[flang] Main program symbol no longer conflicts with the other symbols (#149169)

The following code is now accepted:
```
module m
end
program m
use m
end
```
The PROGRAM name doesn't really have an effect on the compilation
result, so it shouldn't result in symbol name conflicts.

This change makes the main program symbol name all uppercase in the
cooked character stream. This makes it distinct from all other symbol
names that are all lowercase in cooked character stream.

Modified the tests that were checking for lower case main program name.

Author: eugeneepshteyn

flang/docs/Extensions.md

@@ -1,9 +1,9 @@
-<!--===- docs/Extensions.md 
-  
+<!--===- docs/Extensions.md
+
    Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
    See https://llvm.org/LICENSE.txt for license information.
    SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-  
+
 -->
 
 # Fortran Extensions supported by Flang
@@ -170,6 +170,18 @@ end
   In the case of `DEFERRED` bindings in an `ABSTRACT` derived type,
   however, overrides are necessary, so they are permitted for inaccessible
   bindings with an optional warning.
+* Main program name is allowed to be the same as the other symbols used
+  in the main program, for example:
+```
+module m
+end
+program m
+use m
+end
+```
+  Note that internally the main program symbol name is all uppercase, unlike
+  the names of all other symbols, which are usually all lowercase. This
+  may make a difference in testing/debugging.
 
 ## Extensions, deletions, and legacy features supported by default
 

flang/lib/Semantics/check-omp-structure.cpp

@@ -1156,8 +1156,7 @@ void OmpStructureChecker::CheckThreadprivateOrDeclareTargetVar(
                         (sym->has<MainProgramDetails>() ||
                             sym->has<ModuleDetails>())) {
                       context_.Say(name->source,
-                          "The module name or main program name cannot be in a "
-                          "%s "
+                          "The module name cannot be in a %s "
                           "directive"_err_en_US,
                           ContextDirectiveAsFortran());
                     } else if (!IsSaved(*name->symbol) &&

flang/lib/Semantics/resolve-labels.cpp

@@ -489,15 +489,30 @@ class ParseTreeAnalyzer {
 
   // C1401
   void Post(const parser::MainProgram &mainProgram) {
+    // Uppercase the name of the main program, so that its symbol name
+    // would be unique from similarly named non-main-program symbols.
+    auto upperCaseCharBlock = [](const parser::CharBlock &cb) {
+      char *ch{const_cast<char *>(cb.begin())};
+      char *endCh{ch + cb.size()};
+      while (ch != endCh) {
+        *ch++ = parser::ToUpperCaseLetter(*ch);
+      }
+    };
+    const parser::CharBlock *progName{nullptr};
+    if (const auto &program{
+            std::get<std::optional<parser::Statement<parser::ProgramStmt>>>(
+                mainProgram.t)}) {
+      progName = &program->statement.v.source;
+      upperCaseCharBlock(*progName);
+    }
     if (const parser::CharBlock *
         endName{GetStmtName(std::get<parser::Statement<parser::EndProgramStmt>>(
             mainProgram.t))}) {
-      if (const auto &program{
-              std::get<std::optional<parser::Statement<parser::ProgramStmt>>>(
-                  mainProgram.t)}) {
-        if (*endName != program->statement.v.source) {
+      upperCaseCharBlock(*endName);
+      if (progName) {
+        if (*endName != *progName) {
           context_.Say(*endName, "END PROGRAM name mismatch"_err_en_US)
-              .Attach(program->statement.v.source, "should be"_en_US);
+              .Attach(*progName, "should be"_en_US);
         }
       } else {
         context_.Say(*endName,

flang/test/Driver/cuda-option.f90

@@ -8,7 +8,7 @@ program main
   integer, device :: dvar
 end program
 
-! CHECK-LABEL: PROGRAM main
+! CHECK-LABEL: PROGRAM MAIN
 ! CHECK: INTEGER :: var = 1
 ! CHECK: INTEGER, DEVICE :: dvar
 

flang/test/Driver/unparse-use-analyzed.f95

@@ -6,12 +6,12 @@
 ! RUN: %flang_fc1 -fdebug-unparse  %s | FileCheck %s --check-prefix=DEFAULT
 ! RUN: %flang_fc1 -fdebug-unparse -fno-analyzed-objects-for-unparse %s | FileCheck %s --check-prefix=DISABLED
 
