[PATCH] D65032: [ELF] Support explicitly overriding relocation model in LTO

[Petr Hosek via Phabricator via llvm-commits]

phosek created this revision.
phosek added a reviewer: pcc.
Herald added subscribers: llvm-commits, dexonsmith, steven_wu, MaskRay, arichardson, inglorion, emaste.
Herald added a reviewer: espindola.
Herald added a project: LLVM.

lld currently selects the relocation model automatically depending on
the link flags specified, but in some cases it'd be useful to allow
explicitly overriding the relocation model using a flag.


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D65032

Files:
  lld/Common/TargetOptionsCommandFlags.cpp
  lld/ELF/LTO.cpp
  lld/include/lld/Common/TargetOptionsCommandFlags.h
  lld/test/ELF/lto/relocation-model.ll


Index: lld/test/ELF/lto/relocation-model.ll
===================================================================
--- lld/test/ELF/lto/relocation-model.ll
+++ lld/test/ELF/lto/relocation-model.ll
@@ -33,6 +33,15 @@
 ; RUN: llvm-readobj -r %t-out.lto.o | FileCheck %s --check-prefix=PIC
 
 
+;; Explicit flag.
+
+; RUN: ld.lld %t.o -o %t-out -save-temps -r -mllvm -relocation-model=pic
+; RUN: llvm-readobj -r %t-out.lto.o | FileCheck %s --check-prefix=PIC
+
+; RUN: ld.lld %t.o -o %t-out -save-temps -r --export-dynamic --noinhibit-exec -mllvm -relocation-model=static
+; RUN: llvm-readobj -r %t-out.lto.o | FileCheck %s --check-prefix=STATIC
+
+
 ; PIC: R_X86_64_REX_GOTPCRELX foo
 ; STATIC: R_X86_64_PC32 foo
 
Index: lld/include/lld/Common/TargetOptionsCommandFlags.h
===================================================================
--- lld/include/lld/Common/TargetOptionsCommandFlags.h
+++ lld/include/lld/Common/TargetOptionsCommandFlags.h
@@ -16,6 +16,7 @@
 
 namespace lld {
 llvm::TargetOptions initTargetOptionsFromCodeGenFlags();
+llvm::Optional<llvm::Reloc::Model> getRelocModelFromCMModel();
 llvm::Optional<llvm::CodeModel::Model> getCodeModelFromCMModel();
 std::string getCPUStr();
 std::vector<std::string> getMAttrs();
Index: lld/ELF/LTO.cpp
===================================================================
--- lld/ELF/LTO.cpp
+++ lld/ELF/LTO.cpp
@@ -76,7 +76,9 @@
   c.Options.FunctionSections = true;
   c.Options.DataSections = true;
 
-  if (config->relocatable)
+  if (auto relocModel = getRelocModelFromCMModel())
+    c.RelocModel = *relocModel;
+  else if (config->relocatable)
     c.RelocModel = None;
   else if (config->isPic)
     c.RelocModel = Reloc::PIC_;
Index: lld/Common/TargetOptionsCommandFlags.cpp
===================================================================
--- lld/Common/TargetOptionsCommandFlags.cpp
+++ lld/Common/TargetOptionsCommandFlags.cpp
@@ -26,6 +26,10 @@
   return ::InitTargetOptionsFromCodeGenFlags();
 }
 
+llvm::Optional<llvm::Reloc::Model> lld::getRelocModelFromCMModel() {
+  return getRelocModel();
+}
+
 llvm::Optional<llvm::CodeModel::Model> lld::getCodeModelFromCMModel() {
   return getCodeModel();
 }


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