d: Import dmd b8384668f, druntime e6caaab9, phobos 5ab9ad256 (v2.098.0-beta.1)

The D front-end is now itself written in D, in order to build GDC, you
will need a working GDC compiler (GCC version 9.1 or later).

GCC changes:

    - Add support for bootstrapping the D front-end.

These add the required components in order to have a D front-end written
in D itself.  Because the compiler front-end only depends on the core
runtime modules, only libdruntime is built for the bootstrap stages.

D front-end changes:

    - Import dmd v2.098.0-beta.1.

Druntime changes:

    - Import druntime v2.098.0-beta.1.

Phobos changes:

    - Import phobos v2.098.0-beta.1.

The jump from v2.076.1 to v2.098.0 covers nearly 4 years worth of
development on the D programming language and run-time libraries.

ChangeLog:

	* Makefile.def: Add bootstrap to libbacktrace, libphobos, zlib, and
	libatomic.
	* Makefile.in: Regenerate.
	* Makefile.tpl (POSTSTAGE1_HOST_EXPORTS): Fix command for GDC.
	(STAGE1_CONFIGURE_FLAGS): Add --with-libphobos-druntime-only if
	target-libphobos-bootstrap.
	(STAGE2_CONFIGURE_FLAGS): Likewise.
	* configure: Regenerate.
	* configure.ac: Add support for bootstrapping D front-end.

config/ChangeLog:

	* acx.m4 (ACX_PROG_GDC): New m4 function.

gcc/ChangeLog:

	* Makefile.in (GDC): New variable.
	(GDCFLAGS): New variable.
	* configure: Regenerate.
	* configure.ac: Add call to ACX_PROG_GDC.  Substitute GDCFLAGS.

gcc/d/ChangeLog:

