[PATCH] D72474: [ELF] Make TargetInfo::writeIgotPlt a no-op

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added reviewers: grimar, peter.smith, ruiu.
Herald added subscribers: llvm-commits, kristof.beyls, arichardson, emaste.
Herald added a reviewer: espindola.
Herald added a project: LLVM.

RELA targets don't read initial .got.plt entries.
REL targets (ARM, x86-32) write the address of the IFUNC resolver to the
entry (`write32le(buf, s.getVA())`).

The default writeIgotPlt() is not meaningful. Make it a no-op. AArch64
and x86-64 will have 0 as initial .got.plt entries associated with
IFUNC.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D72474

Files:
  lld/ELF/Target.cpp
  lld/ELF/Target.h
  lld/test/ELF/aarch64-gnu-ifunc-plt.s
  lld/test/ELF/gnu-ifunc-plt.s


Index: lld/test/ELF/gnu-ifunc-plt.s
===================================================================
--- lld/test/ELF/gnu-ifunc-plt.s
+++ lld/test/ELF/gnu-ifunc-plt.s
@@ -25,8 +25,8 @@
 // GOTPLT: Contents of section .got.plt:
 // GOTPLT-NEXT:  203430 40232000 00000000 00000000 00000000
 // GOTPLT-NEXT:  203440 00000000 00000000 06132000 00000000
-// GOTPLT-NEXT:  203450 16132000 00000000 26132000 00000000
-// GOTPLT-NEXT:  203460 36132000 00000000
+// GOTPLT-NEXT:  203450 16132000 00000000 00000000 00000000
+// GOTPLT-NEXT:  203460 00000000 00000000
 
 // Check that the PLTRELSZ tag does not include the IRELATIVE relocations
 // CHECK: DynamicSection [
Index: lld/test/ELF/aarch64-gnu-ifunc-plt.s
===================================================================
--- lld/test/ELF/aarch64-gnu-ifunc-plt.s
+++ lld/test/ELF/aarch64-gnu-ifunc-plt.s
@@ -23,8 +23,8 @@
 // GOTPLT: Contents of section .got.plt:
 // GOTPLT-NEXT:  230440 00000000 00000000 00000000 00000000
 // GOTPLT-NEXT:  230450 00000000 00000000 f0022100 00000000
-// GOTPLT-NEXT:  230460 f0022100 00000000 f0022100 00000000
-// GOTPLT-NEXT:  230470 f0022100 00000000
+// GOTPLT-NEXT:  230460 f0022100 00000000 00000000 00000000
+// GOTPLT-NEXT:  230470 00000000 00000000
 
 // Check that the PLTRELSZ tag does not include the IRELATIVE relocations
 // CHECK: DynamicSection [
Index: lld/ELF/Target.h
===================================================================
--- lld/ELF/Target.h
+++ lld/ELF/Target.h
@@ -32,7 +32,7 @@
   virtual void writeGotPltHeader(uint8_t *buf) const {}
   virtual void writeGotHeader(uint8_t *buf) const {}
   virtual void writeGotPlt(uint8_t *buf, const Symbol &s) const {};
-  virtual void writeIgotPlt(uint8_t *buf, const Symbol &s) const;
+  virtual void writeIgotPlt(uint8_t *buf, const Symbol &s) const {}
   virtual int64_t getImplicitAddend(const uint8_t *buf, RelType type) const;
   virtual int getTlsGdRelaxSkip(RelType type) const { return 1; }
 
Index: lld/ELF/Target.cpp
===================================================================
--- lld/ELF/Target.cpp
+++ lld/ELF/Target.cpp
@@ -144,10 +144,6 @@
   return true;
 }
 
-void TargetInfo::writeIgotPlt(uint8_t *buf, const Symbol &s) const {
-  writeGotPlt(buf, s);
-}
-
 RelExpr TargetInfo::adjustRelaxExpr(RelType type, const uint8_t *data,
                                     RelExpr expr) const {
   return expr;


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