[Bug target/42500] unnecessary register move

[carrot at google dot com]

--- Comment #3 from carrot at google dot com  2009-12-30 06:46 ---
My complete command line:

"/home/carrot/compiler/armobj/gcc/cc1plus" "-fpreprocessed" "testH.ii" "-quiet"
"-dumpbase" "testH.cpp" "-auxbase-strip" "obj/./testH.o" "-Os" "-o" "testH.s"

Please compile it as C++ program. When I compiled it as C program, I got the
same result as yours.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42500

[Bug target/42500] unnecessary register move

[ramana at gcc dot gnu dot org]

--- Comment #2 from ramana at gcc dot gnu dot org  2009-12-30 00:10 ---
(In reply to comment #1)
> What architecture options are you using  ? With .ident  "GCC: (GNU)
> 4.5.0 20091229 (experimental)" and -O2 I get the redundant move into r4 of sp 
> . 
> 
> But for -Os I get the following very different code.  I don't see the call to
> memset ever. \

Sorry I meant this rather than the code in comment #1

bar:
@ args = 0, pretend = 0, frame = 16
@ frame_needed = 0, uses_anonymous_args = 0
stmfd   sp!, {r0, r1, r2, r3, r4, lr}
str r0, [sp, #0]
mov r0, sp
stmib   sp, {r1, r2, r3}@ phole stm
bl  foo
mov r0, sp
mov r4, sp
bl  foo
ldmfd   sp!, {r0, r1, r2, r3, r4, pc}
.size   bar, .-bar
.ident  "GCC: (GNU) 4.5.0 20091229 (experimental)"
.section.note.GNU-stack,"",%progbits


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42500

[Bug target/42500] unnecessary register move

[ramana at gcc dot gnu dot org]

--- Comment #1 from ramana at gcc dot gnu dot org  2009-12-30 00:08 ---
What architecture options are you using  ? With .ident  "GCC: (GNU)
4.5.0 20091229 (experimental)" and -O2 I get the redundant move into r4 of sp . 

But for -Os I get the following very different code.  I don't see the call to
memset ever. 

.text
.align  2
.global foo
.type   foo, %function
foo:
@ args = 0, pretend = 0, frame = 0
@ frame_needed = 0, uses_anonymous_args = 0
stmfd   sp!, {r0, r1, r2, lr}   @,
mov r3, r0  @ a, a
ldr r2, [r0, #12]   @ tmp142,
str r2, [sp, #0]@ tmp142,
ldr r0, .L2 @,
ldmia   r3, {r1, r2, r3}@ phole ldm
bl  printf  @
ldmfd   sp!, {r1, r2, r3, pc}
.L3:
.align  2
.L2:
.word   .LC0
.size   foo, .-foo
.section.rodata.str1.1,"aMS",%progbits,1
.LC0:
.ascii  "%d %d %d %d \012\000"
.ident  "GCC: (GNU) 4.5.0 20091229 (experimental)"
.section.note.GNU-stack,"",%progbits


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ramana at gcc dot gnu dot org changed:

   What|Removed |Added

Summary|unnecessary register move   |unnecessary register move


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42500