	* dmd/MERGE: Merge upstream dmd b8384668f.
	* Make-lang.in (d-warn): Use strict warnings.
	(DMD_WARN_CXXFLAGS): Remove.
	(DMD_COMPILE): Remove.
	(CHECKING_DFLAGS): Define.
	(WARN_DFLAGS): Define.
	(ALL_DFLAGS): Define.
	(DCOMPILE.base): Define.
	(DCOMPILE): Define.
	(DPOSTCOMPILE): Define.
	(DLINKER): Define.
	(DLLINKER): Define.
	(D_FRONTEND_OBJS): Add new dmd front-end objects.
	(D_GENERATED_SRCS): Remove.
	(D_GENERATED_OBJS): Remove.
	(D_ALL_OBJS): Remove D_GENERATED_OBJS.
	(d21$(exeext)): Build using DLLINKER and -static-libphobos.
	(d.tags): Remove dmd/*.c and dmd/root/*.c.
	(d.mostlyclean): Remove D_GENERATED_SRCS, d/idgen$(build_exeext),
	d/impcnvgen$(build_exeext).
	(D_INCLUDES): Include $(srcdir)/d/dmd/res.
	(CFLAGS-d/id.o): Remove.
	(CFLAGS-d/impcnvtab.o): Remove.
	(d/%.o): Build using DCOMPILE and DPOSTCOMPILE.  Update dependencies
	from d/dmd/%.c to d/dmd/%.d.
	(d/idgen$(build_exeext)): Remove.
	(d/impcnvgen$(build_exeext)): Remove.
	(d/id.c): Remove.
	(d/id.h): Remove.
	(d/impcnvtab.c): Remove.
	(d/%.dmdgen.o): Remove.
	(D_SYSTEM_H): Remove.
	(d/idgen.dmdgen.o): Remove.
	(d/impcnvgen.dmdgen.o): Remove.
	* config-lang.in (boot_language): New variable.
	* d-attribs.cc: Include dmd/expression.h.
	* d-builtins.cc: Include d-frontend.h.
	(build_frontend_type): Update for new front-end interface.
	(d_eval_constant_expression): Likewise.
	(d_build_builtins_module): Likewise.
	(maybe_set_builtin_1): Likewise.
	(d_build_d_type_nodes): Likewise.
	* d-codegen.cc (d_decl_context): Likewise.
	(declaration_reference_p): Likewise.
	(declaration_type): Likewise.
	(parameter_reference_p): Likewise.
	(parameter_type): Likewise.
	(get_array_length): Likewise.
	(build_delegate_cst): Likewise.
	(build_typeof_null_value): Likewise.
	(identity_compare_p): Likewise.
	(lower_struct_comparison): Likewise.
	(build_filename_from_loc): Likewise.
	(build_assert_call): Remove LIBCALL_SWITCH_ERROR.
	(build_bounds_index_condition): Call LIBCALL_ARRAYBOUNDS_INDEXP on
	bounds error.
	(build_bounds_slice_condition): Call LIBCALL_ARRAYBOUNDS_SLICEP on
	bounds error.
	(array_bounds_check): Update for new front-end interface.
	(checkaction_trap_p): Handle CHECKACTION_context.
	(get_function_type): Update for new front-end interface.
	(d_build_call): Likewise.
	* d-compiler.cc: Remove include of dmd/scope.h.
	(Compiler::genCmain): Remove.
	(Compiler::paintAsType): Update for new front-end interface.
	(Compiler::onParseModule): Likewise.
	* d-convert.cc (convert_expr): Remove call to LIBCALL_ARRAYCAST.
	(convert_for_rvalue): Update for new front-end interface.
	(convert_for_assignment): Likewise.
	(convert_for_condition): Likewise.
	(d_array_convert): Likewise.
	* d-diagnostic.cc (error): Remove.
	(errorSupplemental): Remove.
	(warning): Remove.
	(warningSupplemental): Remove.
	(deprecation): Remove.
	(deprecationSupplemental): Remove.
	(message): Remove.
	(vtip): New.
	* d-frontend.cc (global): Remove.
	(Global::_init): Remove.
	(Global::startGagging): Remove.
	(Global::endGagging): Remove.
	(Global::increaseErrorCount): Remove.
	(Loc::Loc): Remove.
	(Loc::toChars): Remove.
	(Loc::equals): Remove.
	(isBuiltin): Update for new front-end interface.
	(eval_builtin): Likewise.
	(getTypeInfoType): Likewise.
	(inlineCopy): Remove.
	* d-incpath.cc: Include d-frontend.h.
	(add_globalpaths): Call d_gc_malloc to allocate Strings.
	(add_filepaths): Likewise.
	* d-lang.cc: Include dmd/id.h, dmd/root/file.h, d-frontend.h.  Remove
	include of dmd/mars.h, id.h.
	(entrypoint_module): Remove.
	(entrypoint_root_module): Remove.
	(deps_write_string): Update for new front-end interface.
	(deps_write): Likewise.
	(d_init_options): Call rt_init.  Remove setting global params that are
	default initialized by the front-end.
	(d_handle_option): Handle OPT_fcheckaction_, OPT_fdump_c___spec_,
	OPT_fdump_c___spec_verbose, OPT_fextern_std_, OPT_fpreview,
	OPT_revert, OPT_fsave_mixins_, and OPT_ftransition.
	(d_post_options): Propagate dip1021 and dip1000 preview flags to
	dip25, and flag_diagnostics_show_caret to printErrorContext.
	(d_add_entrypoint_module): Remove.
	(d_parse_file): Update for new front-end interface.
	(d_type_promotes_to): Likewise.
	(d_types_compatible_p): Likewise.
	* d-longdouble.cc (CTFloat::zero): Remove.
	(CTFloat::one): Remove.
	(CTFloat::minusone): Remove.
	(CTFloat::half): Remove.
	* d-system.h (POSIX): Remove.
	(realpath): Remove.
