From f2abce7ea58decf10255bdfea14740578068dd4a Mon Sep 17 00:00:00 2001
From: Nikolay Nikolov <nickysn@gmail.com>
Date: Tue, 28 Sep 2021 20:23:27 +0300
Subject: [PATCH] + initial implementation of try..except..end in wasm native
 exceptions mode.   The 'on' statements are not implemented yet.

---
 compiler/wasm32/nwasmflw.pas | 102 ++++++++++++++++++++++++++++++++++-
 1 file changed, 101 insertions(+), 1 deletion(-)

diff --git a/compiler/wasm32/nwasmflw.pas b/compiler/wasm32/nwasmflw.pas
index 4c016a1ef7..cea1902b58 100644
--- a/compiler/wasm32/nwasmflw.pas
+++ b/compiler/wasm32/nwasmflw.pas
@@ -88,7 +88,7 @@ implementation
       symconst,symdef,symsym,aasmtai,aasmdata,aasmcpu,defutil,defcmp,
       procinfo,cgbase,cgexcept,pass_1,pass_2,parabase,compinnr,
       cpubase,cpuinfo,
-      nbas,nld,ncon,ncnv,ncal,ninl,nmem,nadd,
+      nbas,nld,ncon,ncnv,ncal,ninl,nmem,nadd,nutils,
       tgobj,paramgr,
       cgutils,hlcgobj,hlcgcpu;
 
@@ -365,9 +365,109 @@ implementation
       end;
 
     procedure twasmtryexceptnode.pass_generate_code_native_exceptions;
+      var
+        trystate,doobjectdestroyandreraisestate: tcgexceptionstatehandler.texceptionstate;
+        destroytemps,
+        excepttemps: tcgexceptionstatehandler.texceptiontemps;
+        afteronflowcontrol: tflowcontrol;
+      label
+        errorexit;
       begin
         location_reset(location,LOC_VOID,OS_NO);
+
+        { Exception temps? We don't need no stinking exception temps! :) }
+        fillchar(excepttemps,sizeof(excepttemps),0);
+        reference_reset(excepttemps.envbuf,0,[]);
+        reference_reset(excepttemps.jmpbuf,0,[]);
+        reference_reset(excepttemps.reasonbuf,0,[]);
+
+        //exceptstate.oldflowcontrol:=flowcontrol;
+        //flowcontrol:=[fc_inflowcontrol,fc_catching_exceptions];
+        cexceptionstatehandler.new_exception(current_asmdata.CurrAsmList,excepttemps,tek_except,trystate);
+
+        current_asmdata.CurrAsmList.concat(taicpu.op_none(a_try));
+        thlcgwasm(hlcg).incblock;
+
+        { try block }
         secondpass(left);
+        if codegenerror then
+          goto errorexit;
+
+        //exceptionstate.newflowcontrol:=flowcontrol;
+        //flowcontrol:=exceptionstate.oldflowcontrol;
+        cexceptionstatehandler.end_try_block(current_asmdata.CurrAsmList,tek_except,excepttemps,trystate,nil);
+
+        current_asmdata.CurrAsmList.concat(taicpu.op_sym(a_catch,current_asmdata.WeakRefAsmSymbol(FPC_EXCEPTION_TAG_SYM,AT_WASM_EXCEPTION_TAG)));
+
+        flowcontrol:=[fc_inflowcontrol]+trystate.oldflowcontrol*[fc_catching_exceptions];
+        { on statements }
+        //if assigned(right) then
+        //  secondpass(right);
+
+        afteronflowcontrol:=flowcontrol;
+
+        { default handling except handling }
+        if assigned(t1) then
+          begin
+            { FPC_CATCHES with 'default handler' flag (=-1) need no longer be called,
+              it doesn't change any state and its return value is ignored (Sergei)
+            }
+
+            { the destruction of the exception object must be also }
+            { guarded by an exception frame, but it can be omitted }
+            { if there's no user code in 'except' block            }
+
+            if not (has_no_code(t1)) then
+              begin
+                { if there is an outer frame that catches exceptions, remember this for the "except"
+                  part of this try/except }
+                flowcontrol:=trystate.oldflowcontrol*[fc_inflowcontrol,fc_catching_exceptions];
+                { Exception temps? We don't need no stinking exception temps! :) }
+                fillchar(excepttemps,sizeof(destroytemps),0);
+                reference_reset(destroytemps.envbuf,0,[]);
+                reference_reset(destroytemps.jmpbuf,0,[]);
+                reference_reset(destroytemps.reasonbuf,0,[]);
+                cexceptionstatehandler.new_exception(current_asmdata.CurrAsmList,destroytemps,tek_except,doobjectdestroyandreraisestate);
+                { the flowcontrol from the default except-block must be merged
+                  with the flowcontrol flags potentially set by the
+                  on-statements handled above (secondpass(right)), as they are
+                  at the same program level }
+                flowcontrol:=
+                  flowcontrol+
+                  afteronflowcontrol;
+
+                current_asmdata.CurrAsmList.concat(taicpu.op_none(a_try));
+                thlcgwasm(hlcg).incblock;
+
+                secondpass(t1);
+
+                hlcg.g_call_system_proc(current_asmdata.CurrAsmList,'fpc_doneexception',[],nil).resetiftemp;
+
+                current_asmdata.CurrAsmList.concat(taicpu.op_sym(a_catch,current_asmdata.WeakRefAsmSymbol(FPC_EXCEPTION_TAG_SYM,AT_WASM_EXCEPTION_TAG)));
+
+                hlcg.g_call_system_proc(current_asmdata.CurrAsmList,'fpc_raise_nested',[],nil).resetiftemp;
+
+                current_asmdata.CurrAsmList.concat(taicpu.op_none(a_end_try));
+              end
+            else
+              begin
+                doobjectdestroyandreraisestate.newflowcontrol:=afteronflowcontrol;
+                hlcg.g_call_system_proc(current_asmdata.CurrAsmList,'fpc_doneexception',[],nil).resetiftemp;
+              end;
+          end
+        else
+          begin
+            current_asmdata.CurrAsmList.concat(taicpu.op_const(a_rethrow,0));
+            doobjectdestroyandreraisestate.newflowcontrol:=afteronflowcontrol;
+          end;
+
+        current_asmdata.CurrAsmList.concat(taicpu.op_none(a_end_try));
+        thlcgwasm(hlcg).decblock;
+
+      errorexit:
+        { return all used control flow statements }
+        flowcontrol:=trystate.oldflowcontrol+(doobjectdestroyandreraisestate.newflowcontrol +
+          trystate.newflowcontrol - [fc_inflowcontrol,fc_catching_exceptions]);
       end;
 
     procedure twasmtryexceptnode.pass_generate_code;