https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64037
H.J. Lu <hjl.tools at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |ebotcazou at gcc dot gnu.org --- Comment #10 from H.J. Lu <hjl.tools at gmail dot com> --- To pass enum class X : unsigned char { V = 2, }; assign_parm_setup_reg calls ix86_promote_function_mode (gdb) f 0 #0 ix86_promote_function_mode (type=0x7ffff19f85e8, mode=QImode, punsignedp=0x7fffffffd3c4, fntype=0x7ffff19f8738, for_return=2) at /export/gnu/import/git/gcc/gcc/config/i386/i386.c:8310 8310 if (type != NULL_TREE && POINTER_TYPE_P (type)) (gdb) call debug_tree (type) <enumeral_type 0x7ffff19f85e8 X type <integer_type 0x7ffff18a93f0 unsigned char public unsigned string-flag QI size <integer_cst 0x7ffff18a5fa8 constant 8> unit size <integer_cst 0x7ffff18a5fc0 constant 1> align 8 symtab 0 alias set -1 canonical type 0x7ffff18a93f0 precision 8 min <integer_cst 0x7ffff18a5fd8 0> max <integer_cst 0x7ffff18a5f78 255>> static unsigned type_5 QI size <integer_cst 0x7ffff18a5fa8 8> unit size <integer_cst 0x7ffff18a5fc0 1> align 8 symtab 0 alias set -1 canonical type 0x7ffff19f85e8 precision 8 min <integer_cst 0x7ffff18a5fd8 0> max <integer_cst 0x7ffff18a5f78 255> values <tree_list 0x7ffff19fb028 purpose <identifier_node 0x7ffff19f6738 V bindings <(nil)> local bindings <(nil)>> value <const_decl 0x7ffff18c21c0 V type <enumeral_type 0x7ffff19f85e8 X> readonly constant used VOID file pr64037.ii line 2 col 3 align 1 context <enumeral_type 0x7ffff19f85e8 X> initial <integer_cst 0x7ffff19d8d08 2>>> context <translation_unit_decl 0x7ffff7ff91e0 D.1> chain <type_decl 0x7ffff19f5c78 X>> (gdb) However, setup_incoming_promotions calls ix86_promote_function_mode with Breakpoint 18, ix86_promote_function_mode (type=0x7ffff18a9690, mode=SImode, punsignedp=0x7fffffffd774, fntype=0x7ffff19f8738, for_return=0) at /export/gnu/import/git/gcc/gcc/config/i386/i386.c:8310 8310 if (type != NULL_TREE && POINTER_TYPE_P (type)) (gdb) call debug_tree (type) <integer_type 0x7ffff18a9690 int public SI size <integer_cst 0x7ffff18a5e70 type <integer_type 0x7ffff18a9150 bitsizetype> constant 32> unit size <integer_cst 0x7ffff18a5e88 type <integer_type 0x7ffff18a90a8 sizetype> constant 4> align 32 symtab 0 alias set 1 canonical type 0x7ffff18a9690 precision 32 min <integer_cst 0x7ffff18c60c0 -2147483648> max <integer_cst 0x7ffff18c60d8 2147483647> pointer_to_this <pointer_type 0x7ffff18cb930>> (gdb) It uses a different type and mode. If I make this change to combine: diff --git a/gcc/combine.c b/gcc/combine.c index 1808f97..8bdfe2b 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -1562,7 +1562,7 @@ setup_incoming_promotions (rtx_insn *first) /* The mode and signedness of the argument as it is actually passed, after any TARGET_PROMOTE_FUNCTION_ARGS-driven ABI promotions. */ - mode3 = promote_function_mode (DECL_ARG_TYPE (arg), mode2, &uns3, + mode3 = promote_function_mode (DECL_ARG_TYPE (arg), mode1, &uns1, TREE_TYPE (cfun->decl), 0); to make setup_incoming_promotions consistent with assign_parm_setup_reg, the testcase works.