_MIN / 16)))
 					goto out_of_range;
 
-				tmp = tmp * 16 + hexlookup[(unsigned char) *ptr++];
+				tmp = tmp * 16 + digit;
+				ptr++;
 			}
 			else if (*ptr == '_')
 			{
@@ -343,14 +358,17 @@ pg_strtoint32_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		while (1)
 		{
-			if (*ptr >= '0' && *ptr <= '7')
+			unsigned char digit = *ptr - '0';
+
+			if (likely(digit < 8))
 			{
 				if (unlikely(tmp > -(PG_INT32_MIN / 8)))
 					goto out_of_range;
 
-				tmp = tmp * 8 + (*ptr++ - '0');
+				tmp = tmp * 8 + digit;
+				ptr++;
 			}
 			else if (*ptr == '_')
 			{
@@ -367,14 +385,17 @@ pg_strtoint32_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		while (1)
 		{
-			if (*ptr >= '0' && *ptr <= '1')
+			unsigned char digit = *ptr - '0';
+
+			if (likely(digit < 2))
 			{
 				if (unlikely(tmp > -(PG_INT32_MIN / 2)))
 					goto out_of_range;
 
-				tmp = tmp * 2 + (*ptr++ - '0');
+				tmp = tmp * 2 + digit;
+				ptr++;
 			}
 			else if (*ptr == '_')
 			{
@@ -391,14 +412,17 @@ pg_strtoint32_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr;
 
-		while (*ptr)
+		while (1)
 		{
-			if (isdigit((unsigned char) *ptr))
+			unsigned char digit = *ptr - '0';
+
+			if (likely(digit < 10))
 			{
 				if (unlikely(tmp > -(PG_INT32_MIN / 10)))
 					goto out_of_range;
 
-				tmp = tmp * 10 + (*ptr++ - '0');
+				tmp = tmp * 10 + digit;
+				ptr++;
 			}
 			else if (*ptr == '_')
 			{
@@ -420,7 +444,7 @@ 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'))
@@ -480,7 +504,7 @@ pg_strtoint64_safe(const char *s, Node *escontext)
 	bool		neg = false;
 
 	/* skip leading spaces */
-	while (*ptr && isspace((unsigned char) *ptr))
+	while (isspace((unsigned char) *ptr))
 		ptr++;
 
 	/* handle sign */
@@ -497,14 +521,17 @@ pg_strtoint64_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		while (1)
 		{
-			if (isxdigit((unsigned char) *ptr))
+			int8 digit = hexlookup[(unsigned char) *ptr];
+
+			if (likely(digit >= 0))
 			{
 				if (unlikely(tmp > -(PG_INT64_MIN / 16)))
 					goto out_of_range;
 
-				tmp = tmp * 16 + hexlookup[(unsigned char) *ptr++];
+				tmp = tmp * 16 + digit;
+				ptr++;
 			}
 			else if (*ptr == '_')
 			{
@@ -521,14 +548,17 @@ pg_strtoint64_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		while (1)
 		{
-			if (*ptr >= '0' && *ptr <= '7')
+			unsigned char digit = *ptr - '0';
+
+			if (likely(digit < 8))
 			{
 				if (unlikely(tmp > -(PG_INT64_MIN / 8)))
 					goto out_of_range;
 
-				tmp = tmp * 8 + (*ptr++ - '0');
+				tmp = tmp * 8 + digit;
+				ptr++;
 			}
 			else if (*ptr == '_')
 			{
@@ -545,14 +575,17 @@ pg_strtoint64_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr += 2;
 
-		while (*ptr)
+		while (1)
 		{
-			if (*ptr >= '0' && *ptr <= '1')
+			unsigned char digit = *ptr - '0';
+
+			if (likely(digit < 2))
 			{
 				if (unlikely(tmp > -(PG_INT64_MIN / 2)))
 					goto out_of_range;
 
-				tmp = tmp * 2 + (*ptr++ - '0');
+				tmp = tmp * 2 + digit;
+				ptr++;
 			}
 			else if (*ptr == '_')
 			{
@@ -569,14 +602,17 @@ pg_strtoint64_safe(const char *s, Node *escontext)
 	{
 		firstdigit = ptr;
 
-		while (*ptr)
+		while (1)
 		{
-			if (isdigit((unsigned char) *ptr))
+			unsigned char digit = *ptr - '0';
+
+			if (likely(digit < 10))
 			{
 				if (unlikely(tmp > -(PG_INT64_MIN / 10)))
 					goto out_of_range;
 
-				tmp = tmp * 10 + (*ptr++ - '0');
+				tmp = tmp * 10 + digit;
+				ptr++;
 			}
 			else if (*ptr == '_')
 			{
@@ -598,7 +634,7 @@ 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'))