break and continue in loops

compiler/llvm/llvm.odin

@@ -652,12 +652,18 @@ emit_instruction_stream :: proc(
 	sret_name := "",
 ) -> ir.Instruction_Id {
 	return_value := ir.INVALID_INSTRUCTION
-	after_return := false
+	// Set after any terminator (`ret`, `br`, conditional `br`). Code reachable
+	// only by falling off a terminator is dead; it needs a fresh label to form a
+	// well-formed basic block — unless the next instruction is already a `.Label`,
+	// which opens its own block (the normal terminator-then-label sequence).
+	after_terminator := false
 	for instruction, instruction_index in instructions {
 		instruction_id := ir.instruction_id(instruction_index)
-		if after_return {
-			fmt.sbprintf(&emitter.builder, "recover_after_return_%d:\n", instruction_index)
-			after_return = false
+		if after_terminator {
+			if instruction.op != .Label {
+				fmt.sbprintf(&emitter.builder, "recover_after_return_%d:\n", instruction_index)
+			}
+			after_terminator = false
 		}
 		switch instruction.op {
 		case .Param, .Const:
@@ -1662,14 +1668,17 @@ emit_instruction_stream :: proc(
 			fmt.sbprintf(&emitter.builder, "bro_block_%d:\n", instruction.integer)
 		case .Br:
 			fmt.sbprintf(&emitter.builder, "  br label %%bro_block_%d\n", instruction.integer)
+			after_terminator = true
 		case .Cond_Br:
 			if !valid_value(instructions, instruction.a, types.BOOL, &emitter.module.types) {
 				fmt.sbprintf(&emitter.builder, "  br label %%bro_block_%d\n", u32(instruction.target))
+				after_terminator = true
 				continue
 			}
 			strings.write_string(&emitter.builder, "  br i1 ")
 			write_operand(&emitter.builder, instructions, instruction.a, types.BOOL, &emitter.module.types)
 			fmt.sbprintf(&emitter.builder, ", label %%bro_block_%d, label %%bro_block_%d\n", instruction.integer, u32(instruction.target))
+			after_terminator = true
 		case .Trap:
 			message := diagnostic_message(emitter, instruction.diagnostic, instruction.span, "invalid recovered source")
 			emit_trap_call(emitter, message)
@@ -1703,7 +1712,7 @@ emit_instruction_stream :: proc(
 				write_operand(&emitter.builder, instructions, instruction.a, function.result, &emitter.module.types)
 				strings.write_string(&emitter.builder, "\n")
 			}
-			after_return = true
+			after_terminator = true
 		case .Return_Void:
 			if global_initializer {
 				continue
@@ -1713,7 +1722,7 @@ emit_instruction_stream :: proc(
 			} else {
 				strings.write_string(&emitter.builder, "  ret void\n")
 			}
-			after_return = true
+			after_terminator = true
 		}
 	}
 	return return_value