workaround for llvm.coro.save being broken

Author: niaow

transform/goroutine.go

@@ -689,11 +689,6 @@ func (c *coroutineLoweringPass) lowerFuncCoro(fn *asyncFunc) {
 		// Lower return value of call.
 		c.lowerCallReturn(fn, call)
 
-		// Save coroutine state before calling the function.
-		// %coro.save = call token @llvm.coro.save(i8* %coro.state)
-		c.builder.SetInsertPointBefore(call)
-		save := c.builder.CreateCall(c.coroSave, []llvm.Value{coroState}, "coro.save")
-
 		// Get originating basic block.
 		bb := call.InstructionParent()
 
@@ -702,6 +697,8 @@ func (c *coroutineLoweringPass) lowerFuncCoro(fn *asyncFunc) {
 
 		// Insert suspension and switch.
 		c.builder.SetInsertPointAtEnd(bb)
+		// %coro.save = call token @llvm.coro.save(i8* %coro.state)
+		save := c.builder.CreateCall(c.coroSave, []llvm.Value{coroState}, "coro.save")
 		// %call.suspend = llvm.coro.suspend(token %coro.save, i1 false)
 		// switch i8 %call.suspend, label %suspend [i8 0, label %wakeup
 		//                                          i8 1, label %cleanup]