From 1f5486096816872ef01eb7ec235cee4a6a4ebc82 Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Mon, 4 Mar 2024 20:27:05 +0100
Subject: [PATCH] wasm-unknown: add math builtins that LLVM needs

---
 builder/build.go          |  7 +++++
 builder/wasmbuiltins.go   | 66 +++++++++++++++++++++++++++++++++++++++
 compileopts/config.go     |  2 ++
 targets/wasm-unknown.json |  1 +
 4 files changed, 76 insertions(+)
 create mode 100644 builder/wasmbuiltins.go

diff --git a/builder/build.go b/builder/build.go
index b9965c1e85..321400433d 100644
--- a/builder/build.go
+++ b/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 {
diff --git a/builder/wasmbuiltins.go b/builder/wasmbuiltins.go
new file mode 100644
index 0000000000..a48123b146
--- /dev/null
+++ b/builder/wasmbuiltins.go
@@ -0,0 +1,66 @@
+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",
+			"-I" + headerPath,
+		}
+	},
+	sourceDir: func() string { return filepath.Join(goenv.Get("TINYGOROOT"), "lib/wasi-libc") },
+	librarySources: func(target string) ([]string, error) {
+		return []string{
+			"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
+	},
+}
+
+const wasmAllTypes = `
+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 double double_t;
+`
diff --git a/compileopts/config.go b/compileopts/config.go
index 9349738a4a..24da4e280d 100644
--- a/compileopts/config.go
+++ b/compileopts/config.go
@@ -311,6 +311,8 @@ func (c *Config) CFlags(libclang bool) []string {
 	case "wasi-libc":
 		root := goenv.Get("TINYGOROOT")
 		cflags = append(cflags, "--sysroot="+root+"/lib/wasi-libc/sysroot")
+	case "wasmbuiltins":
+		// nothing to add (library is purely for builtins)
 	case "mingw-w64":
 		root := goenv.Get("TINYGOROOT")
 		path, _ := c.LibcPath("mingw-w64")
diff --git a/targets/wasm-unknown.json b/targets/wasm-unknown.json
index 903afa49e8..a3f6313c19 100644
--- a/targets/wasm-unknown.json
+++ b/targets/wasm-unknown.json
@@ -7,6 +7,7 @@
 	"goarch":        "arm",
 	"linker":        "wasm-ld",
 	"rtlib":         "compiler-rt",
+	"libc":          "wasmbuiltins",
 	"scheduler":     "none",
 	"gc":            "leaking",
 	"default-stack-size": 4096,