Hi, I've been porting gcc 4.2.0 to a new platform. But there is a very
odd problem when turning -O1 option (or higher level).
As my ISA supports only 13-bit immediate filed, the process of
assigning a value to register should be split into two stage.
(define_insn "movsi_high"
[(set (match_operand:SI 0 "register_operand" "=b")
(high:SI (match_operand:SI 1 "const_int_operand" "i")))]
""
"lih \t%0,%U1"
[(set_attr "type" "move")
(set_attr "slottable" "no")]
(define_insn "movsi_lo_sum"
[(set (match_operand:SI 0 "register_operand" "=b")
(lo_sum:SI (match_operand:SI 1 "register_operand" "b")
(match_operand:SI 2 "const_int_operand" "i")))]
""
"or \t%0,%1,%L2"
[(set_attr "type" "move")])
The normal pattern to assign values is
(define_insn "arch_movsi"
[(set (match_operand:SI 0 "nonimmediate_operand" "=b")
(match_operand:SI 1 "arch_move_operand" "i"))]
""
"@
li \t%0,%1\t\t # movsi: move symbol or label re si"
[(set_attr "type" "logic")
(set_attr "slottable" "yes")])
the operad predicate apc_move_operand assert the immediate value is only 13-bit.
(define_predicate "arch_move_operand"
(match_code "mem,reg,subreg,const_int,symbol_ref,label_ref,const")
{
... ...
case const_int:
return (INTVAL(op) >= -(1 << 13) && INTVAL(op) < (1 << 14));
...
}
But when I compile the following statement:
char* buf[20];
memcpy (&buf3[18], "ab", 2);
it generates insn before GREG (global register assignment) pass like
(insn 90 43 34 2 (set (reg:SI 58)
(high:SI (const_int 24930 [0x6162]))) 2 {movsi_high} (nil)
(expr_list:REG_EQUIV (high:SI (const_int 24930 [0x6162]))
;;0x6162 represents "ab"
(nil)))
which uses the correct pattern "movsi_high", but after GREG, the insn becomes
(insn 91 40 45 5 (set (reg:SI 27 r27 [orig:54+-2 ] [54])
(high:SI (const_int 24930 [0x6162]))) 4 {arch_movsi} (nil)
(nil)
which matches "arch_movsi" pattern, and thus 0x6162 is not qualified
for arch_move_operand, the final output is as follow:
"output_operand: invalid expression as operand"
Is there anybody helping me to figure out how the insn pattern is changing?
--
He Xiao
Shanghai Jiaotong University, 800 Dongchuang Road, Shanghai, China