	(isalpha): Remove.
	(isalnum): Remove.
	(isdigit): Remove.
	(islower): Remove.
	(isprint): Remove.
	(isspace): Remove.
	(isupper): Remove.
	(isxdigit): Remove.
	(tolower): Remove.
	(_mkdir): Remove.
	(INT32_MAX): Remove.
	(INT32_MIN): Remove.
	(INT64_MIN): Remove.
	(UINT32_MAX): Remove.
	(UINT64_MAX): Remove.
	* d-target.cc: Include calls.h.
	(target): Remove.
	(define_float_constants): Remove initialization of snan.
	(Target::_init): Update for new front-end interface.
	(Target::isVectorTypeSupported): Likewise.
	(Target::isVectorOpSupported): Remove cases for unordered operators.
	(TargetCPP::typeMangle): Update for new front-end interface.
	(TargetCPP::parameterType): Likewise.
	(Target::systemLinkage): Likewise.
	(Target::isReturnOnStack): Likewise.
	(Target::isCalleeDestroyingArgs): Define.
	(Target::preferPassByRef): Define.
	* d-tree.h (d_add_entrypoint_module): Remove.
	* decl.cc (gcc_attribute_p): Update for new front-end interface.
	(apply_pragma_crt): Define.
	(DeclVisitor::visit(PragmaDeclaration *)): Handle pragmas
	crt_constructor and crt_destructor.
	(DeclVisitor::visit(TemplateDeclaration *)): Update for new front-end
	interface.
	(DeclVisitor::visit): Likewise.
	(DeclVisitor::finish_vtable): Likewise.
	(get_symbol_decl): Error if template has more than one nesting
	context.  Update for new front-end interface.
	(make_thunk): Update for new front-end interface.
	(get_vtable_decl): Likewise.
	* expr.cc (ExprVisitor::visit): Likewise.
	(build_return_dtor): Likewise.
	* imports.cc (ImportVisitor::visit): Likewise.
	* intrinsics.cc: Include dmd/expression.h.  Remove include of
	dmd/mangle.h.
	(maybe_set_intrinsic): Update for new front-end interface.
	* intrinsics.def (INTRINSIC_ROL): Update intrinsic signature.
	(INTRINSIC_ROR): Likewise.
	(INTRINSIC_ROR_TIARG): Likewise.
	(INTRINSIC_TOPREC): Likewise.
	(INTRINSIC_TOPRECL): Likewise.
	(INTRINSIC_TAN): Update intrinsic module and signature.
	(INTRINSIC_ISNAN): Likewise.
	(INTRINSIC_ISFINITE): Likewise.
	(INTRINSIC_COPYSIGN): Define intrinsic.
	(INTRINSIC_COPYSIGNI): Define intrinsic.
	(INTRINSIC_EXP): Update intrinsic module.
	(INTRINSIC_EXPM1): Likewise.
	(INTRINSIC_EXP2): Likewise.
	(INTRINSIC_LOG): Likewise.
	(INTRINSIC_LOG2): Likewise.
	(INTRINSIC_LOG10): Likewise.
	(INTRINSIC_POW): Likewise.
	(INTRINSIC_ROUND): Likewise.
	(INTRINSIC_FLOORF): Likewise.
	(INTRINSIC_FLOOR): Likewise.
	(INTRINSIC_FLOORL): Likewise.
	(INTRINSIC_CEILF): Likewise.
	(INTRINSIC_CEIL): Likewise.
	(INTRINSIC_CEILL): Likewise.
	(INTRINSIC_TRUNC): Likewise.
	(INTRINSIC_FMIN): Likewise.
	(INTRINSIC_FMAX): Likewise.
	(INTRINSIC_FMA): Likewise.
	(INTRINSIC_VA_ARG): Update intrinsic signature.
	(INTRINSIC_VASTART): Likewise.
	* lang.opt (fcheck=): Add alternate aliases for contract switches.
	(fcheckaction=): New option.
	(check_action): New Enum and EnumValue entries.
	(fdump-c++-spec-verbose): New option.
	(fdump-c++-spec=): New option.
	(fextern-std=): New option.
	(extern_stdcpp): New Enum and EnumValue entries
	(fpreview=): New options.
	(frevert=): New options.
	(fsave-mixins): New option.
	(ftransition=): Update options.
	* modules.cc (get_internal_fn): Replace Prot with Visibility.
	(build_internal_fn): Likewise.
	(build_dso_cdtor_fn): Likewise.
	(build_module_tree): Remove check for __entrypoint module.
	* runtime.def (P5): Define.
	(ARRAYBOUNDS_SLICEP): Define.
	(ARRAYBOUNDS_INDEXP): Define.
	(NEWTHROW): Define.
	(ADCMP2): Remove.
	(ARRAYCAST): Remove.
	(SWITCH_STRING): Remove.
	(SWITCH_USTRING): Remove.
	(SWITCH_DSTRING): Remove.
	(SWITCH_ERROR): Remove.
	* toir.cc (IRVisitor::visit): Update for new front-end interface.
	(IRVisitor::check_previous_goto): Remove checks for case and default
	statements.
	(IRVisitor::visit(SwitchStatement *)): Remove handling of string
	switch conditions.
	* typeinfo.cc: Include d-frontend.h.
	(get_typeinfo_kind): Update for new front-end interface.
	(make_frontend_typeinfo): Likewise.
	(TypeInfoVisitor::visit): Likewise.
	(builtin_typeinfo_p): Likewise.
	(get_typeinfo_decl): Likewise.
	(build_typeinfo): Likewise.
	* types.cc (valist_array_p): Likewise.
	(make_array_type): Likewise.
	(merge_aggregate_types): Likewise.
	(TypeVisitor::visit(TypeBasic *)): Likewise.
	(TypeVisitor::visit(TypeFunction *)): Likewise.
	(TypeVisitor::visit(TypeStruct *)): Update comment.
	* verstr.h: Removed.
	* d-frontend.h: New file.

