[ELF] Delete R_PPC64_CALL_PLT from isRelExpr()

[MaskRay]

Summary

It was added by D46654 but is actually never used.
R_PPC64_CALL_PLT (was: R_PPC_CALL_PLT) is a static link-time constant.

[ruiu]

LGTM

Do you think you can add a test?

[MaskRay]

In D62994#1533651, @ruiu wrote:

LGTM

Do you think you can add a test?

I cannot. I think D46654 could just add R_PPC_CALL, not R_PPC_CALL_PLT. R_PPC64_CALL_PLT is similar to R_PLT_PC. Since R_PLT_PC is not in isRelExpr(), R_PPC64_CALL_PLT does not have to be in the list, either.

Before the control reaches isRelExpr(), R_PPC64_CALL has been precluded by:

static bool isStaticLinkTimeConstant(RelExpr E, RelType Type, const Symbol &Sym,

                                   InputSectionBase &S, uint64_t RelOff) {
// These expressions always compute a constant
if (oneof<R_DTPREL, R_GOTPLT, R_GOT_OFF, R_HEXAGON_GOT, R_TLSLD_GOT_OFF,
          R_MIPS_GOT_LOCAL_PAGE, R_MIPS_GOTREL, R_MIPS_GOT_OFF,
          R_MIPS_GOT_OFF32, R_MIPS_GOT_GP_PC, R_MIPS_TLSGD,
          R_AARCH64_GOT_PAGE_PC, R_GOT_PC, R_GOTONLY_PC, R_GOTPLTONLY_PC,
          R_PLT_PC, R_TLSGD_GOT, R_TLSGD_GOTPLT, R_TLSGD_PC, R_PPC32_PLTREL,
          R_PPC64_CALL_PLT, R_PPC64_RELAX_TOC, R_TLSDESC_CALL, R_TLSDESC_PC,
          R_AARCH64_TLSDESC_PAGE, R_HINT, R_TLSLD_HINT, R_TLSIE_HINT>(E))
  return true;

lld/trunk/ELF/Relocations.cpp

return oneof<R_GOT, R_GOT_OFF, R_HEXAGON_GOT, R_MIPS_GOT_LOCAL_PAGE,
                R_MIPS_GOT_OFF, R_MIPS_GOT_OFF32, R_AARCH64_GOT_PAGE_PC,
                R_GOT_PC, R_GOTPLT>(Expr);
 }
 
 // True if this expression is of the form Sym - X, where X is a position in the
 // file (PC, or GOT for example).
 static bool isRelExpr(RelExpr Expr) {
   return oneof<R_PC, R_GOTREL, R_GOTPLTREL, R_MIPS_GOTREL, R_PPC64_CALL,
-               R_PPC64_CALL_PLT, R_PPC64_RELAX_TOC, R_AARCH64_PAGE_PC,
-               R_RELAX_GOT_PC>(Expr);
+               R_PPC64_RELAX_TOC, R_AARCH64_PAGE_PC, R_RELAX_GOT_PC>(Expr);
 }
 
 // Returns true if a given relocation can be computed at link-time.
 //
 // For instance, we know the offset from a relocation to its target at
 // link-time if the relocation is PC-relative and refers a
 // non-interposable function in the same executable. This function
 // will return true for such relocation.