[Bug modula2/115823] New: Wrong expansion of isnormal optab

[stefansf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115823

            Bug ID: 115823
           Summary: Wrong expansion of isnormal optab
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: modula2
          Assignee: gaius at gcc dot gnu.org
          Reporter: stefansf at gcc dot gnu.org
  Target Milestone: ---

Implementing isnormal optab for s390 results in

FAIL: gm2/builtins/run/pass/testisnormal.mod compilation,  -O
FAIL: gm2/builtins/run/pass/testisnormal.mod compilation,  -O -g
FAIL: gm2/builtins/run/pass/testisnormal.mod compilation,  -O3
-fomit-frame-pointer
FAIL: gm2/builtins/run/pass/testisnormal.mod compilation,  -O3
-fomit-frame-pointer -finline-functions
FAIL: gm2/builtins/run/pass/testisnormal.mod compilation,  -Os
FAIL: gm2/builtins/run/pass/testisnormal.mod compilation,  -g
UNRESOLVED: gm2/builtins/run/pass/testisnormal.mod execution,  -O  (link
failed)
UNRESOLVED: gm2/builtins/run/pass/testisnormal.mod execution,  -O -g  (link
failed)
UNRESOLVED: gm2/builtins/run/pass/testisnormal.mod execution,  -O3
-fomit-frame-pointer  (link failed)
UNRESOLVED: gm2/builtins/run/pass/testisnormal.mod execution,  -O3
-fomit-frame-pointer -finline-functions  (link failed)
UNRESOLVED: gm2/builtins/run/pass/testisnormal.mod execution,  -Os  (link
failed)
UNRESOLVED: gm2/builtins/run/pass/testisnormal.mod execution,  -g  (link
failed)

All tests output

/usr/bin/ld: /tmp/ccFZtxN6.o: in function `test':
testisnormal.mod:(.text+0x2d4): undefined reference to `__builtin_isnormal'
collect2: error: ld returned 1 exit status

In math.h we have

#  define isnormal(x) __builtin_isnormal (x)

which means for C code in expand_builtin

  if (!optimize
      && !called_as_built_in (fndecl)
      && fcode != BUILT_IN_FORK
      && fcode != BUILT_IN_EXECL
      && fcode != BUILT_IN_EXECV
      && fcode != BUILT_IN_EXECLP
      && fcode != BUILT_IN_EXECLE
      && fcode != BUILT_IN_EXECVP
      && fcode != BUILT_IN_EXECVE
      && fcode != BUILT_IN_CLEAR_CACHE
      && !ALLOCA_FUNCTION_CODE_P (fcode)
      && fcode != BUILT_IN_FREE
      && (fcode != BUILT_IN_MEMSET
          || !(flag_inline_stringops & ILSOP_MEMSET))
      && (fcode != BUILT_IN_MEMCPY
          || !(flag_inline_stringops & ILSOP_MEMCPY))
      && (fcode != BUILT_IN_MEMMOVE
          || !(flag_inline_stringops & ILSOP_MEMMOVE))
      && (fcode != BUILT_IN_MEMCMP
          || !(flag_inline_stringops & ILSOP_MEMCMP)))
    return expand_call (exp, target, ignore);

`called_as_built_in (fndecl)` is always true whereas for gm2 it evaluates to
false due to the call side being

  isnormal (1.0e+0)

However, in rtx_for_function_call the symbol reference

  funexp = XEXP (DECL_RTL (fndecl), 0);

is actually __builtin_isnormal which leads to a linker error.

Out of curiosity, the test output indicates that this error also happens e.g.
for -O3.  However, looking into the logs, those tests where never executed with
-O3.  Kinda surprised me.