Create an instance of Target after reading all input files. NFC.

rui314 · rui314 · commit f28825bc06f9 · 2019-03-28T17:38:53.000Z
This change itself doesn't mean anything, but it helps D59780 because
in patch, we don't know whether we need to create a CET-aware PLT or
not until we read all input files.

llvm-svn: 357194
diff --git a/lld/ELF/Arch/PPC.cpp b/lld/ELF/Arch/PPC.cpp
@@ -29,7 +29,6 @@ class PPC final : public TargetInfo {
 
 PPC::PPC() {
   NoneRel = R_PPC_NONE;
-  GotBaseSymOff = 0x8000;
   GotBaseSymInGotPlt = false;
 }
 
diff --git a/lld/ELF/Arch/PPC64.cpp b/lld/ELF/Arch/PPC64.cpp
@@ -208,7 +208,6 @@ PPC64::PPC64() {
   PltEntrySize = 4;
   GotPltEntrySize = 8;
   GotBaseSymInGotPlt = false;
-  GotBaseSymOff = 0x8000;
   GotHeaderEntriesNum = 1;
   GotPltHeaderEntriesNum = 2;
   PltHeaderSize = 60;
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
@@ -1454,11 +1454,6 @@ static const char *LibcallRoutineNames[] = {
 // Do actual linking. Note that when this function is called,
 // all linker scripts have already been parsed.
 template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) {
-  Target = getTarget();
-
-  Config->MaxPageSize = getMaxPageSize(Args);
-  Config->ImageBase = getImageBase(Args);
-
   // If a -hash-style option was not given, set to a default value,
   // which varies depending on the target.
   if (!Args.hasArg(OPT_hash_style)) {
@@ -1616,12 +1611,21 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) {
 
   // We do not want to emit debug sections if --strip-all
   // or -strip-debug are given.
-  if (Config->Strip != StripPolicy::None)
+  if (Config->Strip != StripPolicy::None) {
     llvm::erase_if(InputSections, [](InputSectionBase *S) {
       return S->Name.startswith(".debug") || S->Name.startswith(".zdebug");
     });
+  }
 
+  // The Target instance handles target-specific stuff, such as applying
+  // relocations or writing a PLT section. It also contains target-dependent
+  // values such as a default image base address.
+  Target = getTarget();
+
+  Config->EFlags = Target->calcEFlags();
   Config->EFlags = Target->calcEFlags();
+  Config->MaxPageSize = getMaxPageSize(Args);
+  Config->ImageBase = getImageBase(Args);
 
   if (Config->EMachine == EM_ARM) {
     // FIXME: These warnings can be removed when lld only uses these features
diff --git a/lld/ELF/Target.h b/lld/ELF/Target.h
@@ -86,8 +86,6 @@ class TargetInfo {
 
   uint64_t getImageBase() const;
 
-  // Offset of _GLOBAL_OFFSET_TABLE_ from base of .got or .got.plt section.
-  uint64_t GotBaseSymOff = 0;
   // True if _GLOBAL_OFFSET_TABLE_ is relative to .got.plt, false if .got.
   bool GotBaseSymInGotPlt = true;
 
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
@@ -214,17 +214,24 @@ void elf::addReservedSymbols() {
   // the .got section.
   // We do not allow _GLOBAL_OFFSET_TABLE_ to be defined by input objects as the
   // correctness of some relocations depends on its value.
-  StringRef GotTableSymName =
+  StringRef GotSymName =
       (Config->EMachine == EM_PPC64) ? ".TOC." : "_GLOBAL_OFFSET_TABLE_";
-  if (Symbol *S = Symtab->find(GotTableSymName)) {
-    if (S->isDefined())
+
+  if (Symbol *S = Symtab->find(GotSymName)) {
+    if (S->isDefined()) {
       error(toString(S->File) + " cannot redefine linker defined symbol '" +
-            GotTableSymName + "'");
-    else
-      ElfSym::GlobalOffsetTable = Symtab->addDefined(
-          GotTableSymName, STV_HIDDEN, STT_NOTYPE, Target->GotBaseSymOff,
-          /*Size=*/0, STB_GLOBAL, Out::ElfHeader,
-          /*File=*/nullptr);
+            GotSymName + "'");
+      return;
+    }
+
+    uint64_t GotOff = 0;
+    if (Config->EMachine == EM_PPC || Config->EMachine == EM_PPC64)
+      GotOff = 0x8000;
+
+    ElfSym::GlobalOffsetTable =
+        Symtab->addDefined(GotSymName, STV_HIDDEN, STT_NOTYPE, GotOff,
+                           /*Size=*/0, STB_GLOBAL, Out::ElfHeader,
+                           /*File=*/nullptr);
   }
 
   // __ehdr_start is the location of ELF file headers. Note that we define

Original file line number	Diff line number	Diff line change
`@@ -29,7 +29,6 @@ class PPC final : public TargetInfo {`
`29`	`29`
`30`	`30`	`PPC::PPC() {`
`31`	`31`	`NoneRel = R_PPC_NONE;`
`32`		`- GotBaseSymOff = 0x8000;`
`33`	`32`	`GotBaseSymInGotPlt = false;`
`34`	`33`	`}`
`35`	`34`