delete all stage1 c++ code not directly related to compiling stage2

Deleted 16,000+ lines of c++ code, including:
 * an implementation of blake hashing
 * the cache hash system
 * compiler.cpp
 * all the linking code, and everything having to do with building
   glibc, musl, and mingw-w64
 * much of the stage1 compiler internals got slimmed down since it
   now assumes it is always outputting an object file.

More stuff:
 * stage1 is now built with a different strategy: we have a tiny
   zig0.cpp which is a slimmed down version of what stage1 main.cpp used
   to be. Its only purpose is to build stage2 zig code into an object
   file, which is then linked by the host build system (cmake) into
   stage1. zig0.cpp uses the same C API that stage2 now has access to,
   so that stage2 zig code can call into stage1 c++ code.
   - stage1.h is
   - stage2.h is
   - stage1.zig is the main entry point for the Zig/C++
     hybrid compiler. It has the functions exported from Zig, called
     in C++, and bindings for the functions exported from C++, called
     from Zig.
 * removed the memory profiling instrumentation from stage1.
   Abandon ship!
 * Re-added the sections to the README about how to build stage2 and
   stage3.
 * stage2 now knows as a comptime boolean whether it is being compiled
   as part of stage1 or as stage2.
   - TODO use this flag to call into stage1 for compiling zig code.
 * introduce -fdll-export-fns and -fno-dll-export-fns and clarify
   its relationship to link_mode (static/dynamic)
 * implement depending on LLVM to detect native target cpu features when
   LLVM extensions are enabled and zig lacks CPU feature detection for
   that target architecture.
 * C importing is broken, will need some stage2 support to function
   again.

1 files changed, 5 insertions, 176 deletions

diff --git a/src/ir.cpp b/src/ir.cpp
index 6cb5d8bc2d..50076f9a86 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -22570,38 +22570,12 @@ static IrInstGen *ir_analyze_container_field_ptr(IrAnalyze *ira, Buf *field_name
 }
 
 static void add_link_lib_symbol(IrAnalyze *ira, Buf *lib_name, Buf *symbol_name, AstNode *source_node) {
-    bool is_libc = target_is_libc_lib_name(ira->codegen->zig_target, buf_ptr(lib_name));
-    if (is_libc && ira->codegen->libc_link_lib == nullptr && !ira->codegen->reported_bad_link_libc_error) {
-        ir_add_error_node(ira, source_node,
-            buf_sprintf("dependency on library c must be explicitly specified in the build command"));
-        ira->codegen->reported_bad_link_libc_error = true;
-    }
-
-    LinkLib *link_lib = add_link_lib(ira->codegen, lib_name);
-    for (size_t i = 0; i < link_lib->symbols.length; i += 1) {
-        Buf *existing_symbol_name = link_lib->symbols.at(i);
-        if (buf_eql_buf(existing_symbol_name, symbol_name)) {
-            return;
-        }
-    }
-
-    if (!is_libc && !target_is_wasm(ira->codegen->zig_target) && !ira->codegen->have_pic && !ira->codegen->reported_bad_link_libc_error) {
-        ErrorMsg *msg = ir_add_error_node(ira, source_node,
-            buf_sprintf("dependency on dynamic library '%s' requires enabling Position Independent Code",
-                buf_ptr(lib_name)));
-        add_error_note(ira->codegen, msg, source_node,
-                buf_sprintf("fixed by `--library %s` or `-fPIC`", buf_ptr(lib_name)));
+    const char *msg = stage2_add_link_lib(&ira->codegen->stage1, buf_ptr(lib_name), buf_len(lib_name),
+            buf_ptr(symbol_name), buf_len(symbol_name));
+    if (msg != nullptr) {
+        ir_add_error_node(ira, source_node, buf_create_from_str(msg));
         ira->codegen->reported_bad_link_libc_error = true;
     }
-
-    for (size_t i = 0; i < ira->codegen->forbidden_libs.length; i += 1) {
-        Buf *forbidden_lib_name = ira->codegen->forbidden_libs.at(i);
-        if (buf_eql_buf(lib_name, forbidden_lib_name)) {
-            ir_add_error_node(ira, source_node,
-                buf_sprintf("linking against forbidden library '%s'", buf_ptr(symbol_name)));
-        }
-    }
-    link_lib->symbols.append(symbol_name);
 }
 
 static IrInstGen *ir_error_dependency_loop(IrAnalyze *ira, IrInst* source_instr) {
@@ -26355,13 +26329,6 @@ static IrInstGen *ir_analyze_instruction_type_name(IrAnalyze *ira, IrInstSrcType
     return result;
 }
 
