Re: [PATCH] powerpc/math-emu: Fix building with clang

On Sat, 3 Nov 2018 at 03:24, Nick Desaulniers [off-list ref] wrote:

On Thu, Nov 1, 2018 at 8:37 PM Joel Stanley [off-list ref] wrote:

quoted

  make CC=clang-8 ARCH=powerpc CROSS_COMPILE=powerpc-linux-gnu-  ppc44x_defconfig
  make CC=clang-8 ARCH=powerpc CROSS_COMPILE=powerpc-linux-gnu-

  ...

  arch/powerpc/math-emu/fnmsub.c:46:2: error: invalid use of a cast in a
  inline asm context requiring an l-value: remove the cast or build with
  -fheinous-gnu-extensions
          FP_ADD_D(R, T, B);
          ^~~~~~~~~~~~~~~~~
  ./include/math-emu/double.h:110:27: note: expanded from macro 'FP_ADD_D'
  #define FP_ADD_D(R,X,Y)                 _FP_ADD(D,2,R,X,Y)
                                          ^~~~~~~~~~~~~~~~~~
  ./include/math-emu/op-common.h:367:34: note: expanded from macro '_FP_ADD'
  #define _FP_ADD(fs, wc, R, X, Y) _FP_ADD_INTERNAL(fs, wc, R, X, Y, '+')
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  ./include/math-emu/op-common.h:264:4: note: expanded from macro '_FP_ADD_INTERNAL'
            _FP_FRAC_ADD_##wc(R, X, Y);                                        \
            ^~~~~~~~~~~~~~~~~~~~~~~~~~
  note: (skipping 1 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)

^^^ Hi Joel, would you mind recompiling with
`-fmacro-backtrace-limit=0` hacked in and including the full
backtrace?  I'm curious if there's a more appropriate fix, but can't
tell where the inline asm is that clang is complaining about.

Sure. Here's the full backtrace:

arch/powerpc/math-emu/fnmsub.c:46:2: error: invalid use of a cast in a
inline asm context requiring an l-value: remove
      the cast or build with -fheinous-gnu-extensions
        FP_ADD_D(R, T, B);
        ^~~~~~~~~~~~~~~~~
./include/math-emu/double.h:110:27: note: expanded from macro 'FP_ADD_D'
#define FP_ADD_D(R,X,Y)                 _FP_ADD(D,2,R,X,Y)
                                        ^~~~~~~~~~~~~~~~~~
./include/math-emu/op-common.h:367:34: note: expanded from macro '_FP_ADD'
#define _FP_ADD(fs, wc, R, X, Y) _FP_ADD_INTERNAL(fs, wc, R, X, Y, '+')
                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/math-emu/op-common.h:274:4: note: expanded from macro
'_FP_ADD_INTERNAL'
          _FP_FRAC_SUB_##wc(R, X, Y);                                        \
          ^~~~~~~~~~~~~~~~~~~~~~~~~~
<scratch space>:268:1: note: expanded from here
_FP_FRAC_SUB_2
^
./include/math-emu/op-2.h:97:19: note: expanded from macro '_FP_FRAC_SUB_2'
  __FP_FRAC_SUB_2(R##_f1, R##_f0, X##_f1, X##_f0, Y##_f1, Y##_f0)
  ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<scratch space>:269:1: note: expanded from here
R_f1
^
./arch/powerpc/include/asm/sfp-machine.h:283:27: note: expanded from
macro 'sub_ddmmss'
               : "=r" ((USItype)(sh)),                                  \
                       ~~~~~~~~~~^~~