Hi, the following patch adjusts used registers for thiscall-calling convention thunks, so that there aren't register-collisions. Issue was that thiscall-convention has different register-usage as regparam, but it wasn't handled.
ChangeLog 2012-11-25 Kai Tietz PR target/55171 * i386.c (get_scratch_register_on_entry): Handle thiscall-convention. (split_stack_prologue_scratch_regno): Likewise. (ix86_static_chain): Likewise. (x86_output_mi_thunk): Likewise. Test on i686-w64-mingw32. Ok for apply? Regards, Kai --- i386.c 2012-11-24 21:34:57.686148400 +0100 +++ i386.c2 2012-11-24 21:34:42.370272400 +0100 @@ -9655,6 +9655,8 @@ get_scratch_register_on_entry (struct sc tree decl = current_function_decl, fntype = TREE_TYPE (decl); bool fastcall_p = lookup_attribute ("fastcall", TYPE_ATTRIBUTES (fntype)) != NULL_TREE; + bool thiscall_p + = lookup_attribute ("thiscall", TYPE_ATTRIBUTES (fntype)) != NULL_TREE; bool static_chain_p = DECL_STATIC_CHAIN (decl); int regparm = ix86_function_regparm (fntype, decl); int drap_regno @@ -9665,10 +9667,17 @@ get_scratch_register_on_entry (struct sc if ((regparm < 1 || (fastcall_p && !static_chain_p)) && drap_regno != AX_REG) regno = AX_REG; - else if (regparm < 2 && drap_regno != DX_REG) + /* 'thiscall' sets regparm to 1, uses ecx for arguments and edx + for the static chain register. */ + else if (thiscall_p && !static_chain_p) + regno = drap_regno != DX_REG ? DX_REG : AX_REG; + else if (thiscall_p && static_chain_p && drap_regno != AX_REG) + regno = AX_REG; + else if (regparm < 2 && !thiscall_p && drap_regno != DX_REG) regno = DX_REG; /* ecx is the static chain register. */ - else if (regparm < 3 && !fastcall_p && !static_chain_p + else if (regparm < 3 && !fastcall_p && !thiscall_p + && !static_chain_p && drap_regno != CX_REG) regno = CX_REG; else if (ix86_save_reg (BX_REG, true)) @@ -11180,12 +11189,15 @@ split_stack_prologue_scratch_regno (void return R11_REG; else { - bool is_fastcall; + bool is_fastcall, is_thiscall; int regparm; is_fastcall = (lookup_attribute ("fastcall", TYPE_ATTRIBUTES (TREE_TYPE (cfun->decl))) != NULL); + is_thiscall = (lookup_attribute ("thiscall", + TYPE_ATTRIBUTES (TREE_TYPE (cfun->decl))) + != NULL); regparm = ix86_function_regparm (TREE_TYPE (cfun->decl), cfun->decl); if (is_fastcall) @@ -11198,6 +11210,12 @@ split_stack_prologue_scratch_regno (void } return AX_REG; } + else if (is_thiscall) + { + if (!DECL_STATIC_CHAIN (cfun->decl)) + return DX_REG; + return AX_REG; + } else if (regparm < 3) { if (!DECL_STATIC_CHAIN (cfun->decl)) @@ -25134,7 +25152,7 @@ ix86_static_chain (const_tree fndecl, bo fntype = TREE_TYPE (fndecl); ccvt = ix86_get_callcvt (fntype); - if ((ccvt & (IX86_CALLCVT_FASTCALL | IX86_CALLCVT_THISCALL)) != 0) + if ((ccvt & IX86_CALLCVT_FASTCALL) != 0) { /* Fastcall functions use ecx/edx for arguments, which leaves us with EAX for the static chain. @@ -25142,6 +25160,12 @@ ix86_static_chain (const_tree fndecl, bo leaves us with EAX for the static chain. */ regno = AX_REG; } + else if ((ccvt & IX86_CALLCVT_THISCALL) != 0) + { + /* Thiscall functions use ecx for arguments, which leaves + us with EDX for the static chain. */ + regno = DX_REG; + } else if (ix86_function_regparm (fntype, fndecl) == 3) { /* For regparm 3, we have no free call-clobbered registers in @@ -34799,8 +34823,10 @@ x86_output_mi_thunk (FILE *file, else { unsigned int ccvt = ix86_get_callcvt (TREE_TYPE (function)); - if ((ccvt & (IX86_CALLCVT_FASTCALL | IX86_CALLCVT_THISCALL)) != 0) + if ((ccvt & IX86_CALLCVT_FASTCALL) != 0) tmp_regno = AX_REG; + else if ((ccvt & IX86_CALLCVT_THISCALL) != 0) + tmp_regno = DX_REG; else tmp_regno = CX_REG; }