Support for 64-bit location_t: Activate 64-bit location_t

Change location_t to be a 64-bit integer instead of a 32-bit integer in
libcpp.

Also included in this change are the two other patches in the original
series which depended on this one; I am committing them all at once in case
it needs to be reverted later:

-Support for 64-bit location_t: gimple parts

The size of struct gimple increased by 8 bytes with the change in size of
location_t from 32- to 64-bit; adjust the WORD markings in the comments
accordingly. It seems that most of the WORD markings were off by one already,
probably not having been updated after a previous reduction in the size of a
gimple, so they have become retroactively correct again, and only a couple
needed adjustment actually.

Also add a comment that there is now 32 bits of unused padding available in
struct gimple for 64-bit hosts.

-Support for 64-bit location_t: Remove -flarge-source-files

The option -flarge-source-files became unnecessary with 64-bit location_t
and harms performance compared to the new default setting, so silently
ignore it.

libcpp/ChangeLog:

	* include/cpplib.h (struct cpp_token): Adjust comment about the
	struct size.
	* include/line-map.h (location_t): Change typedef from 32-bit to 64-bit
	integer.
	(LINE_MAP_MAX_COLUMN_NUMBER): Increase size to be appropriate for
	64-bit location_t.
	(LINE_MAP_MAX_LOCATION_WITH_PACKED_RANGES): Likewise.
	(LINE_MAP_MAX_LOCATION_WITH_COLS): Likewise.
	(LINE_MAP_MAX_LOCATION): Likewise.
	(MAX_LOCATION_T): Likewise.
	(line_map_suggested_range_bits): Likewise.
	(struct line_map): Adjust comment about the struct size.
	(struct line_map_macro): Likewise.
	(struct line_map_ordinary): Likewise. Rearrange fields to optimize
	padding.

gcc/testsuite/ChangeLog:

	* g++.dg/diagnostic/pr77949.C: Adapt the test for 64-bit location_t,
	when the previously expected failure doesn't actually happen.
	* g++.dg/modules/loc-prune-4.C: Adjust the expected output for the
	64-bit location_t case.
	* gcc.dg/plugin/expensive_selftests_plugin.cc: Don't try to test
	the maximum supported column number in 64-bit location_t mode.
	* gcc.dg/plugin/location_overflow_plugin.cc: Adjust the base_location
	so it can effectively test 64-bit location_t.

gcc/ChangeLog:

	* gimple.h (struct gphi): Update word marking comments to reflect
	the new size of location_t.
	(struct gimple): Likewise. Add a comment about padding.
	* common.opt: Mark -flarge-source-files as Ignored.
	* common.opt.urls: Regenerate.
	* doc/invoke.texi: Remove -flarge-source-files.
	* toplev.cc (process_options): Remove support for
	-flarge-source-files.

2 files changed, 34 insertions, 22 deletions

diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index 298b434698a..10f07250135 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -255,8 +255,10 @@ struct GTY(()) cpp_identifier {
        spelling;
 };
 
-/* A preprocessing token.  This has been carefully packed and should
-   occupy 16 bytes on 32-bit hosts and 24 bytes on 64-bit hosts.  */
+/* A preprocessing token.  This occupies 32 bytes on a 64-bit host.  On a
+   32-bit host it occupies 20 or 24 bytes, depending whether a uint64_t
+   requires 4- or 8-byte alignment.  */
+
 struct GTY(()) cpp_token {
 
   /* Location of first char of token, together with range of full token.  */
diff --git a/libcpp/include/line-map.h b/libcpp/include/line-map.h
index 96fdf60644f..95cc09d900b 100644
--- a/libcpp/include/line-map.h
+++ b/libcpp/include/line-map.h
@@ -291,7 +291,10 @@ enum lc_reason
 
    To further see how location_t works in practice, see the
    worked example in libcpp/location-example.txt.  */
-typedef unsigned int location_t;
+
+/* A 64-bit type to represent a location.  We only use 63 of the 64 bits, so
+   that two location_t can be safely subtracted and stored in an int64_t.  */
+typedef uint64_t location_t;
 typedef int64_t location_diff_t;
 
 /* Sometimes we need a type that has the same size as location_t but that does
@@ -302,24 +305,31 @@ typedef location_t line_map_uint_t;
 /* Do not track column numbers higher than this one.  As a result, the
    range of column_bits is [12, 18] (or 0 if column numbers are
    disabled).  */
-const unsigned int LINE_MAP_MAX_COLUMN_NUMBER = (1U << 12);
+const unsigned int LINE_MAP_MAX_COLUMN_NUMBER = (1U << 31) - 1;
 
