diff --git a/src/compiler/ir-gas64.bas b/src/compiler/ir-gas64.bas
index c076768761..50e9aa5c43 100644
--- a/src/compiler/ir-gas64.bas
+++ b/src/compiler/ir-gas64.bas
@@ -325,7 +325,7 @@ declare sub _emitscopebegin( byval s as FBSYMBOL ptr )
 declare sub _emitscopeend( byval s as FBSYMBOL ptr )
 declare sub _emitMacro( byval op as integer,byval v1 as IRVREG ptr, byval v2 as IRVREG ptr, byval vr as IRVREG ptr )
 declare sub save_call(byref func as string,byval vr as IRVREG ptr,byval vrreg as integer)
-declare sub struct_analyze(byval fld as FBSYMBOL ptr,byref class1 as integer,byref class2 as integer,byref limit as integer)
+declare function hGetMagicStructNumber( byval sym as FBSYMBOL ptr ) as integer
 ''===================== globals ===========================================
 dim shared as EDBGCTX       ctx_asm64
 dim shared as long          reghandle(KREGUPPER+2)
@@ -1753,17 +1753,13 @@ private sub memcopy(byval bytestoclear as Integer,byref src as string, byref dst
 		end if
 	end if
 
-	rnbb=reg_findfree(999996)
-	regnbb=*regstrq(rnbb)
-
-	if regsrc<>src then reghandle(rsrc)=KREGFREE :asm_info("hidden freeing register="+*regstrq(rsrc))''free registers
-	if regdst<>dst then reghandle(rdst)=KREGFREE :asm_info("hidden freeing register="+*regstrq(rdst))
-	reghandle(rnbb)=KREGFREE:asm_info("hidden freeing register="+*regstrq(rnbb))
-
 	nb8=nbbytes\8
 
 	''copy by 8 bytes step
 	if nb8>7 then ''greater than 7 times * 8 bytes
+		rnbb=reg_findfree(999996)
+		regnbb=*regstrq(rnbb)
+		reghandle(rnbb)=KREGFREE:asm_info("hidden freeing register="+*regstrq(rnbb))
 		asm_code("mov "+regnbb+", "+Str(nb8))
 
 		lname=*symbUniqueLabel( )
@@ -1818,6 +1814,10 @@ private sub memcopy(byval bytestoclear as Integer,byref src as string, byref dst
 		asm_code("mov al, byte ptr ["+regsrc+"]")
 		asm_code("mov byte ptr ["+regdst+"], al")
 	end if
+
+	if regsrc<>src then reghandle(rsrc)=KREGFREE :asm_info("hidden freeing register="+*regstrq(rsrc))''free registers
+	if regdst<>dst then reghandle(rdst)=KREGFREE :asm_info("hidden freeing register="+*regstrq(rdst))
+
 end sub
 
 private sub _init( )
@@ -2267,7 +2267,7 @@ private function param_analyze(byval dtype as FB_DATATYPE,byval struc as FBSYMBO
 	,byref cptarg as integer=0,byref cptint as integer=0,byref cptfloat as integer=0) as integer
 	''used in hdocall and also in procallocarg but here do not update cptarg/cptint/cptfloat.....
 	dim as FBSYMBOL ptr fld = any
-	dim as integer lgt,intcpt,floatcpt,class1,class2,limit
+	dim as integer lgt,intcpt,floatcpt
 
 	if ctx.target=FB_COMPTARGET_LINUX then
 		'' LNX =================================================================================
@@ -2294,41 +2294,35 @@ private function param_analyze(byval dtype as FB_DATATYPE,byval struc as FBSYMBO
 			lgt=struc->lgt
 			asm_info("subtype/lgt="+*symbGetMangledName(struc)+" "+str(lgt))
 			if lgt<=typeGetSize( FB_DATATYPE_LONGINT )*2 then
-				''by default floating point for first register
-				class1=2
-				class2=0
-				limit=7
-				struct_analyze(struc,class1,class2,limit)
-				asm_info("typeregister="+str(class1+class2))
-				select case as const class1+class2
-					case 1
+				select case as const hGetMagicStructNumber( struc )
+					case KSTRUCT_R
 						if cptint <6 then
 							cptint+=1
 							return KPARAMR1
 						end if
-					case 2
+					case KSTRUCT_X
 						if cptfloat <8 then
 							cptfloat+=1
 							return KPARAMX1
 						end if
-					case 5
+					case KSTRUCT_RR
 						if cptint <5 then
 							cptint+=2
 							return KPARAMRR
 						end if
-					case 9
+					case KSTRUCT_RX
 						if cptint <6 and cptfloat <8 then
 							cptint+=1
 							cptfloat+=1
 							return KPARAMRX
 						end if
-					case 6
+					case KSTRUCT_XR
 						if cptint <6 and cptfloat <8 then
 							cptfloat+=1
 							cptint+=1
 							return KPARAMXR
 						end if
-					case 10
+					case KSTRUCT_XX
 						if cptfloat <7 then
 							cptfloat+=2
 							return KPARAMXX
diff --git a/src/compiler/symb-struct.bas b/src/compiler/symb-struct.bas
index 47f7f13687..ecd855b140 100644
--- a/src/compiler/symb-struct.bas
+++ b/src/compiler/symb-struct.bas
@@ -639,26 +639,32 @@ sub symbInsertInnerUDT _
 end sub
 
