add a new option -flarge-source-files.

gcc/ChangeLog:

	PR c/94230
	* common.opt: Add -flarge-source-files.
	* doc/invoke.texi: Document it.
	* toplev.c (process_options): set line_table->default_range_bits
	to 0 when flag_large_source_files is true.

gcc/c-family/ChangeLog:

	PR c/94230
	* c-indentation.c (get_visual_column): Add a hint to use the new
	-flarge-source-files option.

gcc/testsuite/ChangeLog:

	PR c/94230
	* gcc.dg/plugin/location-overflow-test-1.c (fn_1): New message to
	provide hint to use the new -flarge-source-files option.

8 files changed, 51 insertions, 3 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index bc27083..18800ec 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2020-05-06  qing zhao  <qing.zhao@oracle.com>
+
+	PR c/94230
+	* common.opt: Add -flarge-source-files.
+	* doc/invoke.texi: Document it.
+	* toplev.c (process_options): set line_table->default_range_bits
+	to 0 when flag_large_source_files is true.
+
 2020-05-06  Uroš Bizjak  <ubizjak@gmail.com>
 
 	PR target/94913
diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index fe6cfe7..a7faf829b 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,9 @@
+2020-05-06  qing zhao  <qing.zhao@oracle.com>
+
+	PR c/94230
+	* c-indentation.c (get_visual_column): Add a hint to use the new
+	-flarge-source-files option.
+
 2020-05-05  Stefan Schulze Frielinghaus  <stefansf@linux.ibm.com>
 
 	* c-attribs.c (handle_vector_size_attribute): Add attribute
diff --git a/gcc/c-family/c-indentation.c b/gcc/c-family/c-indentation.c
index f737555..9fba3bc 100644
--- a/gcc/c-family/c-indentation.c
+++ b/gcc/c-family/c-indentation.c
@@ -67,6 +67,11 @@ get_visual_column (expanded_location exploc, location_t loc,
 		  "%<-Wmisleading-indentation%> is disabled from this point"
 		  " onwards, since column-tracking was disabled due to"
 		  " the size of the code/headers");
+	  if (!flag_large_source_files)
+	    inform (loc,
+		    "adding %<-flarge-source-files%> will allow for more" 
+		    " column-tracking support, at the expense of compilation"
+		    " time and memory");
 	}
       return false;
     }
diff --git a/gcc/common.opt b/gcc/common.opt
index d33383b..30d0573 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1609,6 +1609,11 @@ fkeep-gc-roots-live
 Common Undocumented Report Var(flag_keep_gc_roots_live) Optimization
 ; Always keep a pointer to a live memory block
 
+flarge-source-files
+Common Report Var(flag_large_source_files) Init(0)
+Improve GCC's ability to track column numbers in large source files,
+at the expense of slower compilation.
+
 floop-parallelize-all
 Common Report Var(flag_loop_parallelize_all) Optimization
 Mark all loops as parallel.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 3537a81..c97318f 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -574,8 +574,8 @@ Objective-C and Objective-C++ Dialects}.
 -dD  -dI  -dM  -dN  -dU @gol
 -fdebug-cpp  -fdirectives-only  -fdollars-in-identifiers  @gol
 -fexec-charset=@var{charset}  -fextended-identifiers  @gol
--finput-charset=@var{charset}  -fmacro-prefix-map=@var{old}=@var{new}  @gol
--fmax-include-depth=@var{depth} @gol
+-finput-charset=@var{charset}  -flarge-source-files  @gol
+-fmacro-prefix-map=@var{old}=@var{new} -fmax-include-depth=@var{depth} @gol
 -fno-canonical-system-headers  -fpch-deps  -fpch-preprocess  @gol
 -fpreprocessed  -ftabstop=@var{width}  -ftrack-macro-expansion  @gol
 -fwide-exec-charset=@var{charset}  -fworking-directory @gol
@@ -14174,6 +14174,21 @@ This option may be useful in conjunction with the @option{-B} or
 perform additional processing of the program source between
 normal preprocessing and compilation.
 
+@item -flarge-source-files
+@opindex flarge-source-files
+Adjust GCC to expect large source files, at the expense of slower
+compilation and higher memory usage.
+
+Specifically, GCC normally tracks both column numbers and line numbers
+within source files and it normally prints both of these numbers in
+diagnostics.  However, once it has processed a certain number of source
+lines, it stops tracking column numbers and only tracks line numbers.
+This means that diagnostics for later lines do not include column numbers.
+It also means that options like @option{-Wmisleading-indentation} cease to work
+at that point, although the compiler prints a note if this happens.
+Passing @option{-flarge-source-files} significantly increases the number
+of source lines that GCC can process before it stops tracking columns.
+
 @end table
 
 @node Assembler Options
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index ccdbf98..6aa4378 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2020-05-06  qing zhao  <qing.zhao@oracle.com>
+
+	PR c/94230
+	* gcc.dg/plugin/location-overflow-test-1.c (fn_1): New message to 
+	provide hint to use the new -flarge-source-files option.
+
 2020-05-06  Uroš Bizjak  <ubizjak@gmail.com>
 
 	PR target/94913
diff --git a/gcc/testsuite/gcc.dg/plugin/location-overflow-test-1.c b/gcc/testsuite/gcc.dg/plugin/location-overflow-test-1.c
index 1a80a66..a3ac12d 100644
--- a/gcc/testsuite/gcc.dg/plugin/location-overflow-test-1.c
+++ b/gcc/testsuite/gcc.dg/plugin/location-overflow-test-1.c
@@ -13,7 +13,7 @@ int
 fn_1 (int flag)
 {
   int x = 4, y = 5;
-  if (flag) x = 3; y = 2; /* { dg-message "-:disabled from this point" } */
+  if (flag) x = 3; y = 2; /* { dg-message "-:disabled from this point" "adding '-flarge-source-files'" } */
   return x * y;
 }
 
diff --git a/gcc/toplev.c b/gcc/toplev.c
index 5c026fe..96316fb 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -1854,6 +1854,9 @@ process_options (void)
     hash_table_sanitize_eq_limit
       = param_hash_table_verification_limit;
 
+  if (flag_large_source_files)
+    line_table->default_range_bits = 0;
+
   /* Please don't change global_options after this point, those changes won't
      be reflected in optimization_{default,current}_node.  */
 }