https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69047
Bug ID: 69047
Summary: memcpy of 64-bit integer to 32-bit integer causes
pointless stack operations on ARM
Product: gcc
Version: 5.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: x.fix at o2 dot pl
Target Milestone: ---
Created attachment 37131
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37131&action=edit
d.c
When a function does memcpy to a local integer and returns it, pointless stack
operations are done (subtraction, and addition just after that).
Command line
============
arm-none-eabi-gcc -O3 -S -o- d.c
Output
======
Assembly code containing following function.
f:
@ Function supports interworking.
@ args = 0, pretend = 0, frame = 8
@ frame_needed = 0, uses_anonymous_args = 0
@ link register save eliminated.
sub sp, sp, #8
add sp, sp, #8
@ sp needed
bx lr
.size f, .-f
Version information
===================
Using built-in specs.
COLLECT_GCC=arm-none-eabi-gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/arm-none-eabi/5.3.0/lto-wrapper
Target: arm-none-eabi
Configured with: /build/arm-none-eabi-gcc/src/gcc-5.3.0/configure
--target=arm-none-eabi --prefix=/usr --with-sysroot=/usr/arm-none-eabi
--with-native-system-header-dir=/include --libexecdir=/usr/lib
--enable-languages=c,c++ --enable-plugins --disable-decimal-float
--disable-libffi --disable-libgomp --disable-libmudflap --disable-libquadmath
--disable-libssp --disable-libstdcxx-pch --disable-nls --disable-shared
--disable-threads --disable-tls --with-gnu-as --with-gnu-ld --with-system-zlib
--with-newlib --with-headers=/usr/arm-none-eabi/include
--with-python-dir=share/gcc-arm-none-eabi --with-gmp --with-mpfr --with-mpc
--with-isl --with-libelf --enable-gnu-indirect-function
--with-host-libstdcxx='-static-libgcc -Wl,-Bstatic,-lstdc++,-Bdynamic -lm'
--with-pkgversion='Arch Repository' --with-bugurl=https://bugs.archlinux.org/
--with-multilib-list=armv6-m,armv7-m,armv7e-m,armv7-r
Thread model: single
gcc version 5.3.0 (Arch Repository)
