all: remove support for LLVM 11 and LLVM 12

This removes a lot of backwards compatibility cruft and makes it
possible to start using features that need LLVM 13 or newer.
For example:

  * https://github.com/tinygo-org/tinygo/pull/2637
  * https://github.com/tinygo-org/tinygo/pull/2830

builder/build.go

@@ -935,17 +935,6 @@ func optimizeProgram(mod llvm.Module, config *compileopts.Config) error {
 		return errors.New("verification failure after LLVM optimization passes")
 	}
 
-	// LLVM 11 by default tries to emit tail calls (even with the target feature
-	// disabled) unless it is explicitly disabled with a function attribute.
-	// This is a problem, as it tries to emit them and prints an error when it
-	// can't with this feature disabled.
-	// Because as of september 2020 tail calls are not yet widely supported,
-	// they need to be disabled until they are widely supported (at which point
-	// the +tail-call target feautre can be set).
-	if strings.HasPrefix(config.Triple(), "wasm") {
-		transform.DisableTailCalls(mod)
-	}
-
 	return nil
 }
 

builder/builder_test.go

@@ -26,7 +26,7 @@ func TestClangAttributes(t *testing.T) {
 		"cortex-m0",
 		"cortex-m0plus",
 		"cortex-m3",
-		//"cortex-m33", // TODO: broken in LLVM 11, fixed in https://reviews.llvm.org/D90305
+		"cortex-m33",
 		"cortex-m4",
 		"cortex-m7",
 		"esp32c3",

builder/darwin-libsystem.go

@@ -6,7 +6,6 @@ import (
 
 	"github.com/tinygo-org/tinygo/compileopts"
 	"github.com/tinygo-org/tinygo/goenv"
-	"tinygo.org/x/go-llvm"
 )
 
 // Create a job that builds a Darwin libSystem.dylib stub library. This library
@@ -39,12 +38,8 @@ func makeDarwinLibSystemJob(config *compileopts.Config, tmpdir string) *compileJ
 
 			// Link object file to dynamic library.
 			platformVersion := strings.TrimPrefix(strings.Split(config.Triple(), "-")[2], "macosx")
-			flavor := "darwin"
-			if strings.Split(llvm.Version, ".")[0] < "13" {
-				flavor = "darwinnew" // needed on LLVM 12 and below
-			}
 			flags = []string{
-				"-flavor", flavor,
+				"-flavor", "darwin",
 				"-demangle",
 				"-dynamic",
 				"-dylib",

builder/tools-builtin.go

@@ -54,7 +54,7 @@ func RunTool(tool string, args ...string) error {
 		ok = C.tinygo_clang_driver(C.int(len(args)), (**C.char)(buf))
 	case "ld.lld":
 		switch linker {
-		case "darwin", "darwinnew": // darwinnew is only needed for LLVM 12 and below
+		case "darwin":
 			ok = C.tinygo_link_macho(C.int(len(args)), (**C.char)(buf))
 		case "elf":
 			ok = C.tinygo_link_elf(C.int(len(args)), (**C.char)(buf))