Basic support for Win64 C lib ABI (#9387)

* Split general ABI specs from x86_64-specific ones, run on every platform

To confirm that the newly added file only moves things:

    $ git diff -w HEAD~:spec/compiler/codegen/c_abi/c_abi_x86_64_spec.cr spec/compiler/codegen/c_abi/c_abi_spec.cr

* Implement basics of Win64 lib ABI

Also un-does #5851

Author: oprypin

spec/compiler/codegen/c_abi/c_abi_spec.cr

@@ -32,11 +32,11 @@ describe "Code gen: C ABI" do
     test_c(
       %(
         struct s {
-          long x;
+          long long x;
           short y;
         };
 
-        long foo(struct s a) {
+        long long foo(struct s a) {
           return a.x + a.y;
         }
       ),
@@ -59,12 +59,12 @@ describe "Code gen: C ABI" do
     test_c(
       %(
         struct s {
-          long x;
-          long y;
+          long long x;
+          long long y;
           char z;
         };
 
-        long foo(struct s a) {
+        long long foo(struct s a) {
           return a.x + a.y + a.z;
         }
       ),
@@ -116,7 +116,7 @@ describe "Code gen: C ABI" do
     test_c(
       %(
         struct s {
-          long x;
+          long long x;
           short y;
         };
 
@@ -144,8 +144,8 @@ describe "Code gen: C ABI" do
     test_c(
       %(
         struct s {
-          long x;
-          long y;
+          long long x;
+          long long y;
           char z;
         };
 

spec/compiler/codegen/c_abi/c_abi_x86_64_spec.cr

@@ -1,6 +1,6 @@
 require "../../../spec_helper"
 
-{% if flag?(:x86_64) %}
+{% if flag?(:x86_64) && !flag?(:win32) %}
   describe "Code gen: C ABI x86_64" do
     it "passes struct less than 64 bits as { i64 }" do
       mod = codegen(%(

spec/compiler/codegen/extern_spec.cr

@@ -431,9 +431,9 @@ describe "Codegen: extern struct" do
       test_c(
         %(
             struct Struct {
-              long x;
-              long y;
-              long z;
+              long long x;
+              long long y;
+              long long z;
             };
 
             struct Struct foo(struct Struct (*callback)(struct Struct)) {

spec/compiler/codegen/primitives_spec.cr

@@ -239,22 +239,25 @@ describe "Code gen: primitives" do
   end
 
   describe "va_arg" do
-    it "uses llvm's va_arg instruction" do
-      mod = codegen(%(
-        struct VaList
-          @[Primitive(:va_arg)]
-          def next(type)
+    # On Windows llvm's va_arg instruction works incorrectly.
+    {% unless flag?(:win32) %}
+      it "uses llvm's va_arg instruction" do
+        mod = codegen(%(
+          struct VaList
+            @[Primitive(:va_arg)]
+            def next(type)
+            end
           end
-        end
 
-        list = VaList.new
-        list.next(Int32)
-      ))
-      str = mod.to_s
-      str.should contain("va_arg %VaList* %list")
-    end
+          list = VaList.new
+          list.next(Int32)
+        ))
+        str = mod.to_s
+        str.should contain("va_arg %VaList* %list")
+      end
+    {% end %}
 
-    it "works with C code" do
+    pending_win32 "works with C code" do
       test_c(
         %(
           extern int foo_f(int,...);

src/compiler/crystal/semantic/main_visitor.cr

@@ -2431,6 +2431,9 @@ module Crystal
     end
 
     def visit_va_arg(node)
+      if program.has_flag? "windows"
+        node.raise "va_arg is not yet supported on Windows"
+      end
       arg = call.not_nil!.args[0]? || node.raise("requires type argument")
       node.type = arg.type.instance_type
     end

src/llvm/abi.cr

@@ -1,3 +1,4 @@
+# Based on https://github.com/rust-lang/rust/blob/29ac04402d53d358a1f6200bea45a301ff05b2d1/src/librustc_trans/trans/cabi.rs
 abstract class LLVM::ABI
   getter target_data : TargetData
   getter? osx : Bool

src/llvm/abi/x86.cr

@@ -1,5 +1,6 @@
 require "../abi"
 
+# Based on https://github.com/rust-lang/rust/blob/29ac04402d53d358a1f6200bea45a301ff05b2d1/src/librustc_trans/trans/cabi_x86.rs
 class LLVM::ABI::X86 < LLVM::ABI
   def abi_info(atys : Array(Type), rty : Type, ret_def : Bool, context : Context)
     ret_ty = compute_return_type(rty, ret_def, context)

src/llvm/abi/x86_64.cr

@@ -1,5 +1,6 @@
 require "../abi"
 
+# Based on https://github.com/rust-lang/rust/blob/29ac04402d53d358a1f6200bea45a301ff05b2d1/src/librustc_trans/trans/cabi_x86_64.rs
 class LLVM::ABI::X86_64 < LLVM::ABI
   def abi_info(atys : Array(Type), rty : Type, ret_def : Bool, context : Context)
     arg_tys = Array(LLVM::Type).new(atys.size)

src/llvm/abi/x86_win64.cr

@@ -0,0 +1,22 @@
+require "../abi"
+
+# Based on https://github.com/rust-lang/rust/blob/29ac04402d53d358a1f6200bea45a301ff05b2d1/src/librustc_trans/trans/cabi_x86_win64.rs
+class LLVM::ABI::X86_Win64 < LLVM::ABI::X86
+  private def compute_arg_types(atys, context)
+    atys.map do |t|
+      case t.kind
+      when Type::Kind::Struct
+        size = target_data.abi_size(t)
+        case size
+        when 1 then ArgType.direct(t, context.int8)
+        when 2 then ArgType.direct(t, context.int16)
+        when 4 then ArgType.direct(t, context.int32)
+        when 8 then ArgType.direct(t, context.int64)
+        else        ArgType.indirect(t, LLVM::Attribute::ByVal)
+        end
+      else
+        non_struct(t, context)
+      end
+    end
+  end
+end

src/llvm/target_machine.cr

@@ -43,6 +43,8 @@ class LLVM::TargetMachine
   def abi
     triple = self.triple
     case triple
+    when /x86_64.+windows-msvc/
+      ABI::X86_Win64.new(self)
     when /x86_64|amd64/
       ABI::X86_64.new(self)
     when /i386|i486|i586|i686/