Hello,
I got some problems with the SPE-extensions. Quite a severe as I think.
For
float t;
char u;
t = 1.0;
u = ( ( t<0.0)?-1:((t>0.0)?1:0));
with the following compiler flags
-mcpu=8540 -meabi -mspe=yes -mabi=spe -mfloat-gprs=yes
-fsingle-precision-constant -fshort-double -mno-sdata -c -g -D__EMB_RPE__
the result for u is either -1 if t < 0.0 or 0 else. The case if t > 0.0 is
never taken. My diab shows correct results.
Generated assembler:
t = 1.0;
lis r0,0x3F80
stw r0,0x1EC(r31)
u = ( ( t<0.0)?-1:((t>0.0)?1:0));
lwz r9,0x1EC(r31)
li r0,0x0
efscmplt cr7,r9,r0
bgt cr7,0x39F04
b 0x39F10
li r0,-0x1
stb r0,0x1F1(r31)
b 0x39F28
lwz r9,0x1EC(r31)
li r0,0x0
efscmpgt cr7,r9,r0
mfcr r0
extrwi r0,r0,0x1,0x1E ; r0,r0,1,30
stb r0,0x1F1(r31)
lbz r0,0x1F1(r31)
stb r0,0x1F0(r31)
Looking in the e500-core-manual it shows that the GT-compare-result is stored
in bit 61 of CR. I suppose in this case the extrwi (or rlwinm-Instruction in
case of objdump) should check for bit 29 (=61-32), which is not the case.
Sincery yours,
Christian Metzler.
--
Summary: Wrong code generated with SPE-Extensions on PowerPC
Product: gcc
Version: 3.4.4
Status: UNCONFIRMED
Severity: critical
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: christian dot metzler at bmw-carit dot de
GCC host triplet: i686-pc-cygwin
GCC target triplet: powerpc-unknown-eabi
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26398