-static void ir_cimport_cache_paths(Buf *cache_dir, Buf *tmp_c_file_digest, Buf *out_zig_dir, Buf *out_zig_path) {
-    buf_resize(out_zig_dir, 0);
-    buf_resize(out_zig_path, 0);
-    buf_appendf(out_zig_dir, "%s" OS_SEP "o" OS_SEP "%s",
-            buf_ptr(cache_dir), buf_ptr(tmp_c_file_digest));
-    buf_appendf(out_zig_path, "%s" OS_SEP "cimport.zig", buf_ptr(out_zig_dir));
-}
 static IrInstGen *ir_analyze_instruction_c_import(IrAnalyze *ira, IrInstSrcCImport *instruction) {
     Error err;
     AstNode *node = instruction->base.base.source_node;
@@ -26393,145 +26360,7 @@ static IrInstGen *ir_analyze_instruction_c_import(IrAnalyze *ira, IrInstSrcCImpo
     cimport_pkg->package_table.put(buf_create_from_str("std"), ira->codegen->std_package);
     buf_init_from_buf(&cimport_pkg->pkg_path, namespace_name);
 
-    CacheHash *cache_hash;
-    if ((err = create_c_object_cache(ira->codegen, &cache_hash, false))) {
-        ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to create cache: %s", err_str(err)));
-        return ira->codegen->invalid_inst_gen;
-    }
-    cache_buf(cache_hash, &cimport_scope->buf);
-
-    // Set this because we're not adding any files before checking for a hit.
-    cache_hash->force_check_manifest = true;
-
-    Buf tmp_c_file_digest = BUF_INIT;
-    buf_resize(&tmp_c_file_digest, 0);
-    if ((err = cache_hit(cache_hash, &tmp_c_file_digest))) {
-        if (err != ErrorInvalidFormat) {
-            ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to check cache: %s", err_str(err)));
-            return ira->codegen->invalid_inst_gen;
-        }
-    }
-    ira->codegen->caches_to_release.append(cache_hash);
-
-    Buf *out_zig_dir = buf_alloc();
-    Buf *out_zig_path = buf_alloc();
-    if (buf_len(&tmp_c_file_digest) == 0 || cache_hash->files.length == 0) {
-        // Cache Miss
-        Buf *tmp_c_file_dir = buf_sprintf("%s" OS_SEP "o" OS_SEP "%s",
-                buf_ptr(ira->codegen->cache_dir), buf_ptr(&cache_hash->b64_digest));
-        Buf *resolve_paths[] = {
-            tmp_c_file_dir,
-            buf_create_from_str("cimport.h"),
-        };
-        Buf tmp_c_file_path = os_path_resolve(resolve_paths, 2);
-
-        if ((err = os_make_path(tmp_c_file_dir))) {
-            ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to make dir: %s", err_str(err)));
-            return ira->codegen->invalid_inst_gen;
-        }
-
-        if ((err = os_write_file(&tmp_c_file_path, &cimport_scope->buf))) {
-            ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to write .h file: %s", err_str(err)));
-            return ira->codegen->invalid_inst_gen;
-        }
-        if (ira->codegen->verbose_cimport) {
-            fprintf(stderr, "@cImport source: %s\n", buf_ptr(&tmp_c_file_path));
-        }
-
-        Buf *tmp_dep_file = buf_sprintf("%s.d", buf_ptr(&tmp_c_file_path));
-
-        ZigList<const char *> clang_argv = {0};
-
-        add_cc_args(ira->codegen, clang_argv, buf_ptr(tmp_dep_file), true, FileExtC);
-
-        clang_argv.append(buf_ptr(&tmp_c_file_path));
-
-        if (ira->codegen->verbose_cc) {
-            fprintf(stderr, "clang");
-            for (size_t i = 0; i < clang_argv.length; i += 1) {
-                fprintf(stderr, " %s", clang_argv.at(i));
-            }
-            fprintf(stderr, "\n");
-        }
-
-        clang_argv.append(nullptr); // to make the [start...end] argument work
-
-        Stage2ErrorMsg *errors_ptr;
-        size_t errors_len;
-        Stage2Ast *ast;
-
-        const char *resources_path = buf_ptr(ira->codegen->zig_c_headers_dir);
-
-        if ((err = stage2_translate_c(&ast, &errors_ptr, &errors_len,
