On Wed, Nov 20, 2013 at 1:32 PM, Ilya Enkovich <enkovich....@gmail.com> wrote:
>> >> > Here is a patch to add size relocation and instruction to obtain
>> >> > object's size in i386 target.
>> >>
>> >> +(define_insn "move_size_reloc_<mode>"
>> >> + [(set (match_operand:SWI48 0 "register_operand" "=r")
>> >> + (match_operand:<MODE> 1 "size_relocation" "Z"))]
>> >> + ""
>> >> +{
>> >> + return "mov{<imodesuffix>}\t{%1, %0|%0, %1}";
>> >>
>> >> Please don't change x86_64_immediate_operand just to use "Z"
>> >> constraint The predicate is used in a couple of other places that for
>> >> sure don't accept your change.
>> >>
>> >> Better write this insn in an explicit way (see for example
>> >> tls_initial_exec_64_sun). Something like:
>> >>
>> >> (define_insn "move_size_reloc_<mode>"
>> >> [(set (match_operand:SWI48 0 "register_operand" "=r")
>> >> (unspec:SWI48
>> >> [(match_operand 1 "symbolic_operand" "..." )]
>> >> UNSPEC_SIZEOF))]
>> >> ""
>> >> "mov{<imodesuffix>}\t{%a1@SIZE, %0|%0, %a1@SIZE}")
>> >>
>> >> You will probably need to define new operand 1 predicate and constraint.
>> >>
>> >> Uros.
>> >
>> > Hi, Uros! Thanks for comments! Here is what I got trying to follow your
>> > suggestion. Does it look better?
>>
>> You actually don't need any operand modifiers in the insn template. Simply
>> use:
>>
>> "mov{<imodesuffix>}\t{%1@SIZE, %0|%0, %1@SIZE}"
>>
>> and you will automatically get
>>
>> "movl $zzz, %eax" or "mov %eax, OFFSET FLAT: zzz".
>>
>> Since your pattern allows only symbolic_operand, there is no reload,
>> so you can avoid the constraint alltogether.
>>
>> BTW: Did you consider various -mcmodel=... options? For DImode moves,
>> you should check x86_64_zext_immediate_operand predicate and output
>> either "movl $zzz, %eax" or "movabs $zzz, %rax". There is no movq with
>> 64bit immediate. Please see movdi pattern.
>
> Yep, for large objects it may work wrongly. Does anyone use static objects
> >4Gb? :)
>
> Large address does not mean large object but seems we have to be conservative
> here. I added x86_64_zext_immediate_operand check with additional CM_KERNEL
> check because in this model object size should always fit 32 bits.
IMO, we should list code models that support object sizes > 31bits for
64bit target. The object size in small models will never be > 31bits
(and never negative), so we can use movl unconditionally.
Please try attached patch.
Uros.
Index: i386.md
===================================================================
--- i386.md (revision 205051)
+++ i386.md (working copy)
@@ -79,6 +79,7 @@
UNSPEC_PLTOFF
UNSPEC_MACHOPIC_OFFSET
UNSPEC_PCREL
+ UNSPEC_SIZEOF
;; Prologue support
UNSPEC_STACK_ALLOC
@@ -18458,6 +18459,30 @@
"bndstx\t{%2, %3|%3, %2}"
[(set_attr "type" "mpxst")])
+(define_insn "move_size_reloc_si"
+ [(set (match_operand:SI 0 "register_operand" "=r")
+ (unspec:SI
+ [(match_operand:SI 1 "symbol_operand")]
+ UNSPEC_SIZEOF))]
+ "TARGET_MPX"
+ "mov{l}\t{%1@SIZE, %0|%0, %1@SIZE}"
+ [(set_attr "type" "imov")])
+
+(define_insn "move_size_reloc_di"
+ [(set (match_operand:DI 0 "register_operand" "=r")
+ (unspec:DI
+ [(match_operand:DI 1 "symbol_operand")]
+ UNSPEC_SIZEOF))]
+ "TARGET_64BIT && TARGET_MPX"
+{
+ if (ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_LARGE
+ || ix86_cmodel == CM_MEDIUM_PIC || ix86_cmodel == CM_LARGE_PIC)
+ return "movabs{q}\t{%1@SIZE, %0|%0, %1@SIZE}";
+ else
+ return "mov{l}\t{%1@SIZE, %k0|%k0, %1@SIZE}";
+}
+ [(set_attr "type" "imov")])
+
(include "mmx.md")
(include "sse.md")
(include "sync.md")
Index: predicates.md
===================================================================
--- predicates.md (revision 205051)
+++ predicates.md (working copy)
@@ -119,6 +119,10 @@
(match_test "TARGET_64BIT")
(match_test "REGNO (op) > BX_REG")))
+;; Return true if VALUE is a symbol reference
+(define_predicate "symbol_operand"
+ (match_code "symbol_ref"))
+
;; Return true if VALUE can be stored in a sign extended immediate field.
(define_predicate "x86_64_immediate_operand"
(match_code "const_int,symbol_ref,label_ref,const")
