[PATCH] D28516: [ELF] - Explicitly list supported relocations for x86 target.

[Rafael Avila de Espindola via llvm-commits]

LGTM

George Rimar via Phabricator <reviews at reviews.llvm.org> writes:

> grimar created this revision.
> grimar added reviewers: ruiu, rafael.
> grimar added subscribers: llvm-commits, grimar, evgeny777.
>
> Previously some value was returned by default for relocations by getRelExpr(),
> even if relocation actually was not supported.
>
> This is orthogonal alternative to https://reviews.llvm.org/D28094.
> Instead of implementing probably useless R_386_PC8/R_386_8 relocations,
> this patch uses them in a testcase to demonstrate what happens
> when LLD mets unsupported relocations.
>
> Patch passes all testcases and changes logic only for x86.
> Patches for other targets can be posted separatelly.
>
>
> https://reviews.llvm.org/D28516
>
> Files:
>   ELF/Target.cpp
>   test/ELF/Inputs/unknown-reloc.s
>   test/ELF/unknown-reloc.s
>
>
> Index: test/ELF/unknown-reloc.s
> ===================================================================
> --- test/ELF/unknown-reloc.s
> +++ test/ELF/unknown-reloc.s
> @@ -0,0 +1,14 @@
> +# REQUIRES: x86
> +# RUN: llvm-mc -filetype=obj -triple=i386-pc-linux-gnu %s -o %t1.o
> +# RUN: llvm-mc -filetype=obj -triple=i386-pc-linux-gnu %S/Inputs/unknown-reloc.s -o %t2.o
> +# RUN: not ld.lld %t1.o %t2.o -o %t.out 2>&1 | FileCheck %s
> +
> +# CHECK: do not know how to handle relocation R_386_PC8(23)
> +# CHECK: do not know how to handle relocation R_386_8(22)
> +
> +.text
> +.global foo
> +foo:
> +
> +.byte und-foo
> +.byte foo
> Index: test/ELF/Inputs/unknown-reloc.s
> ===================================================================
> --- test/ELF/Inputs/unknown-reloc.s
> +++ test/ELF/Inputs/unknown-reloc.s
> @@ -0,0 +1,2 @@
> +.global und
> +und:
> Index: ELF/Target.cpp
> ===================================================================
> --- ELF/Target.cpp
> +++ ELF/Target.cpp
> @@ -356,7 +356,9 @@
>  
>  RelExpr X86TargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
>    switch (Type) {
> -  default:
> +  case R_386_16:
> +  case R_386_32:
> +  case R_386_TLS_LDO_32:
>      return R_ABS;
>    case R_386_TLS_GD:
>      return R_TLSGD;
> @@ -381,6 +383,10 @@
>      return R_TLS;
>    case R_386_TLS_LE_32:
>      return R_NEG_TLS;
> +  default:
> +    error("do not know how to handle relocation " + toString(Type) + "(" +
> +          Twine(Type) + ")");
> +    return R_HINT;
>    }
>  }
>  
>
>
> Index: test/ELF/unknown-reloc.s
> ===================================================================
> --- test/ELF/unknown-reloc.s
> +++ test/ELF/unknown-reloc.s
> @@ -0,0 +1,14 @@
> +# REQUIRES: x86
> +# RUN: llvm-mc -filetype=obj -triple=i386-pc-linux-gnu %s -o %t1.o
> +# RUN: llvm-mc -filetype=obj -triple=i386-pc-linux-gnu %S/Inputs/unknown-reloc.s -o %t2.o
> +# RUN: not ld.lld %t1.o %t2.o -o %t.out 2>&1 | FileCheck %s
> +
> +# CHECK: do not know how to handle relocation R_386_PC8(23)
> +# CHECK: do not know how to handle relocation R_386_8(22)
> +
> +.text
> +.global foo
> +foo:
> +
> +.byte und-foo
> +.byte foo
> Index: test/ELF/Inputs/unknown-reloc.s
> ===================================================================
> --- test/ELF/Inputs/unknown-reloc.s
> +++ test/ELF/Inputs/unknown-reloc.s
> @@ -0,0 +1,2 @@
> +.global und
> +und:
> Index: ELF/Target.cpp
> ===================================================================
> --- ELF/Target.cpp
> +++ ELF/Target.cpp
> @@ -356,7 +356,9 @@
>  
>  RelExpr X86TargetInfo::getRelExpr(uint32_t Type, const SymbolBody &S) const {
>    switch (Type) {
> -  default:
> +  case R_386_16:
> +  case R_386_32:
> +  case R_386_TLS_LDO_32:
>      return R_ABS;
>    case R_386_TLS_GD:
>      return R_TLSGD;
> @@ -381,6 +383,10 @@
>      return R_TLS;
>    case R_386_TLS_LE_32:
>      return R_NEG_TLS;
> +  default:
> +    error("do not know how to handle relocation " + toString(Type) + "(" +
> +          Twine(Type) + ")");
> +    return R_HINT;
>    }
>  }
>