[Bug target/81426] New: [SH]: unable to find a register to spill in class 'R0_REGS' when building webkit2gtk

["glaubitz at physik dot fu-berlin.de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81426

            Bug ID: 81426
           Summary: [SH]: unable to find a register to spill in class
                    'R0_REGS' when building webkit2gtk
           Product: gcc
           Version: 7.1.0
               URL: https://buildd.debian.org/status/fetch.php?pkg=webkit2
                    gtk&arch=sh4&ver=2.16.3-2&stamp=1496275824&raw=0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: glaubitz at physik dot fu-berlin.de
                CC: jrtc27 at jrtc27 dot com, kkojima at gcc dot gnu.org,
                    olegendo at gcc dot gnu.org
  Target Milestone: ---
            Target: sh*-*-*

Created attachment 41741
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41741&action=edit
Preprocessed source cc6kN21T.out (gzipped)

Trying to build webkit2gtk on Debian unstable sh4 with gcc-7.1.0 bails out
with:

/<<PKGBUILDDIR>>/Source/WTF/wtf/dtoa.cpp:1207:1: error: unable to find a
register to spill in class 'R0_REGS'
 }
 ^
/<<PKGBUILDDIR>>/Source/WTF/wtf/dtoa.cpp:1207:1: error: this is the insn:
(insn 1022 1021 1023 126 (parallel [
            (set (subreg:SI (reg:QI 2 r2 [1073]) 0)
                (unspec_volatile:SI [
                        (mem/v:QI (reg/f:SI 4 r4 [1069]) [-1  S1 A8])
                        (reg:QI 1072)
                        (reg:QI 7 r7 [1075])
                    ] UNSPECV_CMPXCHG_1))
            (set (mem/v:QI (reg/f:SI 4 r4 [1069]) [-1  S1 A8])
                (unspec_volatile:QI [
                        (const_int 0 [0])
                    ] UNSPECV_CMPXCHG_2))
            (set (reg:SI 147 t)
                (unspec_volatile:SI [
                        (const_int 0 [0])
                    ] UNSPECV_CMPXCHG_3))
            (clobber (scratch:SI))
            (clobber (reg:SI 0 r0))
            (clobber (reg:SI 1 r1))
        ]) /usr/include/c++/6/bits/atomic_base.h:434 664
{atomic_compare_and_swapqi_soft_gusa}
     (expr_list:REG_DEAD (reg:QI 7 r7 [1075])
        (expr_list:REG_DEAD (reg:QI 1072)
            (expr_list:REG_UNUSED (reg:SI 1 r1)
                (expr_list:REG_UNUSED (reg:SI 0 r0)
                    (nil))))))
/<<PKGBUILDDIR>>/Source/WTF/wtf/dtoa.cpp:1207: confused by earlier errors,
bailing out

Attaching pre-processed source.
(...)
Preprocessed source stored into /tmp/cc6kN21T.out file, please attach this to
your bugreport.