From 8cd6606970c8fedda95a3411d684dbd57379b46d Mon Sep 17 00:00:00 2001
From: Nikolay Nikolov <nickysn@gmail.com>
Date: Sun, 11 Jun 2023 07:17:04 +0300
Subject: [PATCH] + support nil comparison of WebAssembly reference types
 (externref and funcref)

---
 compiler/nadd.pas                  | 14 ++++++--
 compiler/wasm32/hlcgcpu.pas        | 51 +++++++++++++++++++++++++++---
 tests/test/wasm/twasmexternref1.pp | 10 ++++++
 tests/test/wasm/twasmfuncref1.pp   | 10 ++++++
 4 files changed, 79 insertions(+), 6 deletions(-)

diff --git a/compiler/nadd.pas b/compiler/nadd.pas
index 77e9cfc464..473a839233 100644
--- a/compiler/nadd.pas
+++ b/compiler/nadd.pas
@@ -2675,9 +2675,9 @@ implementation
             case nodetype of
                equaln,unequaln :
                  begin
-                    if is_voidpointer(right.resultdef) then
+                    if is_voidpointer(right.resultdef) and (left.nodetype<>niln) then
                       inserttypeconv(right,left.resultdef)
-                    else if is_voidpointer(left.resultdef) then
+                    else if is_voidpointer(left.resultdef) and (right.nodetype<>niln) then
                       inserttypeconv(left,right.resultdef)
                     else if not(equal_defs(ld,rd)) then
                       IncompatibleTypes(ld,rd);
@@ -2704,6 +2704,16 @@ implementation
                       inserttypeconv_internal(right,charfarpointertype)
                     else
                       inserttypeconv_internal(right,charnearpointertype);
+{$elseif defined(wasm)}
+                    if is_wasm_reference_type(left.resultdef) then
+                      inserttypeconv(right,left.resultdef)
+                    else if is_wasm_reference_type(right.resultdef) then
+                      inserttypeconv(left,right.resultdef)
+                    else
+                      begin
+                        inserttypeconv_internal(left,charpointertype);
+                        inserttypeconv_internal(right,charpointertype);
+                      end;
 {$else}
                     inserttypeconv_internal(left,charpointertype);
                     inserttypeconv_internal(right,charpointertype);
diff --git a/compiler/wasm32/hlcgcpu.pas b/compiler/wasm32/hlcgcpu.pas
index 65575655df..dcccbbca0e 100644
--- a/compiler/wasm32/hlcgcpu.pas
+++ b/compiler/wasm32/hlcgcpu.pas
@@ -754,19 +754,62 @@ implementation
   procedure thlcgwasm.a_cmp_const_ref_stack(list: TAsmList; size: tdef; cmp_op: topcmp; a: tcgint; const ref: treference);
     var
       tmpref: treference;
+      regtyp: TRegisterType;
     begin
       tmpref:=ref;
       if tmpref.base<>NR_EVAL_STACK_BASE then
         a_load_ref_stack(list,size,tmpref,prepare_stack_for_ref(list,tmpref,false));
-      a_load_const_stack(list,size,a,def2regtyp(size));
-      a_cmp_stack_stack(list,size,cmp_op);
+      regtyp:=def2regtyp(size);
+      case regtyp of
+        R_EXTERNREFREGISTER,
+        R_FUNCREFREGISTER:
+          begin
+            if a<>0 then
+              internalerror(2023061103);
+            if not (cmp_op in [OC_EQ,OC_NE]) then
+              internalerror(2023061104);
+            list.Concat(taicpu.op_none(a_ref_is_null));
+            if cmp_op=OC_NE then
+              begin
+                a_load_const_stack(list,s32inttype,0,R_INTREGISTER);
+                a_cmp_stack_stack(list,s32inttype,OC_EQ);
+              end;
+          end;
+        else
+          begin
+            a_load_const_stack(list,size,a,regtyp);
+            a_cmp_stack_stack(list,size,cmp_op);
+          end;
+      end;
     end;
 
   procedure thlcgwasm.a_cmp_const_reg_stack(list: TAsmList; size: tdef; cmp_op: topcmp; a: tcgint; reg: tregister);
+    var
+      regtyp: TRegisterType;
     begin
       a_load_reg_stack(list,size,reg);
-      a_load_const_stack(list,size,a,def2regtyp(size));
-      a_cmp_stack_stack(list,size,cmp_op);
+      regtyp:=def2regtyp(size);
+      case regtyp of
+        R_EXTERNREFREGISTER,
+        R_FUNCREFREGISTER:
+          begin
+            if a<>0 then
+              internalerror(2023061105);
+            if not (cmp_op in [OC_EQ,OC_NE]) then
+              internalerror(2023061106);
+            list.Concat(taicpu.op_none(a_ref_is_null));
+            if cmp_op=OC_NE then
+              begin
+                a_load_const_stack(list,s32inttype,0,R_INTREGISTER);
+                a_cmp_stack_stack(list,s32inttype,OC_EQ);
+              end;
+          end;
+        else
+          begin
+            a_load_const_stack(list,size,a,regtyp);
+            a_cmp_stack_stack(list,size,cmp_op);
+          end;
+      end;
     end;
 
   procedure thlcgwasm.a_cmp_ref_reg_stack(list: TAsmList; size: tdef; cmp_op: topcmp; const ref: treference; reg: tregister);
diff --git a/tests/test/wasm/twasmexternref1.pp b/tests/test/wasm/twasmexternref1.pp
index e8ed9f7186..db786f5a23 100644
--- a/tests/test/wasm/twasmexternref1.pp
+++ b/tests/test/wasm/twasmexternref1.pp
@@ -33,6 +33,16 @@ begin
   testproc5 := nil;
 end;
 
+function testproc6: Boolean;
+var
+  q: WasmExternRef;
+begin
+  testproc6 := q = nil;
+  testproc6 := nil = q;
+  testproc6 := q <> nil;
+  testproc6 := nil <> q;
+end;
+
 begin
   testproc5(nil);
 end.
diff --git a/tests/test/wasm/twasmfuncref1.pp b/tests/test/wasm/twasmfuncref1.pp
index f3743a68b6..6042d8995f 100644
--- a/tests/test/wasm/twasmfuncref1.pp
+++ b/tests/test/wasm/twasmfuncref1.pp
@@ -38,6 +38,16 @@ begin
   testproc5 := nil;
 end;
 
+function testproc6: Boolean;
+var
+  q: TWasmFuncRef;
+begin
+  testproc6 := q = nil;
+  testproc6 := nil = q;
+  testproc6 := q <> nil;
+  testproc6 := nil <> q;
+end;
+
 begin
   testproc5(nil);
 end.