http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56833
Bug #: 56833
Summary: [4.9 Regression] Valid register is over written by
reload pass
Classification: Unclassified
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: vishnu....@atmel.com
AVR target built with specs:
Using built-in specs.
COLLECT_GCC=/home/vishnu.k_s/build-linux_x86_64/bldcc/gcc/xgcc
Target: avr
Configured with: ../gcc-trunk/configure
--prefix=/home/vishnu.k_s/build-linux_x86_64//install --target=avr
--enable-languages=c,c++ --disable-nls --with-gmp=/proj/install/gmp-4.3.2/
--with-mpfr=/proj/install/mpfr-2.4.2/ --with-mpc=/proj/install/mpc-0.8.2/
Thread model: single
gcc version 4.9.0 20130326 (experimental) (GCC)
Above compiler generate wrong code for testcase present in
gcc.c-torture/execute/simd-1.c.
gcc options : -O1 -mmcu=atmega1280
(snip of assembly)
ldi r30,lo8(res) ; r30/r31 is loaded with address of res
ldi r31,hi8(res) ;
st Z,r24
ldd r31,Y+1 ; Modifying r31 register
sts res+1,r31
sts res+2,r27
sts res+3,r26
sts res+4,r23
...
lds r22,res+4+2
lds r23,res+4+3
ld r24,Z ; regsiter pair r30/r31 is used to load from res
ldd r25,Z+1
ldd r26,Z+2
ldd r27,Z+3
(snip of assembly)
It looks like r31 is corrupted after reload pass.
