wasm-unknown: add math and memory builtins that LLVM needs

This new library is needed for wasm targets that aren't WASI and don't
need/want a libc, but still need some intrinsics that are generated by
LLVM.

builder/build.go

@@ -168,6 +168,13 @@ func Build(pkgName, outpath, tmpdir string, config *compileopts.Config) (BuildRe
 			return BuildResult{}, errors.New("could not find wasi-libc, perhaps you need to run `make wasi-libc`?")
 		}
 		libcDependencies = append(libcDependencies, dummyCompileJob(path))
+	case "wasmbuiltins":
+		libcJob, unlock, err := WasmBuiltins.load(config, tmpdir)
+		if err != nil {
+			return BuildResult{}, err
+		}
+		defer unlock()
+		libcDependencies = append(libcDependencies, libcJob)
 	case "mingw-w64":
 		_, unlock, err := MinGW.load(config, tmpdir)
 		if err != nil {

builder/wasmbuiltins.go

@@ -0,0 +1,79 @@
+package builder
+
+import (
+	"os"
+	"path/filepath"
+
+	"github.com/tinygo-org/tinygo/goenv"
+)
+
+var WasmBuiltins = Library{
+	name: "wasmbuiltins",
+	makeHeaders: func(target, includeDir string) error {
+		os.Mkdir(includeDir+"/bits", 0o777)
+		f, err := os.Create(includeDir + "/bits/alltypes.h")
+		if err != nil {
+			return err
+		}
+		if _, err := f.Write([]byte(wasmAllTypes)); err != nil {
+			return err
+		}
+		return f.Close()
+	},
+	cflags: func(target, headerPath string) []string {
+		libcDir := filepath.Join(goenv.Get("TINYGOROOT"), "lib/wasi-libc")
+		return []string{
+			"-Werror",
+			"-Wall",
+			"-std=gnu11",
+			"-nostdlibinc",
+			"-isystem", libcDir + "/libc-top-half/musl/arch/wasm32",
+			"-isystem", libcDir + "/libc-top-half/musl/arch/generic",
+			"-isystem", libcDir + "/libc-top-half/musl/src/internal",
+			"-isystem", libcDir + "/libc-top-half/musl/src/include",
+			"-isystem", libcDir + "/libc-top-half/musl/include",
+			"-isystem", libcDir + "/libc-bottom-half/headers/public",
+			"-I" + headerPath,
+		}
+	},
+	sourceDir: func() string { return filepath.Join(goenv.Get("TINYGOROOT"), "lib/wasi-libc") },
+	librarySources: func(target string) ([]string, error) {
+		return []string{
+			// memory builtins needed for llvm.memcpy.*, llvm.memmove.*, and
+			// llvm.memset.* LLVM intrinsics.
+			"libc-top-half/musl/src/string/memcpy.c",
+			"libc-top-half/musl/src/string/memmove.c",
+			"libc-top-half/musl/src/string/memset.c",
+
+			// exp, exp2, and log are needed for LLVM math builtin functions
+			// like llvm.exp.*.
+			"libc-top-half/musl/src/math/__math_divzero.c",
+			"libc-top-half/musl/src/math/__math_invalid.c",
+			"libc-top-half/musl/src/math/__math_oflow.c",
+			"libc-top-half/musl/src/math/__math_uflow.c",
+			"libc-top-half/musl/src/math/__math_xflow.c",
+			"libc-top-half/musl/src/math/exp.c",
+			"libc-top-half/musl/src/math/exp_data.c",
+			"libc-top-half/musl/src/math/exp2.c",
+			"libc-top-half/musl/src/math/log.c",
+			"libc-top-half/musl/src/math/log_data.c",
+		}, nil
+	},
+}
+
+// alltypes.h for wasm-libc, using the types as defined inside Clang.
+const wasmAllTypes = `
+typedef __SIZE_TYPE__    size_t;
+typedef __INT8_TYPE__    int8_t;
+typedef __INT16_TYPE__   int16_t;
+typedef __INT32_TYPE__   int32_t;
+typedef __INT64_TYPE__   int64_t;
+typedef __UINT8_TYPE__   uint8_t;
+typedef __UINT16_TYPE__  uint16_t;
+typedef __UINT32_TYPE__  uint32_t;
+typedef __UINT64_TYPE__  uint64_t;
+typedef __UINTPTR_TYPE__ uintptr_t;
+
+// This type is used internally in wasi-libc.
+typedef double double_t;
+`