rust: Reintroduce TARGET_RUST_CPU_INFO hook

gcc/ChangeLog:

	* doc/tm.texi: Regenerate.
	* doc/tm.texi.in: Add @node for Rust language and ABI, and document
	TARGET_RUST_CPU_INFO.

gcc/rust/ChangeLog:

	* rust-lang.cc (rust_add_target_info): Remove sorry.
	* rust-session-manager.cc: Replace include of target.h with
	include of tm.h and rust-target.h.
	(Session::init): Call targetrustm.rust_cpu_info.
	* rust-target.def (rust_cpu_info): New hook.
	* rust-target.h (rust_add_target_info): Declare.

6 files changed, 42 insertions, 3 deletions

diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 69123f0..f7a2f8b 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -53,6 +53,7 @@ through the macros defined in the @file{.h} file.
 * PCH Target::          Validity checking for precompiled headers.
 * C++ ABI::             Controlling C++ ABI changes.
 * D Language and ABI::  Controlling D ABI changes.
+* Rust Language and ABI:: Controlling Rust ABI changes.
 * Named Address Spaces:: Adding support for named address spaces
 * Misc::                Everything else.
 @end menu
@@ -10962,6 +10963,18 @@ if they have external linkage.  If this flag is false, then instantiated
 decls will be emitted as weak symbols.  The default is @code{false}.
 @end deftypevr
 
+@node Rust Language and ABI
+@section Rust ABI parameters
+@cindex parameters, rust abi
+
+@deftypefn {Rust Target Hook} void TARGET_RUST_CPU_INFO (void)
+Declare all environmental CPU info and features relating to the target CPU
+using the function @code{rust_add_target_info}, which takes a string
+representing the feature key and a string representing the feature value.
+Configuration pairs predefined by this hook apply to all files that are being
+compiled.
+@end deftypefn
+
 @node Named Address Spaces
 @section Adding support for named address spaces
 @cindex named address spaces
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 9bac02b..cd4e687 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -53,6 +53,7 @@ through the macros defined in the @file{.h} file.
 * PCH Target::          Validity checking for precompiled headers.
 * C++ ABI::             Controlling C++ ABI changes.
 * D Language and ABI::  Controlling D ABI changes.
+* Rust Language and ABI:: Controlling Rust ABI changes.
 * Named Address Spaces:: Adding support for named address spaces
 * Misc::                Everything else.
 @end menu
@@ -7143,6 +7144,12 @@ floating-point support; they are not included in this mechanism.
 
 @hook TARGET_D_TEMPLATES_ALWAYS_COMDAT
 
+@node Rust Language and ABI
+@section Rust ABI parameters
+@cindex parameters, rust abi
+
+@hook TARGET_RUST_CPU_INFO
+
 @node Named Address Spaces
 @section Adding support for named address spaces
 @cindex named address spaces
diff --git a/gcc/rust/rust-lang.cc b/gcc/rust/rust-lang.cc
index 1fb1c25..978b8b9 100644
--- a/gcc/rust/rust-lang.cc
+++ b/gcc/rust/rust-lang.cc
@@ -101,8 +101,6 @@ struct GTY (()) language_function
 void
 rust_add_target_info (const char *key, const char *value)
 {
-  sorry ("TODO");
-
   Rust::Session::get_instance ().options.target_data.insert_key_value_pair (
     key, value);
 }
diff --git a/gcc/rust/rust-session-manager.cc b/gcc/rust/rust-session-manager.cc
index 074bad9..112960a 100644
--- a/gcc/rust/rust-session-manager.cc
+++ b/gcc/rust/rust-session-manager.cc
@@ -44,7 +44,8 @@
 #include "diagnostic.h"
 #include "input.h"
 #include "selftest.h"
-#include "target.h"
+#include "tm.h"
+#include "rust-target.h"
 
 extern bool
 saw_errors (void);
@@ -137,6 +138,10 @@ validate_crate_name (const std::string &crate_name, Error &error)
 void
 Session::init ()
 {
+  // initialize target hooks
+  targetrustm.rust_cpu_info ();
+
+  // target-independent values that should exist in all targets
   options.target_data.insert_key_value_pair ("target_pointer_width",
 					     std::to_string (POINTER_SIZE));
   options.target_data.insert_key_value_pair ("target_endian", BYTES_BIG_ENDIAN
diff --git a/gcc/rust/rust-target.def b/gcc/rust/rust-target.def
index c800eef..285b7503 100644
--- a/gcc/rust/rust-target.def
+++ b/gcc/rust/rust-target.def
@@ -28,5 +28,17 @@ HOOK_VECTOR (TARGETRUSTM_INITIALIZER, gcc_targetrustm)
 #undef HOOK_PREFIX
 #define HOOK_PREFIX "TARGET_"
 
+/* Environmental CPU info and features (e.g. endianness, pointer size) relating
+   to the target CPU.  */
+DEFHOOK
+(rust_cpu_info,
+ "Declare all environmental CPU info and features relating to the target CPU\n\
+using the function @code{rust_add_target_info}, which takes a string\n\
+representing the feature key and a string representing the feature value.\n\
+Configuration pairs predefined by this hook apply to all files that are being\n\
+compiled.",
+ void, (void),
+ hook_void_void)
+
 /* Close the 'struct gcc_targetrustm' definition.  */
 HOOK_VECTOR_END (C90_EMPTY_HACK)
diff --git a/gcc/rust/rust-target.h b/gcc/rust/rust-target.h
index 79edd78..7fcdfc9 100644
--- a/gcc/rust/rust-target.h
+++ b/gcc/rust/rust-target.h
@@ -25,6 +25,10 @@
 
 #include "rust-target.def"
 
+/* Used by target to add target-related info.  */
+extern void
+rust_add_target_info (const char *, const char *);
+
 /* Each target can provide their own.  */
 extern struct gcc_targetrustm targetrustm;