-                    &clang_argv.at(0), &clang_argv.last(), resources_path)))
-        {
-            if (err != ErrorCCompileErrors) {
-                ir_add_error_node(ira, node, buf_sprintf("C import failed: %s", err_str(err)));
-                return ira->codegen->invalid_inst_gen;
-            }
-
-            ErrorMsg *parent_err_msg = ir_add_error_node(ira, node, buf_sprintf("C import failed"));
-            if (ira->codegen->libc_link_lib == nullptr) {
-                add_error_note(ira->codegen, parent_err_msg, node,
-                    buf_sprintf("libc headers not available; compilation does not link against libc"));
-            }
-            for (size_t i = 0; i < errors_len; i += 1) {
-                Stage2ErrorMsg *clang_err = &errors_ptr[i];
-                // Clang can emit "too many errors, stopping now", in which case `source` and `filename_ptr` are null
-                if (clang_err->source && clang_err->filename_ptr) {
-                    ErrorMsg *err_msg = err_msg_create_with_offset(
-                        clang_err->filename_ptr ?
-                            buf_create_from_mem(clang_err->filename_ptr, clang_err->filename_len) : buf_alloc(),
-                        clang_err->line, clang_err->column, clang_err->offset, clang_err->source,
-                        buf_create_from_mem(clang_err->msg_ptr, clang_err->msg_len));
-                    err_msg_add_note(parent_err_msg, err_msg);
-                }
-            }
-
-            return ira->codegen->invalid_inst_gen;
-        }
-        if (ira->codegen->verbose_cimport) {
-            fprintf(stderr, "@cImport .d file: %s\n", buf_ptr(tmp_dep_file));
-        }
-
-        if ((err = cache_add_dep_file(cache_hash, tmp_dep_file, false))) {
-            ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to parse .d file: %s", err_str(err)));
-            return ira->codegen->invalid_inst_gen;
-        }
-        if ((err = cache_final(cache_hash, &tmp_c_file_digest))) {
-            ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to finalize cache: %s", err_str(err)));
-            return ira->codegen->invalid_inst_gen;
-        }
-
-        ir_cimport_cache_paths(ira->codegen->cache_dir, &tmp_c_file_digest, out_zig_dir, out_zig_path);
-        if ((err = os_make_path(out_zig_dir))) {
-            ir_add_error_node(ira, node, buf_sprintf("C import failed: unable to make output dir: %s", err_str(err)));
-            return ira->codegen->invalid_inst_gen;
-        }
-        FILE *out_file = fopen(buf_ptr(out_zig_path), "wb");
-        if (out_file == nullptr) {
-            ir_add_error_node(ira, node,
-                    buf_sprintf("C import failed: unable to open output file: %s", strerror(errno)));
-            return ira->codegen->invalid_inst_gen;
-        }
-        stage2_render_ast(ast, out_file);
-        if (fclose(out_file) != 0) {
-            ir_add_error_node(ira, node,
-                    buf_sprintf("C import failed: unable to write to output file: %s", strerror(errno)));
-            return ira->codegen->invalid_inst_gen;
-        }
-
-        if (ira->codegen->verbose_cimport) {
-            fprintf(stderr, "@cImport output: %s\n", buf_ptr(out_zig_path));
-        }
-
-    } else {
-        // Cache Hit
-        ir_cimport_cache_paths(ira->codegen->cache_dir, &tmp_c_file_digest, out_zig_dir, out_zig_path);
-        if (ira->codegen->verbose_cimport) {
-            fprintf(stderr, "@cImport cache hit: %s\n", buf_ptr(out_zig_path));
-        }
-    }
+    Buf *out_zig_path = buf_create_from_str(stage2_cimport(&ira->codegen->stage1));
 
     Buf *import_code = buf_alloc();
     if ((err = file_fetch(ira->codegen, out_zig_path, import_code))) {