Starting with exception handling

lib/crystal/codegen.rb

@@ -70,6 +70,7 @@ def initialize(mod, node, return_type, filename = nil, debug = false, llvm_mod =
       @const_block_entry = @const_block
 
       @vars = {}
+      @exception_handlers = []
       @block_context = []
       @type = @mod
 
@@ -1108,6 +1109,21 @@ def codegen_yield(node, scope)
       end
     end
 
+    def visit_exception_handler(node)
+
+      catch_block = new_block "catch"
+
+      @exception_handlers << { node: node, catch_block: catch_block }
+      accept(node.body)
+      @exception_handlers.pop
+
+      @builder.position_at_end catch_block
+      @builder.landingpad LLVM::Struct(LLVM::Pointer(LLVM::Int8), LLVM::Int32), @llvm_mod.functions['__crystal_personality'], []
+      accept(node.rescues.first)
+
+      false
+    end
+
     def codegen_call(node, self_type, call_args)
       target_def = node.target_def
       mangled_name = target_def.mangled_name(self_type)
@@ -1136,7 +1152,14 @@ def codegen_call(node, self_type, call_args)
         end
       end
 
-      @last = @builder.call fun, *call_args
+      if @exception_handlers.empty?
+        @last = @builder.call fun, *call_args
+      else
+        handler = @exception_handlers.last
+        invoke_out_block = new_block "invoke_out"
+        @last = @builder.invoke fun, call_args, invoke_out_block, handler[:catch_block]
+        @builder.position_at_end invoke_out_block
+      end
 
       if has_struct_or_union_out_args
         call_args.each_with_index do |call_arg, i|
@@ -1164,8 +1187,10 @@ def codegen_fun(mangled_name, target_def, self_type)
       old_type = @type
       old_entry_block = @entry_block
       old_alloca_block = @alloca_block
+      old_exception_handlers = @exception_handlers
 
       @vars = {}
+      @exception_handlers = []
 
       args = []
       if self_type && self_type.passed_as_self?
@@ -1245,6 +1270,7 @@ def codegen_fun(mangled_name, target_def, self_type)
       end
 
       @vars = old_vars
+      @exception_handlers = old_exception_handlers
       @type = old_type
       @entry_block = old_entry_block
       @alloca_block = old_alloca_block

lib/crystal/codegen/crystal_llvm_builder.rb

@@ -5,6 +5,14 @@ def initialize(builder, codegen)
       @codegen = codegen
     end
 
+    def landingpad(type, personality, clauses, name = "")
+      lpad = LLVM::C.build_landing_pad @builder, type, personality, clauses.length, name
+      LLVM::C.set_cleanup lpad, 1
+      clauses.each do |clause|
+        LLVM::C.add_clause lpad, clause
+      end
+    end
+
     def ret(*args)
       return if @end
       @builder.ret *args

lib/crystal/type_inference.rb

@@ -952,6 +952,15 @@ def visit_pointer_cast(node)
       end
     end
 
+    def visit_exception_handler(node)
+      node.bind_to node.body
+      if node.rescues
+        node.rescues.each do |a_rescue|
+          node.bind_to a_rescue.body
+        end
+      end
+    end
+
     def lookup_var(name)
       var = @vars[name]
       unless var

spec/codegen/exception_spec.rb

@@ -0,0 +1,27 @@
+require 'spec_helper'
+
+describe 'Codegen: exceptin' do
+
+  it "executes normally the main block" do
+    run(%q(
+      begin
+        1
+      rescue
+        2
+      end
+    )).to_i.should eq(1)
+  end
+
+  it "executes rescue all block" do
+    run(%q(
+      require "prelude"
+      begin
+        raise 1
+        1
+      rescue
+        2
+      end
+    )).to_i.should eq(2)
+  end
+
+end

spec/type_inference/exception_spec.rb

@@ -0,0 +1,13 @@
+require 'spec_helper'
+
+describe 'Type inference: exception' do
+  it "type is union of main and rescue blocks" do
+    assert_type(%(
+      begin
+        1
+      rescue
+        'a'
+      end
+    )) { union_of(int32, char) }
+  end
+end

std/prelude.cr

@@ -24,11 +24,4 @@ require "string_builder"
 require "symbol"
 require "argv"
 require "time"
-
-def raise(msg)
-  print "ERROR: "
-  print msg.to_s
-  puts
-
-  exit 1
-end
+require "raise"

std/raise.cr

@@ -0,0 +1,53 @@
+lib ABI
+  struct UnwindException
+    exception_class : UInt64
+    exception_cleanup : Void*
+    private1 : UInt64
+    private2 : UInt64
+  end
+
+  UA_SEARCH_PHASE = 1
+  UA_CLEANUP_PHASE = 2
+  UA_HANDLER_FRAME = 4
+  UA_FORCE_UNWIND = 8
+
+  URC_NO_REASON = 0
+  URC_FOREIGN_EXCEPTION_CAUGHT = 1
+  URC_FATAL_PHASE2_ERROR = 2
+  URC_FATAL_PHASE1_ERROR = 3
+  URC_NORMAL_STOP = 4
+  URC_END_OF_STACK = 5
+  URC_HANDLER_FOUND = 6
+  URC_INSTALL_CONTEXT = 7
+  URC_CONTINUE_UNWIND = 8
+
+  fun unwind_raise_exception = _Unwind_RaiseException(ex : UnwindException*) : Int32
+end
+
+
+fun __crystal_personality(version : Int32, actions : Int32, exception_class : UInt64, exception_object : ABI::UnwindException*, context : Void*) : Int32
+  puts "PERSONALITY: version: #{version}, actions: #{actions}, exception_class: #{exception_class}, exception_object: #{exception_object.address}"
+  if (actions & ABI::UA_SEARCH_PHASE) > 0
+    return ABI::URC_HANDLER_FOUND
+  elsif (actions & ABI::UA_HANDLER_FRAME) > 0
+    puts "??"
+    return ABI::URC_INSTALL_CONTEXT
+  else
+    ABI::URC_NO_REASON
+  end
+end
+
+
+# u = ABI::UnwindException.new
+# personality(1, 1, 0_u64, u.ptr, Pointer(Void).malloc(1))
+
+
+def raise(msg)
+  puts "Raising..."
+  ex = ABI::UnwindException.new
+  ex.exception_class = 0_u64
+  # ex.exception_cleanup = nil
+  ABI.unwind_raise_exception(ex.ptr)
+
+  exit 1
+end