closureStub: SetTailCall

cl/_testrt/callback/out.ll

@@ -57,7 +57,7 @@ declare void @"github.com/goplus/llgo/internal/runtime.init"()
 
 define linkonce void @__llgo_stub.main.print(ptr %0, ptr %1) {
 _llgo_0:
-  call void @main.print(ptr %1)
+  tail call void @main.print(ptr %1)
   ret void
 }
 

cl/_testrt/closure/out.ll

@@ -56,7 +56,7 @@ _llgo_0:
 
 define linkonce void @"__llgo_stub.main.main$1"(ptr %0, i64 %1, i64 %2) {
 _llgo_0:
-  call void @"main.main$1"(i64 %1, i64 %2)
+  tail call void @"main.main$1"(i64 %1, i64 %2)
   ret void
 }
 

cl/_testrt/intgen/out.ll

@@ -165,7 +165,7 @@ declare i32 @rand()
 
 define linkonce i32 @__llgo_stub.rand(ptr %0) {
 _llgo_0:
-  %1 = call i32 @rand()
+  %1 = tail call i32 @rand()
   ret i32 %1
 }
 

ssa/package.go

@@ -388,6 +388,7 @@ func (p Package) closureStub(b Builder, t *types.Struct, v Expr) Expr {
 		}
 		b := fn.MakeBody(1)
 		call := b.Call(v, args...)
+		call.impl.SetTailCall(true)
 		switch nret {
 		case 0:
 			b.impl.CreateRetVoid()