compiler: move ApplyFunctionSections to transform package

transform/globals.go

@@ -0,0 +1,20 @@
+package transform
+
+import "tinygo.org/x/go-llvm"
+
+// This file implements small transformations on globals (functions and global
+// variables) for specific ABIs/architectures.
+
+// ApplyFunctionSections puts every function in a separate section. This makes
+// it possible for the linker to remove dead code. It is the equivalent of
+// passing -ffunction-sections to a C compiler.
+func ApplyFunctionSections(mod llvm.Module) {
+	llvmFn := mod.FirstFunction()
+	for !llvmFn.IsNil() {
+		if !llvmFn.IsDeclaration() {
+			name := llvmFn.Name()
+			llvmFn.SetSection(".text." + name)
+		}
+		llvmFn = llvm.NextFunction(llvmFn)
+	}
+}

transform/globals_test.go

@@ -0,0 +1,14 @@
+package transform
+
+import (
+	"testing"
+
+	"tinygo.org/x/go-llvm"
+)
+
+func TestApplyFunctionSections(t *testing.T) {
+	t.Parallel()
+	testTransform(t, "testdata/globals-function-sections", func(mod llvm.Module) {
+		ApplyFunctionSections(mod)
+	})
+}

transform/testdata/globals-function-sections.ll

@@ -0,0 +1,8 @@
+target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "armv7em-none-eabi"
+
+declare void @foo()
+
+define void @bar() {
+  ret void
+}

transform/testdata/globals-function-sections.out.ll

@@ -0,0 +1,8 @@
+target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "armv7em-none-eabi"
+
+declare void @foo()
+
+define void @bar() section ".text.bar" {
+  ret void
+}