http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58361
Bug ID: 58361
Summary: Wrong floating point code generated for ARM target
Product: gcc
Version: 4.7.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: power at pobox dot sk
Created attachment 30765
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30765&action=edit
Preprocessed example code
Example code:
-------------
#include <math.h>
static const float LANCE_SPEED = 0.5f;
float posx = 0.0f, posy = 0.0f;
float _deg = 0.0f;
float test(int cnt) {
float sp;
if (cnt < 10)
sp = LANCE_SPEED * cnt / 10;
else
sp = LANCE_SPEED;
float degSin = sin(_deg);
float degCos = cos(_deg);
posx += degSin * sp;
posy += degCos * sp;
return sp;
}
-------------
Compiling the example code with parameters "-c -O2 -pipe -march=armv7-a
-mcpu=cortex-a8 -mtune=cortex-a8 -mfpu=vfpv3 -mfloat-abi=softfp" generates
wrong code for the case when the input parameter is 10 or more.
The preprocessed source is in the attachment.
The result of "objdump -S -r" is:
-------------
shot2.o: file format elf32-littlearm
Disassembly of section .text:
00000000 <test>:
0: e3500009 cmp r0, #9
4: e92d4010 push {r4, lr}
8: ed2d8b02 vpush {d8}
c: ceb68a00 vmovgt.f32 s16, #96 ; 0x60
10: e24dd008 sub sp, sp, #8
14: def27a04 vmovle.f32 s15, #36 ; 0x24
18: de080a10 vmovle s16, r0
1c: eeba8aef vcvt.f32.s32 s16, s16, #1
20: de888a27 vdivle.f32 s16, s16, s15
24: e59f403c ldr r4, [pc, #60] ; 68 <test+0x68>
28: e28d1004 add r1, sp, #4
2c: e1a0200d mov r2, sp
30: e5940000 ldr r0, [r4]
34: ebfffffe bl 0 <sincosf>
34: R_ARM_CALL sincosf
38: edd47a01 vldr s15, [r4, #4]
3c: ed947a02 vldr s14, [r4, #8]
40: eddd6a00 vldr s13, [sp]
44: ee067a88 vmla.f32 s14, s13, s16
48: eddd6a01 vldr s13, [sp, #4]
4c: ee180a10 vmov r0, s16
50: ee467a88 vmla.f32 s15, s13, s16
54: ed847a02 vstr s14, [r4, #8]
58: edc47a01 vstr s15, [r4, #4]
5c: e28dd008 add sp, sp, #8
60: ecbd8b02 vpop {d8}
64: e8bd8010 pop {r4, pc}
68: 00000000 .word 0x00000000
68: R_ARM_ABS32 .bss
-------------
The instruction at address c assigns the value 0.5f to register s16, and the
instruction at address 1c changes the value in register s16 (but it shouldn't,
in case r0 > 9).
I'm using a GCC crosscompiler for ARM linux (running on x64 linux) - gcc
version 4.7.3.
The result of "gcc -v" is:
-------------
Using built-in specs.
COLLECT_GCC=/opt/pandora/arm-2013.06.10/bin/pandora-gcc
COLLECT_LTO_WRAPPER=/opt/pandora/arm-2013.06.10/bin/../libexec/gcc/arm-cortex_a8-linux-gnueabi/4.7.3/lto-wrapper
Target: arm-cortex_a8-linux-gnueabi
Configured with: /home/roman/toolchain/.build/src/gcc-4.7.3/configure
--build=x86_64-build_unknown-linux-gnu --host=x86_64-build_unknown-linux-gnu
--target=arm-cortex_a8-linux-gnueabi
--prefix=/home/roman/x-tools/arm-cortex_a8-linux-gnueabi
--with-sysroot=/home/roman/x-tools/arm-cortex_a8-linux-gnueabi/arm-cortex_a8-linux-gnueabi/sysroot
--enable-languages=c,c++,d --with-arch=armv7-a --with-cpu=cortex-a8
--with-tune=cortex-a8 --with-fpu=vfpv3 --with-float=softfp
--with-pkgversion='crosstool-NG hg+unknown-20130627.210751'
--enable-__cxa_atexit --disable-libmudflap --disable-libgomp --disable-libssp
--disable-libquadmath --disable-libquadmath-support
--with-gmp=/home/roman/toolchain/.build/arm-cortex_a8-linux-gnueabi/buildtools
--with-mpfr=/home/roman/toolchain/.build/arm-cortex_a8-linux-gnueabi/buildtools
--with-mpc=/home/roman/toolchain/.build/arm-cortex_a8-linux-gnueabi/buildtools
--with-ppl=/home/roman/toolchain/.build/arm-cortex_a8-linux-gnueabi/buildtools
--with-cloog=/home/roman/toolchain/.build/arm-cortex_a8-linux-gnueabi/buildtools
--with-libelf=/home/roman/toolchain/.build/arm-cortex_a8-linux-gnueabi/buildtools
--with-host-libstdcxx='-static-libgcc -Wl,-Bstatic,-lstdc++,-Bdynamic -lm
-L/home/roman/toolchain/.build/arm-cortex_a8-linux-gnueabi/buildtools/lib
-lpwl' --enable-threads=posix --enable-target-optspace --disable-nls
--disable-multilib
--with-local-prefix=/home/roman/x-tools/arm-cortex_a8-linux-gnueabi/arm-cortex_a8-linux-gnueabi/sysroot
--enable-c99 --enable-long-long
Thread model: posix
gcc version 4.7.3 (crosstool-NG hg+unknown-20130627.210751)
-------------