 ''================================================
-'' for Linux structure parameters size<=16
+'' for Linux structure parameters size<=16 bytes
 ''================================================
-
-sub struct_analyze( byval fld as FBSYMBOL ptr, byref part1 as integer, byref part2 as integer, byref limit as integer )
+'' if the structure size is less or equal to 16 bytes it could be passed directly in registers according the datatype fields
+'' integers and floats could even be mixed using Rxx and Xmm
+'' analyzing the 8 low bytes then the 8 high bytes to know if each block contains integer or/and float
+'' if at least one integer field all the range is considered as integer
+'' if the size is greater than 8 and the result is only KPART1FLOAT or KPART1INTEGER then the structure is totally float or totally integer
+'' (the structure contains only an array of simple datatype) and the result is forced to KSTRUCT_XX or KSTRUCT_RR
+''================================================
+private sub struct_analyze( byval fld as FBSYMBOL ptr, byref part1 as integer, byref part2 as integer, byref range as integer )
 	
 	dim as integer lgt=fld->lgt
 	fld = symbUdtGetFirstField(fld)
 	while fld
-		if limit=7 and fld->ofs>7 then
-			limit+=8
-			part2=8
+		if range=KLOW8BYTES and fld->ofs>7 then
+			range = KHIGH8BYTES
+			part2 = KPART2FLOAT ''default
 		end if
 
 		if typegetclass(fld->typ)=FB_DATACLASS_UDT then
-			struct_analyze(fld->subtype,part1,part2,limit)
+			struct_analyze(fld->subtype,part1,part2,range)
 		elseif typegetclass(fld->typ)=FB_DATACLASS_INTEGER then
-			if limit=7 then
-				part1=1
+			if range=KLOW8BYTES then
+				part1=KPART1INTEGER
 			else
-				part2=4
+				part2=KPART2INTEGER
 			end if
 		end if
 		fld=symbUdtGetNextField(fld)
@@ -666,22 +672,21 @@ sub struct_analyze( byval fld as FBSYMBOL ptr, byref part1 as integer, byref par
 
 	if lgt>8 then
 		''case array in type eg type udt / array(0 to 1) as integer /end type
-		if part1+part2=1 then
-			part1=5
-		elseif part1+part2=2 then
-			part1=10
+		if part1+part2=KPART1INTEGER then
+			part1=KSTRUCT_RR
+		elseif part1+part2=KPART1FLOAT then
+			part1=KSTRUCT_XX
 		end if
 	end if
 
 end sub
-
-private function hGetMagicStructNumber( byval sym as FBSYMBOL ptr ) as integer
+function hGetMagicStructNumber( byval sym as FBSYMBOL ptr ) as integer
 	'' by default floating point for first register
-	dim as integer part1 = 2
-	dim as integer part2 = 0
-	dim as integer limit = 7
+	dim as integer part1 = KPART1FLOAT
+	dim as integer part2 = KPARTNOTDEF
+	dim as integer range = KLOW8BYTES
 
-	struct_analyze( sym, part1, part2, limit )
+	struct_analyze( sym, part1, part2, range )
 
 	return part1 + part2
 end function
@@ -695,24 +700,24 @@ private function hGetReturnTypeGas64Linux( byval sym as FBSYMBOL ptr ) as intege
 
 	if( sym->lgt <= typeGetSize( FB_DATATYPE_LONGINT ) * 2 ) then
 		select case as const hGetMagicStructNumber( sym )
-			case 1 ''only integers in RAX
+			case KSTRUCT_R ''only integers in RAX
 				'' don't set retin2regs, it's handled by datatype only 
 				'' sym->udt.retin2regs = FB_STRUCT_R
 				return FB_DATATYPE_LONGINT
-			case 2 ''only floats in XMM0
+			case KSTRUCT_X ''only floats in XMM0
 				'' don't set retin2regs, it's handled by datatype only
 				'' sym->udt.retin2regs = FB_STRUCT_X
 				return FB_DATATYPE_DOUBLE
-			case 5 ''only integers in RAX/RDX
+			case KSTRUCT_RR ''only integers in RAX/RDX
 				sym->udt.retin2regs = FB_STRUCT_RR
 				return FB_DATATYPE_STRUCT
-			case 9 ''first part in RAX then in XMMO
+			case KSTRUCT_RX ''first part in RAX then in XMMO
 				 sym->udt.retin2regs = FB_STRUCT_RX
 				 return FB_DATATYPE_STRUCT
-			case 6 ''first part in XMMO then in RAX
+			case KSTRUCT_XR ''first part in XMMO then in RAX
 				sym->udt.retin2regs = FB_STRUCT_XR
 				return typeAddrOf( FB_DATATYPE_STRUCT )
-			case 10 ''only floats in XMM0/XMM1
+			case KSTRUCT_XX ''only floats in XMM0/XMM1
 				sym->udt.retin2regs = FB_STRUCT_XX
 				return FB_DATATYPE_STRUCT
 			case else
diff --git a/src/compiler/symb.bi b/src/compiler/symb.bi
index 0dd36912e4..7aa6d5dde2 100644
--- a/src/compiler/symb.bi
+++ b/src/compiler/symb.bi
@@ -275,6 +275,21 @@ enum FB_STRUCT_INREG
 	FB_STRUCT_XX   ''XMM0/XMM1
 end enum
 
+''for analyzing structures Linux only
+#define KPARTNOTDEF 0
+#define KPART1FLOAT 2
+#define KPART2FLOAT 8
+#define KPART1INTEGER 1
+#define KPART2INTEGER 4
+#define KLOW8BYTES 1
+#define KHIGH8BYTES 2
+#define KSTRUCT_R  KPART1INTEGER
+#define KSTRUCT_X  KPART1FLOAT
+#define KSTRUCT_RR KPART1INTEGER + KPART2INTEGER
+#define KSTRUCT_RX KPART1INTEGER + KPART2FLOAT
+#define KSTRUCT_XR KPART1FLOAT   + KPART2INTEGER
+#define KSTRUCT_XX KPART1FLOAT   + KPART2FLOAT
+
 type FBSYMBOL_ as FBSYMBOL
 
 #ifndef ASTNODE_