add -femit-llvm-bc CLI option and implement it

 * Added doc comments for `std.Target.ObjectFormat` enum
 * `std.Target.oFileExt` is removed because it is incorrect for Plan-9
   targets. Instead, use `std.Target.ObjectFormat.fileExt` and pass a
   CPU architecture.
 * Added `Compilation.Directory.joinZ` for when a null byte is desired.
 * Improvements to `Compilation.create` logic for computing `use_llvm`
   and reporting errors in contradictory flags. `-femit-llvm-ir` and
   `-femit-llvm-bc` will now imply `-fLLVM`.
 * Fix compilation when passing `.bc` files on the command line.
 * Improvements to the stage2 LLVM backend:
   - cleaned up error messages and error reporting. Properly bubble up
     some errors rather than dumping to stderr; others turn into panics.
   - properly call ZigLLVMCreateTargetMachine and
     ZigLLVMTargetMachineEmitToFile and implement calculation of the
     respective parameters (cpu features, code model, abi name, lto,
     tsan, etc).
   - LLVM module verification only runs in debug builds of the compiler
   - use LLVMDumpModule rather than printToString because in the case
     that we incorrectly pass a null pointer to LLVM it may crash during
     dumping the module and having it partially printed is helpful in
     this case.
   - support -femit-asm, -fno-emit-bin, -femit-llvm-ir, -femit-llvm-bc
   - Support LLVM backend when used with Mach-O and WASM linkers.

