[OpenMP] Add a few small fixes

* Add comment to help ensure new construct data are added in two places
* Check for division by zero in the loop worksharing code
* Check for syntax errors in parrange parsing

Differential Revision: https://reviews.llvm.org/D105929

Author: jpeyton52

openmp/runtime/src/kmp.h

@@ -1439,6 +1439,8 @@ __kmp_mm_mwait(unsigned extensions, unsigned hints) {
 /* Support datatypes for the orphaned construct nesting checks.             */
 /* ------------------------------------------------------------------------ */
 
+/* When adding to this enum, add its corresponding string in cons_text_c[]
+ * array in kmp_error.cpp */
 enum cons_type {
   ct_none,
   ct_parallel,

openmp/runtime/src/kmp_dispatch.cpp

@@ -561,6 +561,7 @@ void __kmp_dispatch_init_algorithm(ident_t *loc, int gtid,
         _control87(_PC_64, _MCW_PC); // 0,0x30000
 #endif
         /* value used for comparison in solver for cross-over point */
+        KMP_ASSERT(tc > 0);
         long double target = ((long double)chunk * 2 + 1) * nproc / tc;
 
         /* crossover point--chunk indexes equal to or greater than
@@ -1715,7 +1716,7 @@ int __kmp_dispatch_next_algorithm(int gtid,
         status = 0; // nothing to do, don't try atomic op
         break;
       }
-      KMP_DEBUG_ASSERT(init % chunk == 0);
+      KMP_DEBUG_ASSERT(chunk && init % chunk == 0);
       // compare with K*nproc*(chunk+1), K=2 by default
       if ((T)remaining < pr->u.p.parm2) {
         // use dynamic-style schedule

openmp/runtime/src/kmp_settings.cpp

@@ -431,6 +431,7 @@ static void __kmp_stg_parse_par_range(char const *name, char const *value,
                                       int *out_range, char *out_routine,
                                       char *out_file, int *out_lb,
                                       int *out_ub) {
+  const char *par_range_value;
   size_t len = KMP_STRLEN(value) + 1;
   par_range_to_print = (char *)KMP_INTERNAL_MALLOC(len + 1);
   KMP_STRNCPY_S(par_range_to_print, len + 1, value, len + 1);
@@ -439,11 +440,14 @@ static void __kmp_stg_parse_par_range(char const *name, char const *value,
   __kmp_par_range_ub = INT_MAX;
   for (;;) {
     unsigned int len;
-    if (*value == '\0') {
+    if (!value || *value == '\0') {
       break;
     }
     if (!__kmp_strcasecmp_with_sentinel("routine", value, '=')) {
-      value = strchr(value, '=') + 1;
+      par_range_value = strchr(value, '=') + 1;
+      if (!par_range_value)
+        goto par_range_error;
+      value = par_range_value;
       len = __kmp_readstr_with_sentinel(out_routine, value,
                                         KMP_PAR_RANGE_ROUTINE_LEN - 1, ',');
       if (len == 0) {
@@ -456,7 +460,10 @@ static void __kmp_stg_parse_par_range(char const *name, char const *value,
       continue;
     }
     if (!__kmp_strcasecmp_with_sentinel("filename", value, '=')) {
-      value = strchr(value, '=') + 1;
+      par_range_value = strchr(value, '=') + 1;
+      if (!par_range_value)
+        goto par_range_error;
+      value = par_range_value;
       len = __kmp_readstr_with_sentinel(out_file, value,
                                         KMP_PAR_RANGE_FILENAME_LEN - 1, ',');
       if (len == 0) {
@@ -470,7 +477,10 @@ static void __kmp_stg_parse_par_range(char const *name, char const *value,
     }
     if ((!__kmp_strcasecmp_with_sentinel("range", value, '=')) ||
         (!__kmp_strcasecmp_with_sentinel("incl_range", value, '='))) {
-      value = strchr(value, '=') + 1;
+      par_range_value = strchr(value, '=') + 1;
+      if (!par_range_value)
+        goto par_range_error;
+      value = par_range_value;
       if (KMP_SSCANF(value, "%d:%d", out_lb, out_ub) != 2) {
         goto par_range_error;
       }
@@ -482,7 +492,10 @@ static void __kmp_stg_parse_par_range(char const *name, char const *value,
       continue;
     }
     if (!__kmp_strcasecmp_with_sentinel("excl_range", value, '=')) {
-      value = strchr(value, '=') + 1;
+      par_range_value = strchr(value, '=') + 1;
+      if (!par_range_value)
+        goto par_range_error;
+      value = par_range_value;
       if (KMP_SSCANF(value, "%d:%d", out_lb, out_ub) != 2) {
         goto par_range_error;
       }