CODEWITHSUNDEEP
c++c++11gcc
D.Brandyberry
D.Brandyberry

Reputation: 31

Assembler Messages: no such instruction when Compiling C++

I am attempting to compile a C++ code using gcc/5.3 on Scientific Linux release 6.7. I keep getting the following errors whenever I run my Makefile though:

/tmp/ccjZqIED.s: Assembler messages:
/tmp/ccjZqIED.s:768: Error: no such instruction: `shlx %rax,%rdx,%rdx'
/tmp/ccjZqIED.s:1067: Error: no such instruction: `shlx %rax,%rdx,%rdx'
/tmp/ccjZqIED.s: Assembler messages:
/tmp/ccjZqIED.s:6229: Error: no such instruction: `mulx %r10,%rcx,%rbx'
/tmp/ccjZqIED.s:6248: Error: no such instruction: `mulx %r13,%rcx,%rbx'
/tmp/ccjZqIED.s:7109: Error: no such instruction: `mulx %r10,%rcx,%rbx'
/tmp/ccjZqIED.s:7128: Error: no such instruction: `mulx %r13,%rcx,%rbx'

I've attmpted to follow the advice from this question with no change to my output: Compile errors with Assembler messages

My compiler options are currently:

CXXFLAGS        = -g -Wall -O0 -pg -std=c++11

Does anyone have any idea what could be causing this?

Upvotes: 3

Views: 23002

Answers (2)

Mikhail T.
Mikhail T.

Reputation: 3997

@jonathan-wakely's answer is correct in that the assembler, which your compiler invokes, does not understand the assembly code, which your compiler generates.

As to why that happens, there are multiple possibilities:

  1. You installed the newer compiler by hand without also updating your assembler
  2. Your compiler generates 64-bit instructions, but assembler is limited to 32-bit ones for some reason

Disabling AVX (-mno-avx) is unlikely to help, because it is not explicitly requested either -- there is no -march in the quoted CXXFLAGS. If it did help, then you did not show us all of the compiler flags -- it would've been best, if you simply included the entire compiler command-line.

If my suspicion is correct in 1. above, then you should build and/or install the latest binutils package, which will provide as aware of AVX instructions, among other things. You would then need to rebuild the compiler with the --with-as=/path/to/the/updated/as flag passed to configure.

If your Linux installation is 32-bit only (suspicion 2.), then you should not be generating 64-bit binaries at all. It is possible, but not trivial...

Do post the output of uname -a and your entire compiler command-line leading to the above error-messages.

Upvotes: 6

Jonathan Wakely
Jonathan Wakely

Reputation: 171333

This means that GCC is outputting an instruction that your assembler doesn't support. Either that's coming from inline asm in the source code, or that shouldn't happen, and suggests that you have compiled GCC on a different machine with a newer assembler, then copied it to another machine where it doesn't work properly.

Assuming those instructions aren't used explicitly in an asm statement you should be able to tell GCC not to emit those instructions with a suitable flag such as -mno-avx (or whatever flag is appropriate to disable use of those particular instructions).

Upvotes: 6

Related Questions