[Bug c/13984] New: Bad code generated with -O0

[Bug c/13984] New: Bad code generated with -O0

[klawson at ad-holdings dot co dot uk]

The following code was generated by sh-elf-gcc. The space variable (a long) is
taken from @(0,r3) and stored in r1. The len variable is taken from @(4.r3) and
stored in r3. A subtract operation is then performed, and r3 is used to find
where to store the result. This is bad because r3 was used as temporary storage
for the subtract operation and no longer contains a reference to memory. The
final mov.l instruction causes a fault as it is storing to a misaligned
(nonsense) address.

	576				space -= len;
-	0x8c0bb984	<cyg_sosend+2148>:		mov	#64,r3
-	0x8c0bb986	<cyg_sosend+2150>:		add	r14,r3
-	0x8c0bb988	<cyg_sosend+2152>:		mov	#64,r3
-	0x8c0bb98a	<cyg_sosend+2154>:		add	r14,r3
-	0x8c0bb98c	<cyg_sosend+2156>:		mov.l	@(0,r3),r1
-	0x8c0bb98e	<cyg_sosend+2158>:		mov.l	@(4,r3),r3
-	0x8c0bb990	<cyg_sosend+2160>:		sub	r3,r1
-	0x8c0bb992	<cyg_sosend+2162>:		mov.l	r1,@(0,r3)

The following CFLAGS are used:
-mb -m3 -Wall -Wpointer-arith -Wstrict-prototypes -Winline -Wundef
-Woverloaded-virtual -ggdb -O0 -ffunction-sections -fdata-sections -fno-rtti
-fno-exceptions -fvtable-gc -finit-priority

Using optimisation level 1, the code is generated as:
	576				space -= len;
-	0x8c0a6080	<cyg_sosend+1280>:		sub	r8,r11

-- 
           Summary: Bad code generated with -O0
           Product: gcc
           Version: 3.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: klawson at ad-holdings dot co dot uk
                CC: gcc-bugs at gcc dot gnu dot org
  GCC host triplet: i686-pc-cygwin
GCC target triplet: sh-elf-gcc


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13984

[Bug c/13984] Bad code generated with -O0

[klawson at ad-holdings dot co dot uk]

------- Additional Comments From klawson at ad-holdings dot co dot uk  2004-02-02 17:40 -------
Created an attachment (id=5652)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=5652&action=view)
Result of -save-temps


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13984

[Bug c/13984] sh-elf-gcc: Bad code generated with -O0

[klawson at ad-holdings dot co dot uk]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Bad code generated with -O0 |sh-elf-gcc: Bad code
                   |                            |generated with -O0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13984

[Bug target/13984] sh-elf-gcc: Bad code generated with -O0

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-02-02 17:52 -------
Can you try on a more recent compiler like 3.3.2?

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c                           |target
           Keywords|                            |wrong-code


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13984

[Bug target/13984] sh-elf-gcc: Bad code generated with -O0

[klawson at ad-holdings dot co dot uk]

------- Additional Comments From klawson at ad-holdings dot co dot uk  2004-02-04 15:58 -------
Subject: Re:  sh-elf-gcc: Bad code generated with -O0

Thanks. I tried compiling with 3.3.2 and the problem has disappeared. 
The code generated at -O0 and -O2 is now exactly the same for this bit 
of C, and is working in both cases.

Many thanks,
Kelvin.


pinskia at gcc dot gnu dot org wrote:

> ------- Additional Comments From pinskia at gcc dot gnu dot org  2004-02-02 17:52 -------
> Can you try on a more recent compiler like 3.3.2?
> 



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13984

[Bug target/13984] sh-elf-gcc: Bad code generated with -O0

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-02-04 16:10 -------
Submiter reports this works correctly with a new compiler so closing.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |3.3.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13984