gcov: Add TARGET_GCOV_TYPE_SIZE target hook

If -fprofile-update=atomic is used, then the target must provide atomic
operations for the counters of the type returned by get_gcov_type().
This is a 64-bit type for targets which have a 64-bit long long type.
On 32-bit targets this could be an issue since they may not provide
64-bit atomic operations.  Allow targets to override the default type
size with the new TARGET_GCOV_TYPE_SIZE target hook.

If a 32-bit gcov type size is used, then there is currently a warning in
libgcov-driver.c in a dead code block due to
sizeof (counter) == sizeof (gcov_unsigned_t):

libgcc/libgcov-driver.c: In function 'dump_counter':
libgcc/libgcov-driver.c:401:46: warning: right shift count >= width of type [-Wshift-count-overflow]
  401 |     dump_unsigned ((gcov_unsigned_t)(counter >> 32), dump_fn, arg);
      |                                              ^~

gcc/c-family/

	* c-cppbuiltin.c (c_cpp_builtins): Define
	__LIBGCC_GCOV_TYPE_SIZE if flag_building_libgcc is true.

gcc/

	* config/sparc/rtemself.h (SPARC_GCOV_TYPE_SIZE): Define.
	* config/sparc/sparc.c (sparc_gcov_type_size): New.
	(TARGET_GCOV_TYPE_SIZE): Redefine if SPARC_GCOV_TYPE_SIZE is defined.
	* coverage.c (get_gcov_type): Use targetm.gcov_type_size().
	* doc/tm.texi (TARGET_GCOV_TYPE_SIZE): Add hook under "Misc".
	* doc/tm.texi.in: Regenerate.
	* target.def (gcov_type_size): New target hook.
	* targhooks.c (default_gcov_type_size): New.
	* targhooks.h (default_gcov_type_size): Declare.
	* tree-profile.c (gimple_gen_edge_profiler): Use precision of
	gcov_type_node.
	(gimple_gen_time_profiler): Likewise.

libgcc/

	* libgcov.h (gcov_type): Define using __LIBGCC_GCOV_TYPE_SIZE.
	(gcov_type_unsigned): Likewise.

10 files changed, 52 insertions, 3 deletions

diff --git a/gcc/c-family/c-cppbuiltin.c b/gcc/c-family/c-cppbuiltin.c
index f79f939..3fa62bc 100644
--- a/gcc/c-family/c-cppbuiltin.c
+++ b/gcc/c-family/c-cppbuiltin.c
@@ -1450,6 +1450,8 @@ c_cpp_builtins (cpp_reader *pfile)
       /* For libgcov.  */
       builtin_define_with_int_value ("__LIBGCC_VTABLE_USES_DESCRIPTORS__",
 				     TARGET_VTABLE_USES_DESCRIPTORS);
+      builtin_define_with_int_value ("__LIBGCC_GCOV_TYPE_SIZE",
+				     targetm.gcov_type_size());
     }
 
   /* For use in assembly language.  */
diff --git a/gcc/config/sparc/rtemself.h b/gcc/config/sparc/rtemself.h
index fa972af..d64ce90 100644
--- a/gcc/config/sparc/rtemself.h
+++ b/gcc/config/sparc/rtemself.h
@@ -40,3 +40,5 @@
 
 /* Use the default */
 #undef LINK_GCC_C_SEQUENCE_SPEC
+
+#define SPARC_GCOV_TYPE_SIZE 32
diff --git a/gcc/config/sparc/sparc.c b/gcc/config/sparc/sparc.c
index 04fc80f..06f41d7 100644
--- a/gcc/config/sparc/sparc.c
+++ b/gcc/config/sparc/sparc.c
@@ -944,6 +944,17 @@ char sparc_hard_reg_printed[8];
 #undef TARGET_ZERO_CALL_USED_REGS
 #define TARGET_ZERO_CALL_USED_REGS sparc_zero_call_used_regs
 
+#ifdef SPARC_GCOV_TYPE_SIZE
+static HOST_WIDE_INT
+sparc_gcov_type_size (void)
+{
+  return SPARC_GCOV_TYPE_SIZE;
+}
+
+#undef TARGET_GCOV_TYPE_SIZE
+#define TARGET_GCOV_TYPE_SIZE sparc_gcov_type_size
+#endif
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 /* Return the memory reference contained in X if any, zero otherwise.  */
diff --git a/gcc/coverage.c b/gcc/coverage.c
index ac9a9fd..10d7f83 100644
--- a/gcc/coverage.c
+++ b/gcc/coverage.c
@@ -146,7 +146,7 @@ tree
 get_gcov_type (void)
 {
   scalar_int_mode mode
-    = smallest_int_mode_for_size (LONG_LONG_TYPE_SIZE > 32 ? 64 : 32);
+    = smallest_int_mode_for_size (targetm.gcov_type_size ());
   return lang_hooks.types.type_for_mode (mode, false);
 }
 
