ARM compilation error, VFP registered used by exec

Question

I have been having this problem for the last few days and I can't get my head around what is really happening here, or what is the problem.

I have a makefile with these flags:

CC = arm-linux-gnueabihf-gcc-4.6
FLAGS = -O3 -march=armv7-a -mtune=cortex-a9 -mfpu=neon -ftree-vectorize -mfloat-abi=softfp -std=gnu99

I have a library in a .a file, which has some object files, all I need to do is link them in with my executable. I know the prototypes and all that, the only thing that complains is the following:

/usr/bin/ld: error: *EXECUTABLE* uses VFP register arguments, *OBJECTFILE* does not
/usr/bin/ld: failed to merge target specific data of file *OBJECTFILE*

When I don't use the -mfloat-abi=softfp, I get another error relating to floating point registers.

Does anyone have any idea what is causing this, and what I can do to fix this, such as making it so that my executable does not use Virtual Floating Point Register arguments?

x@x:~/Desktop/perf_test$ make
arm-linux-gnueabihf-gcc-4.6 -c -O3 -march=armv7-a -mtune=cortex-a9 -mfpu=neon -ftree-vectorize -std=gnu99 -mfloat-abi=softfp  perf_test.c ../baseline/util.c
arm-linux-gnueabihf-gcc-4.6 -o perf_test perf_test.o util.o  ../baseline/lib.a
/usr/bin/ld: error: perf_test uses VFP register arguments, perf_test.o does not
/usr/bin/ld: failed to merge target specific data of file perf_test.o
/usr/bin/ld: error: perf_test uses VFP register arguments, util.o does not
/usr/bin/ld: failed to merge target specific data of file util.o
/usr/bin/ld: error: perf_test uses VFP register arguments, ../baseline/lib.a(a.o) does not
/usr/bin/ld: failed to merge target specific data of file ../baseline/lib.a(a.o)
/usr/bin/ld: error: perf_test uses VFP register arguments, ../baseline/lib.a(b.o) does not
/usr/bin/ld: failed to merge target specific data of file ../baseline/lib.a(b.o)
/usr/bin/ld: error: perf_test uses VFP register arguments, ../baseline/lib.a(c.o) does not
/usr/bin/ld: failed to merge target specific data of file ../baseline/lib.a(c.o)
/usr/bin/ld: error: perf_test uses VFP register arguments, ../baseline/lib.a(d.o) does not
/usr/bin/ld: failed to merge target specific data of file ../baseline/lib.a(d.o)
/usr/bin/ld: error: perf_test uses VFP register arguments, ../baseline/lib.a(e.o) does not
/usr/bin/ld: failed to merge target specific data of file ../baseline/lib.a(e.o)
/usr/bin/ld: error: perf_test uses VFP register arguments, ../baseline/lib.a(f.o) does not
/usr/bin/ld: failed to merge target specific data of file ../baseline/lib.a(f.o)
collect2: ld returned 1 exit status
make: *** [perf_test] Error 1

Answer 1

I have found on an arm hardfloat system where glibc binutils and gcc were crosscompiled, using gcc gives the same error.

It is solved by exporting-mfloat-abi=hard to flags, then gcc compiles without errors.

Answer 2

In my case CFLAGS = -O0 -g -Wall -I. -mcpu=cortex-m4 -mthumb -mfpu=fpv4-sp-d16 -mfloat-abi=soft has helped. As you can see, i used it for my stm32f407.

Answer 3

In my particular case -g -march=armv7-a -mfloat-abi=hard -mfpu=neon -marm -mthumb-interwork worked.

Answer 4

I was facing the same issue. I was trying to build linux application for Cyclone V FPGA-SoC. I faced the problem as below:

Error: <application_name> uses VFP register arguments, main.o does not

I was using the toolchain arm-linux-gnueabihf-g++ provided by embedded software design tool of altera.

It is solved by exporting: mfloat-abi=hard to flags, then arm-linux-gnueabihf-g++ compiles without errors. Also include the flags in both CC & LD.

Answer 5

I encountered the issue using Atollic for ARM on STM32F4 (I guess it applies to all STM32 with FPU).

Using SW floating point didn't worked well for me (thus compiling correctly).

When STM32cubeMX generates code for TrueStudio (Atollic), it doesn't set an FPU unit in C/C++ build settings (not sure about generated code for other IDEs).

Set a FPU in "Target" for (under project Properties build settings):

• Assembler
• C Compiler
• C Linker

Then you have the choice to Mix HW/SW fp or use HW.

Generated command lines are added with this for the intended target:

-mfloat-abi=hard -mfpu=fpv4-sp-d16

armatollic

Answer 6

This is guesswork, but you may need to supply some or all of the floating point related switches for the link stage as well.