Add a target hook for getting an ABI from a function type

This patch adds a target hook that allows targets to return
the ABI associated with a particular function type.  Generally,
when multiple ABIs are in use, it must be possible to tell from
a function type and its attributes which ABI it is using.

2019-09-30  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* target.def (fntype_abi): New target hook.
	* doc/tm.texi.in (TARGET_FNTYPE_ABI): Likewise.
	* doc/tm.texi: Regenerate.
	* target.h (predefined_function_abi): Declare.
	* function-abi.cc (fntype_abi): Call targetm.calls.fntype_abi,
	if defined.
	* config/aarch64/aarch64.h (ARM_PCS_SIMD): New arm_pcs value.
	* config/aarch64/aarch64.c: Include function-abi.h.
	(aarch64_simd_abi, aarch64_fntype_abi): New functions.
	(TARGET_FNTYPE_ABI): Define.

From-SVN: r276308

gcc/ChangeLog

 2019-09-30  Richard Sandiford  <richard.sandiford@arm.com>
 
+	* target.def (fntype_abi): New target hook.
+	* doc/tm.texi.in (TARGET_FNTYPE_ABI): Likewise.
+	* doc/tm.texi: Regenerate.
+	* target.h (predefined_function_abi): Declare.
+	* function-abi.cc (fntype_abi): Call targetm.calls.fntype_abi,
+	if defined.
+	* config/aarch64/aarch64.h (ARM_PCS_SIMD): New arm_pcs value.
+	* config/aarch64/aarch64.c: Include function-abi.h.
+	(aarch64_simd_abi, aarch64_fntype_abi): New functions.
+	(TARGET_FNTYPE_ABI): Define.
+
+2019-09-30  Richard Sandiford  <richard.sandiford@arm.com>
+
 	* Makefile.in (OBJS): Add function-abi.o.
 	(GTFILES): Add function-abi.h.
 	* function-abi.cc: New file.

gcc/config/aarch64/aarch64.c

@@ -74,6 +74,7 @@
 #include "rtx-vector-builder.h"
 #include "intl.h"
 #include "expmed.h"
+#include "function-abi.h"
 
 /* This file should be included last.  */
 #include "target-def.h"
@@ -1365,6 +1366,24 @@ svpattern_token (enum aarch64_svpattern pattern)
   gcc_unreachable ();
 }
 
+/* Return the descriptor of the SIMD ABI.  */
+
+static const predefined_function_abi &
+aarch64_simd_abi (void)
+{
+  predefined_function_abi &simd_abi = function_abis[ARM_PCS_SIMD];
+  if (!simd_abi.initialized_p ())
+    {
+      HARD_REG_SET full_reg_clobbers
+	= default_function_abi.full_reg_clobbers ();
+      for (int regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
+	if (FP_SIMD_SAVED_REGNUM_P (regno))
+	  CLEAR_HARD_REG_BIT (full_reg_clobbers, regno);
+      simd_abi.initialize (ARM_PCS_SIMD, full_reg_clobbers);
+    }
+  return simd_abi;
+}
+
 /* Generate code to enable conditional branches in functions over 1 MiB.  */
 const char *
 aarch64_gen_far_branch (rtx * operands, int pos_label, const char * dest,
@@ -1810,6 +1829,16 @@ aarch64_hard_regno_mode_ok (unsigned regno, machine_mode mode)
   return false;
 }
 
+/* Implement TARGET_FNTYPE_ABI.  */
+
+static const predefined_function_abi &
+aarch64_fntype_abi (const_tree fntype)
+{
+  if (lookup_attribute ("aarch64_vector_pcs", TYPE_ATTRIBUTES (fntype)))
+    return aarch64_simd_abi ();
+  return default_function_abi;
+}
+
 /* Return true if this is a definition of a vectorized simd function.  */
 
 static bool
@@ -21024,6 +21053,9 @@ aarch64_libgcc_floating_mode_supported_p
 #undef TARGET_GET_MULTILIB_ABI_NAME
 #define TARGET_GET_MULTILIB_ABI_NAME aarch64_get_multilib_abi_name
 