gcc/po/ChangeLog:

	* EXCLUDES: Remove d/dmd sources from list.

gcc/testsuite/ChangeLog:

	* gdc.dg/Wcastresult2.d: Update test.
	* gdc.dg/asm1.d: Likewise.
	* gdc.dg/asm2.d: Likewise.
	* gdc.dg/asm3.d: Likewise.
	* gdc.dg/gdc282.d: Likewise.
	* gdc.dg/imports/gdc170.d: Likewise.
	* gdc.dg/intrinsics.d: Likewise.
	* gdc.dg/pr101672.d: Likewise.
	* gdc.dg/pr90650a.d: Likewise.
	* gdc.dg/pr90650b.d: Likewise.
	* gdc.dg/pr94777a.d: Likewise.
	* gdc.dg/pr95250.d: Likewise.
	* gdc.dg/pr96869.d: Likewise.
	* gdc.dg/pr98277.d: Likewise.
	* gdc.dg/pr98457.d: Likewise.
	* gdc.dg/simd1.d: Likewise.
	* gdc.dg/simd2a.d: Likewise.
	* gdc.dg/simd2b.d: Likewise.
	* gdc.dg/simd2c.d: Likewise.
	* gdc.dg/simd2d.d: Likewise.
	* gdc.dg/simd2e.d: Likewise.
	* gdc.dg/simd2f.d: Likewise.
	* gdc.dg/simd2g.d: Likewise.
	* gdc.dg/simd2h.d: Likewise.
	* gdc.dg/simd2i.d: Likewise.
	* gdc.dg/simd2j.d: Likewise.
	* gdc.dg/simd7951.d: Likewise.
	* gdc.dg/torture/gdc309.d: Likewise.
	* gdc.dg/torture/pr94424.d: Likewise.
	* gdc.dg/torture/pr94777b.d: Likewise.
	* lib/gdc-utils.exp (gdc-convert-args): Handle new compiler options.
	(gdc-convert-test): Handle CXXFLAGS, EXTRA_OBJC_SOURCES, and ARG_SETS
	test directives.
	(gdc-do-test): Only import modules in the test run directory.
	* gdc.dg/pr94777c.d: New test.
	* gdc.dg/pr96156b.d: New test.
	* gdc.dg/pr96157c.d: New test.
	* gdc.dg/simd_ctfe.d: New test.
	* gdc.dg/torture/simd17344.d: New test.
	* gdc.dg/torture/simd20052.d: New test.
	* gdc.dg/torture/simd6.d: New test.
	* gdc.dg/torture/simd7.d: New test.