 /* Do not pack ranges if locations get higher than this.
    If you change this, update:
      gcc.dg/plugin/location-overflow-test-*.c.  */
-const location_t LINE_MAP_MAX_LOCATION_WITH_PACKED_RANGES = 0x50000000;
+const location_t LINE_MAP_MAX_LOCATION_WITH_PACKED_RANGES
+  = location_t (0x50000000) << 31;
 
 /* Do not track column numbers if locations get higher than this.
    If you change this, update:
      gcc.dg/plugin/location-overflow-test-*.c.  */
-const location_t LINE_MAP_MAX_LOCATION_WITH_COLS = 0x60000000;
+const location_t LINE_MAP_MAX_LOCATION_WITH_COLS
+  = location_t (0x60000000) << 31;
+
+/* Highest possible source location encoded within an ordinary map.  Higher
+   values up to MAX_LOCATION_T represent macro virtual locations.  */
+const location_t LINE_MAP_MAX_LOCATION = location_t (0x70000000) << 31;
 
-/* Highest possible source location encoded within an ordinary map.  */
-const location_t LINE_MAP_MAX_LOCATION = 0x70000000;
+/* This is the highest possible source location encoded within an
+   ordinary or macro map.  */
+const location_t MAX_LOCATION_T = location_t (-1) >> 2;
 
 /* This is the number of range bits suggested to enable, if range tracking is
    desired.  */
-const int line_map_suggested_range_bits = 5;
+const int line_map_suggested_range_bits = 7;
 
 /* A range of source locations.
 
@@ -397,7 +407,7 @@ typedef size_t (*line_map_round_alloc_size_func) (size_t);
 struct GTY((tag ("0"), desc ("MAP_ORDINARY_P (&%h) ? 1 : 2"))) line_map {
   location_t start_location;
 
-  /* Size and alignment is (usually) 4 bytes.  */
+  /* Size is 8 bytes; alignment 4 or 8 depending on the arch.  */
 };
 
 /* An ordinary line map encodes physical source locations. Those
@@ -413,7 +423,7 @@ struct GTY((tag ("0"), desc ("MAP_ORDINARY_P (&%h) ? 1 : 2"))) line_map {
 
    The highest possible source location is MAX_LOCATION_T.  */
 struct GTY((tag ("1"))) line_map_ordinary : public line_map {
-  /* Base class is 4 bytes.  */
+  /* Base class is 8 bytes.  */
 
   /* 4 bytes of integers, each 1 byte for easy extraction/insertion.  */
 
@@ -445,9 +455,7 @@ struct GTY((tag ("1"))) line_map_ordinary : public line_map {
      +-------------------------+-----------------------+-------------------+ */
   unsigned int m_range_bits : 8;
 
-  /* Pointer alignment boundary on both 32 and 64-bit systems.  */
-
-  const char *to_file;
+  /* 32-bit int even in 64-bit mode.  */
   linenum_type to_line;
 
   /* Location from whence this line map was included.  For regular
@@ -456,12 +464,11 @@ struct GTY((tag ("1"))) line_map_ordinary : public line_map {
      within a map.  */
   location_t included_from;
 
-  /* Size is 20 or 24 bytes, no padding  */
-};
+  /* Pointer alignment boundary, whether 32-bit or 64-bit mode.  */
+  const char *to_file;
 
-/* This is the highest possible source location encoded within an
-   ordinary or macro map.  */
-const location_t MAX_LOCATION_T = 0x7FFFFFFF;
+  /* Size is 28 (32) bytes for 32-bit (64-bit) arch.  */
+};
 
 struct cpp_hashnode;
 
@@ -480,7 +487,7 @@ struct GTY((tag ("2"))) line_map_macro : public line_map {
     return m_expansion;
   }
 
-  /* Base is 4 bytes.  */
+  /* Base is 8 bytes.  */
 
   /* The number of tokens inside the replacement-list of MACRO.  */
   unsigned int n_tokens;
@@ -556,7 +563,10 @@ struct GTY((tag ("2"))) line_map_macro : public line_map {
      if we are in a nested expansion context not.  */
   location_t m_expansion;
 
-  /* Size is 20 or 32 (4 bytes padding on 64-bit).  */
+  /* Size is one of the following:
+     32-bit system: 28 or 32 bytes, depending whether a uint64_t requires
+		    4- or 8-byte alignment.
+     64-bit arch: 40 bytes.  */
 };
 
 #if CHECKING_P && (GCC_VERSION >= 2007)
@@ -783,7 +793,7 @@ struct htab;
 
    The new adhoc_loc uses the highest bit as the enabling bit, i.e. if the
    highest bit is 1, then the number is adhoc_loc. Otherwise, it serves as
-   the original location. Once identified as the adhoc_loc, the lower 31
+   the original location.  Once identified as the adhoc_loc, the lower 62
    bits of the integer is used to index the location_adhoc_data array,
    in which the locus and associated data is stored.  */