+#undef TARGET_FNTYPE_ABI
+#define TARGET_FNTYPE_ABI aarch64_fntype_abi
+
 #if CHECKING_P
 #undef TARGET_RUN_TARGET_SELFTESTS
 #define TARGET_RUN_TARGET_SELFTESTS selftest::aarch64_run_selftests

gcc/config/aarch64/aarch64.h

@@ -783,6 +783,7 @@ enum aarch64_abi_type
 enum arm_pcs
 {
   ARM_PCS_AAPCS64,		/* Base standard AAPCS for 64 bit.  */
+  ARM_PCS_SIMD,			/* For aarch64_vector_pcs functions.  */
   ARM_PCS_UNKNOWN
 };
 

gcc/doc/tm.texi

@@ -1898,6 +1898,16 @@ must be defined.  Modern ports should define @code{CALL_REALLY_USED_REGISTERS}.
 @cindex call-used register
 @cindex call-clobbered register
 @cindex call-saved register
+@deftypefn {Target Hook} {const predefined_function_abi &} TARGET_FNTYPE_ABI (const_tree @var{type})
+Return the ABI used by a function with type @var{type}; see the
+definition of @code{predefined_function_abi} for details of the ABI
+descriptor.  Targets only need to define this hook if they support
+interoperability between several ABIs in the same translation unit.
+@end deftypefn
+
+@cindex call-used register
+@cindex call-clobbered register
+@cindex call-saved register
 @deftypefn {Target Hook} bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (rtx_insn *@var{insn}, unsigned int @var{regno}, machine_mode @var{mode})
 This hook should return true if @var{regno} is partly call-saved and
 partly call-clobbered, and if a value of mode @var{mode} would be partly

gcc/doc/tm.texi.in

@@ -1709,6 +1709,11 @@ must be defined.  Modern ports should define @code{CALL_REALLY_USED_REGISTERS}.
 @cindex call-used register
 @cindex call-clobbered register
 @cindex call-saved register
+@hook TARGET_FNTYPE_ABI
+
+@cindex call-used register
+@cindex call-clobbered register
+@cindex call-saved register
 @hook TARGET_HARD_REGNO_CALL_PART_CLOBBERED
 
 @hook TARGET_REMOVE_EXTRA_CALL_PRESERVED_REGS

gcc/function-abi.cc

@@ -132,6 +132,8 @@ const predefined_function_abi &
 fntype_abi (const_tree type)
 {
   gcc_assert (FUNC_OR_METHOD_TYPE_P (type));
+  if (targetm.calls.fntype_abi)
+    return targetm.calls.fntype_abi (type);
   return default_function_abi;
 }
 

gcc/target.def

@@ -4943,6 +4943,15 @@ If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.",
  bool, (const unsigned int regno),
  default_function_value_regno_p)
 
+DEFHOOK
+(fntype_abi,
+ "Return the ABI used by a function with type @var{type}; see the\n\
+definition of @code{predefined_function_abi} for details of the ABI\n\
+descriptor.  Targets only need to define this hook if they support\n\
+interoperability between several ABIs in the same translation unit.",
+ const predefined_function_abi &, (const_tree type),
+ NULL)
+
 /* ??? Documenting this hook requires a GFDL license grant.  */
 DEFHOOK_UNDOC
 (internal_arg_pointer,

gcc/target.h

@@ -152,6 +152,9 @@ class _stmt_vec_info;
 /* This is defined in calls.h.  */
 class function_arg_info;
 
+/* This is defined in function-abi.h.  */
+class predefined_function_abi;
+
 /* These are defined in tree-vect-stmts.c.  */
 extern tree stmt_vectype (class _stmt_vec_info *);
 extern bool stmt_in_inner_loop_p (class _stmt_vec_info *);