libphobos/ChangeLog:

	* libdruntime/MERGE: Merge upstream druntime e6caaab9.
	* libdruntime/Makefile.am (D_EXTRA_FLAGS): Build libdruntime with
	-fpreview=dip1000, -fpreview=fieldwise, and -fpreview=dtorfields.
	(ALL_DRUNTIME_SOURCES): Add DRUNTIME_DSOURCES_STDCXX.
	(DRUNTIME_DSOURCES): Update list of C binding modules.
	(DRUNTIME_DSOURCES_STDCXX): Likewise.
	(DRUNTIME_DSOURCES_LINUX): Likewise.
	(DRUNTIME_DSOURCES_OPENBSD): Likewise.
	(DRUNTIME_DISOURCES): Remove __entrypoint.di.
	* libdruntime/Makefile.in: Regenerated.
	* libdruntime/__entrypoint.di: Removed.
	* libdruntime/gcc/deh.d (_d_isbaseof): Update signature.
	(_d_createTrace): Likewise.
	(__gdc_begin_catch): Remove reference to the exception.
	(_d_throw): Increment reference count of thrown object before unwind.
	(__gdc_personality): Chain exceptions with  Throwable.chainTogether.
	* libdruntime/gcc/emutls.d: Update imports.
	* libdruntime/gcc/sections/elf.d: Update imports.
	(DSO.moduleGroup): Update signature.
	* libdruntime/gcc/sections/macho.d: Update imports.
	(DSO.moduleGroup): Update signature.
	* libdruntime/gcc/sections/pecoff.d: Update imports.
	(DSO.moduleGroup): Update signature.
	* src/MERGE: Merge upstream phobos 5ab9ad256.
	* src/Makefile.am (D_EXTRA_DFLAGS): Add -fpreview=dip1000 and
	-fpreview=dtorfields flags.
	(PHOBOS_DSOURCES): Update list of std modules.
	* src/Makefile.in: Regenerate.
	* testsuite/lib/libphobos.exp (libphobos-dg-test): Handle assembly
	compile types.
	(dg-test): Override.
	(additional_prunes): Define.
	(libphobos-dg-prune): Filter any additional_prunes set by tests.
	* testsuite/libphobos.aa/test_aa.d: Update test.
	* testsuite/libphobos.druntime/druntime.exp (version_flags): Add
	-fversion=CoreUnittest.
	* testsuite/libphobos.druntime_shared/druntime_shared.exp
	(version_flags): Add -fversion=CoreUnittest -fversion=Shared.
	* testsuite/libphobos.exceptions/unknown_gc.d: Update test.
	* testsuite/libphobos.hash/test_hash.d: Update test.
	* testsuite/libphobos.phobos/phobos.exp (version_flags): Add
	-fversion=StdUnittest
	* testsuite/libphobos.phobos_shared/phobos_shared.exp (version_flags):
	Likewise.
	* testsuite/libphobos.shared/host.c: Update test.
	* testsuite/libphobos.shared/load.d: Update test.
	* testsuite/libphobos.shared/load_13414.d: Update test.
	* testsuite/libphobos.thread/fiber_guard_page.d: Update test.
	* testsuite/libphobos.thread/tlsgc_sections.d: Update test.
	* testsuite/testsuite_flags.in: Add -fpreview=dip1000 to --gdcflags.
	* testsuite/libphobos.shared/link_mod_collision.d: Removed.
	* testsuite/libphobos.shared/load_mod_collision.d: Removed.
	* testsuite/libphobos.betterc/betterc.exp: New test.
	* testsuite/libphobos.config/config.exp: New test.
	* testsuite/libphobos.gc/gc.exp: New test.
	* testsuite/libphobos.imports/imports.exp: New test.
	* testsuite/libphobos.lifetime/lifetime.exp: New test.
	* testsuite/libphobos.unittest/unittest.exp: New test.

