Use checking forms of DECL_FUNCTION_CODE (PR 91421)

We were shoe-horning all built-in enumerations (including frontend
and target-specific ones) into a field of type built_in_function.  This
was accessed as either an lvalue or an rvalue using DECL_FUNCTION_CODE.

The obvious danger with this (as was noted by several ??? comments)
is that the ranges have nothing to do with each other, and targets can
easily have more built-in functions than generic code.  But my patch to
make the field bigger was the straw that finally made the problem visible.

This patch therefore:

- replaces the field with a plain unsigned int

- turns DECL_FUNCTION_CODE into an rvalue-only accessor that checks
  that the function really is BUILT_IN_NORMAL

- adds corresponding DECL_MD_FUNCTION_CODE and DECL_FE_FUNCTION_CODE
  accessors for BUILT_IN_MD and BUILT_IN_FRONTEND respectively

- adds DECL_UNCHECKED_FUNCTION_CODE for places that need to access the
  underlying field (should be low-level code only)

- adds new helpers for setting the built-in class and function code

- makes DECL_BUILT_IN_CLASS an rvalue-only accessor too, since all
  assignments should go through the new helpers

2019-08-13  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	PR middle-end/91421
	* tree-core.h (function_decl::function_code): Change type to
	unsigned int.
	* tree.h (DECL_FUNCTION_CODE): Rename old definition to...
	(DECL_UNCHECKED_FUNCTION_CODE): ...this.
	(DECL_BUILT_IN_CLASS): Make an rvalue macro only.
	(DECL_FUNCTION_CODE): New function.  Assert that the built-in class
	is BUILT_IN_NORMAL.
	(DECL_MD_FUNCTION_CODE, DECL_FE_FUNCTION_CODE): New functions.
	(set_decl_built_in_function, copy_decl_built_in_function): Likewise.
	(fndecl_built_in_p): Change the type of the "name" argument to
	unsigned int.
	* builtins.c (expand_builtin): Move DECL_FUNCTION_CODE use
	after check for DECL_BUILT_IN_CLASS.
	* cgraphclones.c (build_function_decl_skip_args): Use
	set_decl_built_in_function.
	* ipa-param-manipulation.c (ipa_modify_formal_parameters): Likewise.
	* ipa-split.c (split_function): Likewise.
	* langhooks.c (add_builtin_function_common): Likewise.
	* omp-simd-clone.c (simd_clone_create): Likewise.
	* tree-streamer-in.c (unpack_ts_function_decl_value_fields): Likewise.
	* config/darwin.c (darwin_init_cfstring_builtins): Likewise.
	(darwin_fold_builtin): Use DECL_MD_FUNCTION_CODE instead of
	DECL_FUNCTION_CODE.
	* fold-const.c (operand_equal_p): Compare DECL_UNCHECKED_FUNCTION_CODE
	instead of DECL_FUNCTION_CODE.
	* lto-streamer-out.c (hash_tree): Use DECL_UNCHECKED_FUNCTION_CODE
	instead of DECL_FUNCTION_CODE.
	* tree-streamer-out.c (pack_ts_function_decl_value_fields): Likewise.
	* print-tree.c (print_node): Use DECL_MD_FUNCTION_CODE when
	printing DECL_BUILT_IN_MD.  Handle DECL_BUILT_IN_FRONTEND.
	* config/aarch64/aarch64-builtins.c (aarch64_expand_builtin)
	(aarch64_fold_builtin, aarch64_gimple_fold_builtin): Use
	DECL_MD_FUNCTION_CODE instead of DECL_FUNCTION_CODE.
	* config/aarch64/aarch64.c (aarch64_builtin_reciprocal): Likewise.
	* config/alpha/alpha.c (alpha_expand_builtin, alpha_fold_builtin):
	(alpha_gimple_fold_builtin): Likewise.
	* config/arc/arc.c (arc_expand_builtin): Likewise.
	* config/arm/arm-builtins.c (arm_expand_builtin): Likewise.
	* config/avr/avr-c.c (avr_resolve_overloaded_builtin): Likewise.
	* config/avr/avr.c (avr_expand_builtin, avr_fold_builtin): Likewise.
	* config/bfin/bfin.c (bfin_expand_builtin): Likewise.
	* config/c6x/c6x.c (c6x_expand_builtin): Likewise.
	* config/frv/frv.c (frv_expand_builtin): Likewise.
	* config/gcn/gcn.c (gcn_expand_builtin_1): Likewise.
	(gcn_expand_builtin): Likewise.
	* config/i386/i386-builtins.c (ix86_builtin_reciprocal): Likewise.
	(fold_builtin_cpu): Likewise.
	* config/i386/i386-expand.c (ix86_expand_builtin): Likewise.
	* config/i386/i386.c (ix86_fold_builtin): Likewise.
	(ix86_gimple_fold_builtin): Likewise.
	* config/ia64/ia64.c (ia64_fold_builtin): Likewise.
	(ia64_expand_builtin): Likewise.
	* config/iq2000/iq2000.c (iq2000_expand_builtin): Likewise.
	* config/mips/mips.c (mips_expand_builtin): Likewise.
	* config/msp430/msp430.c (msp430_expand_builtin): Likewise.
	* config/nds32/nds32-intrinsic.c (nds32_expand_builtin_impl): Likewise.
	* config/nios2/nios2.c (nios2_expand_builtin): Likewise.
	* config/nvptx/nvptx.c (nvptx_expand_builtin): Likewise.
	* config/pa/pa.c (pa_expand_builtin): Likewise.
	* config/pru/pru.c (pru_expand_builtin): Likewise.
	* config/riscv/riscv-builtins.c (riscv_expand_builtin): Likewise.
	* config/rs6000/rs6000-c.c (altivec_resolve_overloaded_builtin):
	Likewise.
	* config/rs6000/rs6000-call.c (htm_expand_builtin): Likewise.
	(altivec_expand_dst_builtin, altivec_expand_builtin): Likewise.
	(rs6000_gimple_fold_builtin, rs6000_expand_builtin): Likewise.
	* config/rs6000/rs6000.c (rs6000_builtin_md_vectorized_function)
	(rs6000_builtin_reciprocal): Likewise.
	* config/rx/rx.c (rx_expand_builtin): Likewise.
	* config/s390/s390-c.c (s390_resolve_overloaded_builtin): Likewise.
	* config/s390/s390.c (s390_expand_builtin): Likewise.
	* config/sh/sh.c (sh_expand_builtin): Likewise.
	* config/sparc/sparc.c (sparc_expand_builtin): Likewise.
	(sparc_fold_builtin): Likewise.
	* config/spu/spu-c.c (spu_resolve_overloaded_builtin): Likewise.
	* config/spu/spu.c (spu_expand_builtin): Likewise.
	* config/stormy16/stormy16.c (xstormy16_expand_builtin): Likewise.
	* config/tilegx/tilegx.c (tilegx_expand_builtin): Likewise.
	* config/tilepro/tilepro.c (tilepro_expand_builtin): Likewise.
	* config/xtensa/xtensa.c (xtensa_fold_builtin): Likewise.
	(xtensa_expand_builtin): Likewise.

