[Flang] [OpenMP] Add support for spaces in between the name (#168311)

Supports the fixed form syntax which has spaces in between the
identifier

Author: Thirumalai-Shaktivel

flang/lib/Parser/prescan.cpp

@@ -845,6 +845,9 @@ bool Prescanner::NextToken(TokenSequence &tokens) {
     if (InFixedFormSource()) {
       SkipSpaces();
     }
+    if (inFixedForm_ && (IsOpenMPDirective() && parenthesisNesting_ > 0)) {
+      SkipSpaces();
+    }
     if ((*at_ == '\'' || *at_ == '"') &&
         tokens.CharAt(tokens.SizeInChars() - 1) == '_') { // kind_"..."
       QuotedCharacterLiteral(tokens, start);

flang/lib/Parser/prescan.h

@@ -183,6 +183,9 @@ class Prescanner {
   bool InConditionalLine() const {
     return InOpenMPConditionalLine() || InOpenACCOrCUDAConditionalLine();
   }
+  bool IsOpenMPDirective() const {
+    return directiveSentinel_ && std::strcmp(directiveSentinel_, "$omp") == 0;
+  }
   bool InFixedFormSource() const {
     return inFixedForm_ && !inPreprocessorDirective_ && !InCompilerDirective();
   }

flang/test/Parser/OpenMP/name-with-space.f

@@ -0,0 +1,15 @@
+! RUN: %flang_fc1 -fopenmp -fdebug-unparse-no-sema %s 2>&1 | FileCheck %s
+
+        program name_with_space
+!CHECK: !$OMP THREADPRIVATE(/cc/, var1)
+!$omp threadprivate(/c c/, var 1)
+
+!CHECK: !$OMP PARALLEL PRIVATE(somevar,expr1,expr2) IF(expr2>expr1)
+!$omp parallel private(some var, expr 1, ex pr2)
+!$omp+ if (exp r2 > ex pr1)
+!$omp critical (x_x)
+        print '(a)', 'Hello World'
+!CHECK: !$OMP END CRITICAL(x_x)
+!$omp end critical (x _x)
+!$omp end parallel
+        end program name_with_space