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