gcc/ada/
	PR middle-end/91421
	* gcc-interface/trans.c (gigi): Call set_decl_buillt_in_function.
	(Call_to_gnu): Use DECL_FE_FUNCTION_CODE instead of DECL_FUNCTION_CODE.

gcc/c/
	PR middle-end/91421
	* c-decl.c (merge_decls): Use copy_decl_built_in_function.

gcc/c-family/
	PR middle-end/91421
	* c-common.c (resolve_overloaded_builtin): Use
	copy_decl_built_in_function.

gcc/cp/
	PR middle-end/91421
	* decl.c (duplicate_decls):  Use copy_decl_built_in_function.
	* pt.c (declare_integer_pack): Use set_decl_built_in_function.

gcc/d/
	PR middle-end/91421
	* intrinsics.cc (maybe_set_intrinsic): Use set_decl_built_in_function.

gcc/jit/
	PR middle-end/91421
	* jit-playback.c (new_function): Use set_decl_built_in_function.

gcc/lto/
	PR middle-end/91421
	* lto-common.c (compare_tree_sccs_1): Use DECL_UNCHECKED_FUNCTION_CODE
	instead of DECL_FUNCTION_CODE.
	* lto-symtab.c (lto_symtab_merge_p): Likewise.

From-SVN: r274404

1 files changed, 63 insertions, 8 deletions

diff --git a/gcc/tree.h b/gcc/tree.h
index dd54f4d..b910c5c 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -2518,10 +2518,10 @@ extern machine_mode vector_type_mode (const_tree);
   (DECL_COMMON_CHECK (NODE)->decl_common.mode = (MODE))
 
 /* For FUNCTION_DECL, if it is built-in, this identifies which built-in
-   operation it is.  Note, however, that this field is overloaded, with
-   DECL_BUILT_IN_CLASS as the discriminant, so the latter must always be
-   checked before any access to the former.  */
-#define DECL_FUNCTION_CODE(NODE) \
+   operation it is.  This is only intended for low-level accesses;
+   normally DECL_FUNCTION_CODE, DECL_FE_FUNCTION_CODE or DECL_MD_FUNCTION
+   should be used instead.  */
+#define DECL_UNCHECKED_FUNCTION_CODE(NODE) \
   (FUNCTION_DECL_CHECK (NODE)->function_decl.function_code)
 
