[PATCH] D41551: [ELF] - Allow relocation to a weak undefined symbol when -z notext is given.

[George Rimar via Phabricator via llvm-commits]

grimar updated this revision to Diff 128151.
grimar added a comment.

- Rebased.


https://reviews.llvm.org/D41551

Files:
  ELF/Relocations.cpp
  test/ELF/retain-und.s
  test/ELF/znotext-weak-undef.s


Index: test/ELF/znotext-weak-undef.s
===================================================================
--- test/ELF/znotext-weak-undef.s
+++ test/ELF/znotext-weak-undef.s
@@ -0,0 +1,14 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+# RUN: ld.lld -z notext -shared %t.o -o %t
+# RUN: llvm-readobj -r %t | FileCheck %s
+
+# CHECK:      Relocations [
+# CHECK-NEXT: ]
+
+.text
+.global foo
+.weak foo
+
+_start:
+mov $foo,%eax
Index: test/ELF/retain-und.s
===================================================================
--- test/ELF/retain-und.s
+++ test/ELF/retain-und.s
@@ -8,9 +8,6 @@
 # RUN: llvm-readobj -r %t2.so | FileCheck %s
 
 # CHECK:      Relocations [
-# CHECK-NEXT:   Section ({{.*}}) .rela.dyn {
-# CHECK-NEXT:     0x{{.*}} R_X86_64_64 foo 0x0
-# CHECK-NEXT:   }
 # CHECK-NEXT: ]
 
 .data
Index: ELF/Relocations.cpp
===================================================================
--- ELF/Relocations.cpp
+++ ELF/Relocations.cpp
@@ -585,6 +585,19 @@
 static RelExpr adjustExpr(Symbol &Sym, RelExpr Expr, RelType Type,
                           InputSectionBase &S, uint64_t RelOff,
                           bool &IsConstant) {
+  // If a relocation can be applied at link-time, we don't need to
+  // create a dynamic relocation in the first place.
+  if (IsConstant)
+    return Expr;
+
+  // If the relocation is to a weak undef, give up on it and produce a
+  // non preemptible 0.
+  if (Sym.isUndefWeak()) {
+    Sym.IsPreemptible = false;
+    IsConstant = true;
+    return Expr;
+  }
+
   // If a section writable or if we are allowed to create dynamic relocations
   // against read-only sections (i.e. when "-z notext" is given), we can create
   // any dynamic relocation the dynamic linker knows how to handle.
@@ -596,22 +609,9 @@
     return Expr;
   }
 
-  // If a relocation can be applied at link-time, we don't need to
-  // create a dynamic relocation in the first place.
-  if (IsConstant)
-    return Expr;
-
   // If we got here we know that this relocation would require the dynamic
   // linker to write a value to read only memory.
 
-  // If the relocation is to a weak undef, give up on it and produce a
-  // non preemptible 0.
-  if (Sym.isUndefWeak()) {
-    Sym.IsPreemptible = false;
-    IsConstant = true;
-    return Expr;
-  }
-
   // We can hack around it if we are producing an executable and
   // the refered symbol can be preemepted to refer to the executable.
   if (Config->Shared || (Config->Pic && !isRelExpr(Expr))) {


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