1 files changed, 375 insertions, 0 deletions

diff --git a/gcc/d/dmd/root/rmem.d b/gcc/d/dmd/root/rmem.d
new file mode 100644
index 0000000..198f3d0
--- /dev/null
+++ b/gcc/d/dmd/root/rmem.d
@@ -0,0 +1,375 @@
+/**
+ * Allocate memory using `malloc` or the GC depending on the configuration.
+ *
+ * Copyright: Copyright (C) 1999-2021 by The D Language Foundation, All Rights Reserved
+ * Authors:   Walter Bright, http://www.digitalmars.com
+ * License:   $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost License 1.0)
+ * Source:    $(LINK2 https://github.com/dlang/dmd/blob/master/src/dmd/root/rmem.d, root/_rmem.d)
+ * Documentation:  https://dlang.org/phobos/dmd_root_rmem.html
+ * Coverage:    https://codecov.io/gh/dlang/dmd/src/master/src/dmd/root/rmem.d
+ */
+
+module dmd.root.rmem;
+
+import core.exception : onOutOfMemoryError;
+import core.stdc.stdio;
+import core.stdc.stdlib;
+import core.stdc.string;
+
+import core.memory : GC;
+
+extern (C++) struct Mem
+{
+    static char* xstrdup(const(char)* s) nothrow
+    {
+        if (isGCEnabled)
+            return s ? s[0 .. strlen(s) + 1].dup.ptr : null;
+
+        return s ? cast(char*)check(.strdup(s)) : null;
+    }
+
+    static void xfree(void* p) pure nothrow
+    {
+        if (isGCEnabled)
+            return GC.free(p);
+
+        pureFree(p);
+    }
+
+    static void* xmalloc(size_t size) pure nothrow
+    {
+        if (isGCEnabled)
+            return size ? GC.malloc(size) : null;
+
+        return size ? check(pureMalloc(size)) : null;
+    }
+
+    static void* xmalloc_noscan(size_t size) pure nothrow
+    {
+        if (isGCEnabled)
+            return size ? GC.malloc(size, GC.BlkAttr.NO_SCAN) : null;
+
+        return size ? check(pureMalloc(size)) : null;
+    }
+
+    static void* xcalloc(size_t size, size_t n) pure nothrow
+    {
+        if (isGCEnabled)
+            return size * n ? GC.calloc(size * n) : null;
+
+        return (size && n) ? check(pureCalloc(size, n)) : null;
+    }
+
+    static void* xcalloc_noscan(size_t size, size_t n) pure nothrow
+    {
+        if (isGCEnabled)
+            return size * n ? GC.calloc(size * n, GC.BlkAttr.NO_SCAN) : null;
+
+        return (size && n) ? check(pureCalloc(size, n)) : null;
+    }
+
+    static void* xrealloc(void* p, size_t size) pure nothrow
+    {
+        if (isGCEnabled)
+            return GC.realloc(p, size);
+
+        if (!size)
+        {
+            pureFree(p);
+            return null;
+        }
+
+        return check(pureRealloc(p, size));
+    }
+
+    static void* xrealloc_noscan(void* p, size_t size) pure nothrow
+    {
+        if (isGCEnabled)
+            return GC.realloc(p, size, GC.BlkAttr.NO_SCAN);
+
+        if (!size)
+        {
+            pureFree(p);
+            return null;
+        }
+
+        return check(pureRealloc(p, size));
+    }
+
+    static void* error() pure nothrow @nogc @safe
+    {
+        onOutOfMemoryError();
+        assert(0);
+    }
+
+    /**
+     * Check p for null. If it is, issue out of memory error
+     * and exit program.
+     * Params:
+     *  p = pointer to check for null
+     * Returns:
+     *  p if not null
+     */
+    static void* check(void* p) pure nothrow @nogc
+    {
+        return p ? p : error();
+    }
+
+    __gshared bool _isGCEnabled = true;
+
+    // fake purity by making global variable immutable (_isGCEnabled only modified before startup)