 /* Test if FCODE is a function code for an alloca operation.  */
@@ -3143,10 +3143,9 @@ extern vec<tree, va_gc> **decl_debug_args_insert (tree);
 #define DECL_STRUCT_FUNCTION(NODE) \
   (FUNCTION_DECL_CHECK (NODE)->function_decl.f)
 
-
 /* For a builtin function, identify which part of the compiler defined it.  */
 #define DECL_BUILT_IN_CLASS(NODE) \
-   (FUNCTION_DECL_CHECK (NODE)->function_decl.built_in_class)
+   ((built_in_class) FUNCTION_DECL_CHECK (NODE)->function_decl.built_in_class)
 
 /* In FUNCTION_DECL, a chain of ..._DECL nodes.  */
 #define DECL_ARGUMENTS(NODE) \
@@ -3885,6 +3884,61 @@ valid_vector_subparts_p (poly_uint64 subparts)
   return true;
 }
 
+/* Return the built-in function that DECL represents, given that it is known
+   to be a FUNCTION_DECL with built-in class BUILT_IN_NORMAL.  */
+inline built_in_function
+DECL_FUNCTION_CODE (const_tree decl)
+{
+  const tree_function_decl &fndecl = FUNCTION_DECL_CHECK (decl)->function_decl;
+  gcc_checking_assert (fndecl.built_in_class == BUILT_IN_NORMAL);
+  return (built_in_function) fndecl.function_code;
+}
+
+/* Return the target-specific built-in function that DECL represents,
+   given that it is known to be a FUNCTION_DECL with built-in class
+   BUILT_IN_MD.  */
+inline int
+DECL_MD_FUNCTION_CODE (const_tree decl)
+{
+  const tree_function_decl &fndecl = FUNCTION_DECL_CHECK (decl)->function_decl;
+  gcc_checking_assert (fndecl.built_in_class == BUILT_IN_MD);
+  return fndecl.function_code;
+}
+
+/* Return the frontend-specific built-in function that DECL represents,
+   given that it is known to be a FUNCTION_DECL with built-in class
+   BUILT_IN_FRONTEND.  */
+inline int
+DECL_FE_FUNCTION_CODE (const_tree decl)
+{
+  const tree_function_decl &fndecl = FUNCTION_DECL_CHECK (decl)->function_decl;
+  gcc_checking_assert (fndecl.built_in_class == BUILT_IN_FRONTEND);
+  return fndecl.function_code;
+}
+
+/* Record that FUNCTION_DECL DECL represents built-in function FCODE of
+   class FCLASS.  */
+inline void
+set_decl_built_in_function (tree decl, built_in_class fclass,
+			    unsigned int fcode)
+{
+  tree_function_decl &fndecl = FUNCTION_DECL_CHECK (decl)->function_decl;
+  fndecl.built_in_class = fclass;
+  fndecl.function_code = fcode;
+}
+
+/* Record that FUNCTION_DECL NEWDECL represents the same built-in function
+   as OLDDECL (or none, if OLDDECL doesn't represent a built-in function).  */
+inline void
+copy_decl_built_in_function (tree newdecl, const_tree olddecl)
+{
+  tree_function_decl &newfndecl = FUNCTION_DECL_CHECK (newdecl)->function_decl;
+  const tree_function_decl &oldfndecl
+    = FUNCTION_DECL_CHECK (olddecl)->function_decl;
+  newfndecl.built_in_class = oldfndecl.built_in_class;
+  newfndecl.function_code = oldfndecl.function_code;
+}
+
 /* In NON_LVALUE_EXPR and VIEW_CONVERT_EXPR, set when this node is merely a
    wrapper added to express a location_t on behalf of the node's child
    (e.g. by maybe_wrap_with_location).  */
@@ -6077,9 +6131,10 @@ fndecl_built_in_p (const_tree node, built_in_class klass)
    of class KLASS with name equal to NAME.  */
 
 inline bool
-fndecl_built_in_p (const_tree node, int name, built_in_class klass)
+fndecl_built_in_p (const_tree node, unsigned int name, built_in_class klass)
 {
-  return (fndecl_built_in_p (node, klass) && DECL_FUNCTION_CODE (node) == name);
+  return (fndecl_built_in_p (node, klass)
+	  && DECL_UNCHECKED_FUNCTION_CODE (node) == name);
 }
 
 /* Return true if a FUNCTION_DECL NODE is a GCC built-in function