1 files changed, 31 insertions, 7 deletions

diff --git a/src/main.zig b/src/main.zig
index 9a51eba5f6..db7fc17df0 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -301,6 +301,8 @@ const usage_build_generic =
     \\  -fno-emit-asm             (default) Do not output .s (assembly code)
     \\  -femit-llvm-ir[=path]     Produce a .ll file with LLVM IR (requires LLVM extensions)
     \\  -fno-emit-llvm-ir         (default) Do not produce a .ll file with LLVM IR
+    \\  -femit-llvm-bc[=path]     Produce a LLVM module as a .bc file (requires LLVM extensions)
+    \\  -fno-emit-llvm-bc         (default) Do not produce a LLVM module as a .bc file
     \\  -femit-h[=path]           Generate a C header file (.h)
     \\  -fno-emit-h               (default) Do not generate a C header file (.h)
     \\  -femit-docs[=path]        Create a docs/ dir with html documentation
@@ -359,7 +361,7 @@ const usage_build_generic =
     \\  --single-threaded         Code assumes it is only used single-threaded
     \\  -ofmt=[mode]              Override target object format
     \\    elf                     Executable and Linking Format
-    \\    c                       Compile to C source code
+    \\    c                       C source code
     \\    wasm                    WebAssembly
     \\    coff                    Common Object File Format (Windows)
     \\    macho                   macOS relocatables
@@ -551,6 +553,7 @@ fn buildOutputType(
     var emit_bin: EmitBin = .yes_default_path;
     var emit_asm: Emit = .no;
     var emit_llvm_ir: Emit = .no;
+    var emit_llvm_bc: Emit = .no;
     var emit_docs: Emit = .no;
     var emit_analysis: Emit = .no;
     var target_arch_os_abi: []const u8 = "native";
@@ -1010,6 +1013,12 @@ fn buildOutputType(
                         emit_llvm_ir = .{ .yes = arg["-femit-llvm-ir=".len..] };
                     } else if (mem.eql(u8, arg, "-fno-emit-llvm-ir")) {
                         emit_llvm_ir = .no;
+                    } else if (mem.eql(u8, arg, "-femit-llvm-bc")) {
+                        emit_llvm_bc = .yes_default_path;
+                    } else if (mem.startsWith(u8, arg, "-femit-llvm-bc=")) {
+                        emit_llvm_bc = .{ .yes = arg["-femit-llvm-bc=".len..] };
+                    } else if (mem.eql(u8, arg, "-fno-emit-llvm-bc")) {
+                        emit_llvm_bc = .no;
                     } else if (mem.eql(u8, arg, "-femit-docs")) {
                         emit_docs = .yes_default_path;
                     } else if (mem.startsWith(u8, arg, "-femit-docs=")) {
@@ -1815,10 +1824,10 @@ fn buildOutputType(
     var emit_h_resolved = emit_h.resolve(default_h_basename) catch |err| {
         switch (emit_h) {
             .yes => {
-                fatal("unable to open directory from argument 'femit-h', '{s}': {s}", .{ emit_h.yes, @errorName(err) });
+                fatal("unable to open directory from argument '-femit-h', '{s}': {s}", .{ emit_h.yes, @errorName(err) });
             },
             .yes_default_path => {
-                fatal("unable to open directory from arguments 'name' or 'soname', '{s}': {s}", .{ default_h_basename, @errorName(err) });
+                fatal("unable to open directory from arguments '--name' or '-fsoname', '{s}': {s}", .{ default_h_basename, @errorName(err) });
             },
             .no => unreachable,
         }
@@ -1829,10 +1838,10 @@ fn buildOutputType(
     var emit_asm_resolved = emit_asm.resolve(default_asm_basename) catch |err| {
         switch (emit_asm) {
             .yes => {
-                fatal("unable to open directory from argument 'femit-asm', '{s}': {s}", .{ emit_asm.yes, @errorName(err) });
+                fatal("unable to open directory from argument '-femit-asm', '{s}': {s}", .{ emit_asm.yes, @errorName(err) });
             },
             .yes_default_path => {
-                fatal("unable to open directory from arguments 'name' or 'soname', '{s}': {s}", .{ default_asm_basename, @errorName(err) });
+                fatal("unable to open directory from arguments '--name' or '-fsoname', '{s}': {s}", .{ default_asm_basename, @errorName(err) });
             },
             .no => unreachable,
         }
@@ -1843,16 +1852,30 @@ fn buildOutputType(
     var emit_llvm_ir_resolved = emit_llvm_ir.resolve(default_llvm_ir_basename) catch |err| {
         switch (emit_llvm_ir) {
             .yes => {
-                fatal("unable to open directory from argument 'femit-llvm-ir', '{s}': {s}", .{ emit_llvm_ir.yes, @errorName(err) });
+                fatal("unable to open directory from argument '-femit-llvm-ir', '{s}': {s}", .{ emit_llvm_ir.yes, @errorName(err) });
             },
             .yes_default_path => {
-                fatal("unable to open directory from arguments 'name' or 'soname', '{s}': {s}", .{ default_llvm_ir_basename, @errorName(err) });
+                fatal("unable to open directory from arguments '--name' or '-fsoname', '{s}': {s}", .{ default_llvm_ir_basename, @errorName(err) });
             },
             .no => unreachable,
         }
     };
     defer emit_llvm_ir_resolved.deinit();
 
+    const default_llvm_bc_basename = try std.fmt.allocPrint(arena, "{s}.bc", .{root_name});
+    var emit_llvm_bc_resolved = emit_llvm_bc.resolve(default_llvm_bc_basename) catch |err| {
+        switch (emit_llvm_bc) {
+            .yes => {
+                fatal("unable to open directory from argument '-femit-llvm-bc', '{s}': {s}", .{ emit_llvm_bc.yes, @errorName(err) });
+            },
+            .yes_default_path => {
+                fatal("unable to open directory from arguments '--name' or '-fsoname', '{s}': {s}", .{ default_llvm_bc_basename, @errorName(err) });
+            },
+            .no => unreachable,
+        }
+    };
+    defer emit_llvm_bc_resolved.deinit();
+
     const default_analysis_basename = try std.fmt.allocPrint(arena, "{s}-analysis.json", .{root_name});
     var emit_analysis_resolved = emit_analysis.resolve(default_analysis_basename) catch |err| {
         switch (emit_analysis) {
@@ -1988,6 +2011,7 @@ fn buildOutputType(
         .emit_h = emit_h_resolved.data,
         .emit_asm = emit_asm_resolved.data,
         .emit_llvm_ir = emit_llvm_ir_resolved.data,
+        .emit_llvm_bc = emit_llvm_bc_resolved.data,
         .emit_docs = emit_docs_resolved.data,
         .emit_analysis = emit_analysis_resolved.data,
         .link_mode = link_mode,