+    enum _pIsGCEnabled = cast(immutable bool*) &_isGCEnabled;
+
+    static bool isGCEnabled() pure nothrow @nogc @safe
+    {
+        return *_pIsGCEnabled;
+    }
+
+    static void disableGC() nothrow @nogc
+    {
+        _isGCEnabled = false;
+    }
+
+    static void addRange(const(void)* p, size_t size) nothrow @nogc
+    {
+        if (isGCEnabled)
+            GC.addRange(p, size);
+    }
+
+    static void removeRange(const(void)* p) nothrow @nogc
+    {
+        if (isGCEnabled)
+            GC.removeRange(p);
+    }
+}
+
+extern (C++) const __gshared Mem mem;
+
+enum CHUNK_SIZE = (256 * 4096 - 64);
+
+__gshared size_t heapleft = 0;
+__gshared void* heapp;
+
+extern (D) void* allocmemoryNoFree(size_t m_size) nothrow @nogc
+{
+    // 16 byte alignment is better (and sometimes needed) for doubles
+    m_size = (m_size + 15) & ~15;
+
+    // The layout of the code is selected so the most common case is straight through
+    if (m_size <= heapleft)
+    {
+    L1:
+        heapleft -= m_size;
+        auto p = heapp;
+        heapp = cast(void*)(cast(char*)heapp + m_size);
+        return p;
+    }
+
+    if (m_size > CHUNK_SIZE)
+    {
+        return Mem.check(malloc(m_size));
+    }
+
+    heapleft = CHUNK_SIZE;
+    heapp = Mem.check(malloc(CHUNK_SIZE));
+    goto L1;
+}
+
+extern (D) void* allocmemory(size_t m_size) nothrow
+{
+    if (mem.isGCEnabled)
+        return GC.malloc(m_size);
+
+    return allocmemoryNoFree(m_size);
+}
+
+version (DigitalMars)
+{
+    enum OVERRIDE_MEMALLOC = true;
+}
+else version (LDC)
+{
+    // Memory allocation functions gained weak linkage when the @weak attribute was introduced.
+    import ldc.attributes;
+    enum OVERRIDE_MEMALLOC = is(typeof(ldc.attributes.weak));
+}
+else version (GNU)
+{
+    version (IN_GCC)
+        enum OVERRIDE_MEMALLOC = false;
+    else
+        enum OVERRIDE_MEMALLOC = true;
+}
+else
+{
+    enum OVERRIDE_MEMALLOC = false;
+}
+
+static if (OVERRIDE_MEMALLOC)
+{
+    // Override the host druntime allocation functions in order to use the bump-
+    // pointer allocation scheme (`allocmemoryNoFree()` above) if the GC is disabled.
+    // That scheme is faster and comes with less memory overhead than using a
+    // disabled GC alone.
+
+    extern (C) void* _d_allocmemory(size_t m_size) nothrow
+    {
+        return allocmemory(m_size);
+    }
+
+    private void* allocClass(const ClassInfo ci) nothrow pure
+    {
+        alias BlkAttr = GC.BlkAttr;
+
+        assert(!(ci.m_flags & TypeInfo_Class.ClassFlags.isCOMclass));
+
+        BlkAttr attr = BlkAttr.NONE;
+        if (ci.m_flags & TypeInfo_Class.ClassFlags.hasDtor
+            && !(ci.m_flags & TypeInfo_Class.ClassFlags.isCPPclass))
+            attr |= BlkAttr.FINALIZE;
+        if (ci.m_flags & TypeInfo_Class.ClassFlags.noPointers)
+            attr |= BlkAttr.NO_SCAN;
+        return GC.malloc(ci.initializer.length, attr, ci);
+    }
+
+    extern (C) void* _d_newitemU(const TypeInfo ti) nothrow;
+
+    extern (C) Object _d_newclass(const ClassInfo ci) nothrow
+    {
+        const initializer = ci.initializer;
+
+        auto p = mem.isGCEnabled ? allocClass(ci) : allocmemoryNoFree(initializer.length);
+        memcpy(p, initializer.ptr, initializer.length);
+        return cast(Object) p;
+    }
+
+    version (LDC)
+    {
+        extern (C) Object _d_allocclass(const ClassInfo ci) nothrow
+        {
+            if (mem.isGCEnabled)