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index a30fdcb..f68f426 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -12588,3 +12588,14 @@ Return an RTX representing @var{tagged_pointer} with its tag set to zero.
 Store the result in @var{target} if convenient.
 The default clears the top byte of the original pointer.
 @end deftypefn
+
+@deftypefn {Target Hook} HOST_WIDE_INT TARGET_GCOV_TYPE_SIZE (void)
+Returns the gcov type size in bits.  This type is used for example for
+counters incremented by profiling and code-coverage events.  The default
+value is 64, if the type size of long long is greater than 32, otherwise the
+default value is 32.  A 64-bit type is recommended to avoid overflows of the
+counters.  If the @option{-fprofile-update=atomic} is used, then the
+counters are incremented using atomic operations.  Targets not supporting
+64-bit atomic operations may override the default value and request a 32-bit
+type.
+@end deftypefn
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 611fc50..fdf16b9 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -8180,3 +8180,5 @@ maintainer is familiar with.
 @hook TARGET_MEMTAG_EXTRACT_TAG
 
 @hook TARGET_MEMTAG_UNTAGGED_POINTER
+
+@hook TARGET_GCOV_TYPE_SIZE
diff --git a/gcc/target.def b/gcc/target.def
index 7676d5e..28a34f1 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -7104,6 +7104,18 @@ DEFHOOK
  void, (void),
  NULL)
 
+DEFHOOK
+(gcov_type_size,
+ "Returns the gcov type size in bits.  This type is used for example for\n\
+counters incremented by profiling and code-coverage events.  The default\n\
+value is 64, if the type size of long long is greater than 32, otherwise the\n\
+default value is 32.  A 64-bit type is recommended to avoid overflows of the\n\
+counters.  If the @option{-fprofile-update=atomic} is used, then the\n\
+counters are incremented using atomic operations.  Targets not supporting\n\
+64-bit atomic operations may override the default value and request a 32-bit\n\
+type.",
+ HOST_WIDE_INT, (void), default_gcov_type_size)
+
 /* Close the 'struct gcc_target' definition.  */
 HOOK_VECTOR_END (C90_EMPTY_HACK)
 
diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index eb51909..c9b5208 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -2654,4 +2654,11 @@ default_memtag_untagged_pointer (rtx tagged_pointer, rtx target)
   return untagged_base;
 }
 
+/* The default implementation of TARGET_GCOV_TYPE_SIZE.  */
+HOST_WIDE_INT
+default_gcov_type_size (void)
+{
+  return TYPE_PRECISION (long_long_integer_type_node) > 32 ? 64 : 32;
+}
+
 #include "gt-targhooks.h"
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index f92e102..92d5199 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -302,4 +302,6 @@ extern rtx default_memtag_set_tag (rtx, rtx, rtx);
 extern rtx default_memtag_extract_tag (rtx, rtx);
 extern rtx default_memtag_untagged_pointer (rtx, rtx);
 
+extern HOST_WIDE_INT default_gcov_type_size (void);
+
 #endif /* GCC_TARGHOOKS_H */
diff --git a/gcc/tree-profile.c b/gcc/tree-profile.c
index 5a74cc9..cf46912 100644
--- a/gcc/tree-profile.c
+++ b/gcc/tree-profile.c
@@ -250,7 +250,7 @@ gimple_gen_edge_profiler (int edgeno, edge e)
     {
       /* __atomic_fetch_add (&counter, 1, MEMMODEL_RELAXED); */
       tree addr = tree_coverage_counter_addr (GCOV_COUNTER_ARCS, edgeno);
-      tree f = builtin_decl_explicit (LONG_LONG_TYPE_SIZE > 32
+      tree f = builtin_decl_explicit (TYPE_PRECISION (gcov_type_node) > 32
 				      ? BUILT_IN_ATOMIC_FETCH_ADD_8:
 				      BUILT_IN_ATOMIC_FETCH_ADD_4);
       gcall *stmt = gimple_build_call (f, 3, addr, one,
@@ -525,7 +525,7 @@ gimple_gen_time_profiler (unsigned tag)
 			  tree_time_profiler_counter);
       gassign *assign = gimple_build_assign (ptr, NOP_EXPR, addr);
       gsi_insert_before (&gsi, assign, GSI_NEW_STMT);
-      tree f = builtin_decl_explicit (LONG_LONG_TYPE_SIZE > 32
+      tree f = builtin_decl_explicit (TYPE_PRECISION (gcov_type_node) > 32
 				      ? BUILT_IN_ATOMIC_ADD_FETCH_8:
 				      BUILT_IN_ATOMIC_ADD_FETCH_4);
       gcall *stmt = gimple_build_call (f, 3, ptr, one,