-! DEFAULT: PROGRAM test
+! DEFAULT: PROGRAM TEST
 ! DEFAULT-NEXT:  REAL, PARAMETER :: val = 3.43e2_4
 ! DEFAULT-NEXT:  PRINT *, 3.47e2_4
 ! DEFAULT-NEXT: END PROGRAM
 
-! DISABLED: PROGRAM test
+! DISABLED: PROGRAM TEST
 ! DISABLED-NEXT:  REAL, PARAMETER :: val = 343.0
 ! DISABLED-NEXT:  PRINT *, val+4
 ! DISABLED-NEXT: END PROGRAM

flang/test/Driver/unparse-with-modules.f90

@@ -25,7 +25,7 @@ program test
 !CHECK:  implicit none
 !CHECK:  real(kind=real32) x
 !CHECK: end module
-!CHECK: program test
+!CHECK: program TEST
 !CHECK:  use :: m1
 !CHECK:  use :: basictestmoduletwo
 !CHECK:  implicit none

flang/test/Integration/debug-common-block-1.f90

@@ -89,7 +89,7 @@ program test
 ! CHECK-DAG: ![[CBF3]] = !DICommonBlock(scope: ![[F3]], declaration: null, name: "__BLNK__"{{.*}})
 ! CHECK-DAG: ![[CBAF3]] = !DICommonBlock(scope: ![[F3]], declaration: null, name: "a"{{.*}})
 
-! CHECK-DAG: ![[MAIN:[0-9]+]] = {{.*}}!DISubprogram(name: "test"{{.*}})
+! CHECK-DAG: ![[MAIN:[0-9]+]] = {{.*}}!DISubprogram(name: "TEST"{{.*}})
 ! CHECK-DAG: ![[CBM]] = !DICommonBlock(scope: ![[MAIN]], declaration: null, name: "__BLNK__"{{.*}})
 ! CHECK-DAG: ![[CBAM]] = !DICommonBlock(scope: ![[MAIN]], declaration: null, name: "a"{{.*}})
 

flang/test/Integration/debug-local-var-2.f90

@@ -37,7 +37,7 @@
 ! BOTH-LABEL: }
 
 program mn
-! BOTH-DAG: ![[MAIN:.*]] = distinct !DISubprogram(name: "mn", {{.*}})
+! BOTH-DAG: ![[MAIN:.*]] = distinct !DISubprogram(name: "MN", {{.*}})
 
 ! BOTH-DAG: ![[TYI32:.*]] = !DIBasicType(name: "integer", size: 32, encoding: DW_ATE_signed)
 ! BOTH-DAG: ![[TYI64:.*]] = !DIBasicType(name: "integer", size: 64, encoding: DW_ATE_signed)

flang/test/Lower/CUDA/cuda-derived.cuf

@@ -25,6 +25,6 @@ program main
   type(t2) :: b
 end
 
-! CHECK-LABEL: func.func @_QQmain() attributes {fir.bindc_name = "main"}
+! CHECK-LABEL: func.func @_QQmain() attributes {fir.bindc_name = "MAIN"}
 ! CHECK: %{{.*}} = cuf.alloc !fir.type<_QMm1Tty_device{x:!fir.box<!fir.heap<!fir.array<?xi32>>>}> {bindc_name = "a", data_attr = #cuf.cuda<managed>, uniq_name = "_QFEa"}
 ! CHECK: %{{.*}} = cuf.alloc !fir.type<_QMm1Tt2{b:!fir.type<_QMm1Tt1{a:!fir.box<!fir.heap<!fir.array<?xf32>>>}>}> {bindc_name = "b", data_attr = #cuf.cuda<managed>, uniq_name = "_QFEb"}

flang/test/Lower/CUDA/cuda-return01.cuf

@@ -28,6 +28,6 @@ program main
   return
 end
 
-! CHECK-LABEL: func.func @_QQmain() attributes {fir.bindc_name = "main"}
+! CHECK-LABEL: func.func @_QQmain() attributes {fir.bindc_name = "MAIN"}
 ! CHECK: cuf.alloc !fir.box<!fir.heap<!fir.array<?xi32>>> {bindc_name = "a", data_attr = #cuf.cuda<device>, uniq_name = "_QFEa"} -> !fir.ref<!fir.box<!fir.heap<!fir.array<?xi32>>>>
 ! CHECK-NOT: cuf.free