+                return cast(Object) allocClass(ci);
+
+            return cast(Object) allocmemoryNoFree(ci.initializer.length);
+        }
+    }
+
+    extern (C) void* _d_newitemT(TypeInfo ti) nothrow
+    {
+        auto p = mem.isGCEnabled ? _d_newitemU(ti) : allocmemoryNoFree(ti.tsize);
+        memset(p, 0, ti.tsize);
+        return p;
+    }
+
+    extern (C) void* _d_newitemiT(TypeInfo ti) nothrow
+    {
+        auto p = mem.isGCEnabled ? _d_newitemU(ti) : allocmemoryNoFree(ti.tsize);
+        const initializer = ti.initializer;
+        memcpy(p, initializer.ptr, initializer.length);
+        return p;
+    }
+
+    // TypeInfo.initializer for compilers older than 2.070
+    static if(!__traits(hasMember, TypeInfo, "initializer"))
+    private const(void[]) initializer(T : TypeInfo)(const T t)
+    nothrow pure @safe @nogc
+    {
+        return t.init;
+    }
+}
+
+extern (C) pure @nogc nothrow
+{
+    /**
+     * Pure variants of C's memory allocation functions `malloc`, `calloc`, and
+     * `realloc` and deallocation function `free`.
+     *
+     * UNIX 98 requires that errno be set to ENOMEM upon failure.
+     * https://linux.die.net/man/3/malloc
+     * However, this is irrelevant for DMD's purposes, and best practice
+     * protocol for using errno is to treat it as an `out` parameter, and not
+     * something with state that can be relied on across function calls.
+     * So, we'll ignore it.
+     *
+     * See_Also:
+     *     $(LINK2 https://dlang.org/spec/function.html#pure-functions, D's rules for purity),
+     *     which allow for memory allocation under specific circumstances.
+     */
+    pragma(mangle, "malloc") void* pureMalloc(size_t size) @trusted;
+
+    /// ditto
+    pragma(mangle, "calloc") void* pureCalloc(size_t nmemb, size_t size) @trusted;
+
+    /// ditto
+    pragma(mangle, "realloc") void* pureRealloc(void* ptr, size_t size) @system;
+
+    /// ditto
+    pragma(mangle, "free") void pureFree(void* ptr) @system;
+
+}
+
+/**
+Makes a null-terminated copy of the given string on newly allocated memory.
+The null-terminator won't be part of the returned string slice. It will be
+at position `n` where `n` is the length of the input string.
+
+Params:
+    s = string to copy
+
+Returns: A null-terminated copy of the input array.
+*/
+extern (D) char[] xarraydup(const(char)[] s) pure nothrow
+{
+    if (!s)
+        return null;
+
+    auto p = cast(char*)mem.xmalloc_noscan(s.length + 1);
+    char[] a = p[0 .. s.length];
+    a[] = s[0 .. s.length];
+    p[s.length] = 0;    // preserve 0 terminator semantics
+    return a;
+}
+
+///
+pure nothrow unittest
+{
+    auto s1 = "foo";
+    auto s2 = s1.xarraydup;
+    s2[0] = 'b';
+    assert(s1 == "foo");
+    assert(s2 == "boo");
+    assert(*(s2.ptr + s2.length) == '\0');
+    string sEmpty;
+    assert(sEmpty.xarraydup is null);
+}
+
+/**
+Makes a copy of the given array on newly allocated memory.
+
+Params:
+    s = array to copy
+
+Returns: A copy of the input array.
+*/
+extern (D) T[] arraydup(T)(const scope T[] s) pure nothrow
+{
+    if (!s)
+        return null;
+
+    const dim = s.length;
+    auto p = (cast(T*)mem.xmalloc(T.sizeof * dim))[0 .. dim];
+    p[] = s;
+    return p;
+}
+
+///
+pure nothrow unittest
+{
+    auto s1 = [0, 1, 2];
+    auto s2 = s1.arraydup;
+    s2[0] = 4;
+    assert(s1 == [0, 1, 2]);
+    assert(s2 == [4, 1, 2]);
+    string sEmpty;
+    assert(sEmpty.arraydup is null);
+}