[PATCH] D37561: [ELF] - Don't crash when --emit-relocs is used with --gc-sections

[George Rimar via Phabricator via llvm-commits]

grimar created this revision.
Herald added a subscriber: emaste.

This is PR34512.
We crashed when --emit-relocs was used
and relocated section was collected by GC.


https://reviews.llvm.org/D37561

Files:
  ELF/OutputSections.cpp
  test/ELF/emit-relocs-gc.s


Index: test/ELF/emit-relocs-gc.s
===================================================================
--- test/ELF/emit-relocs-gc.s
+++ test/ELF/emit-relocs-gc.s
@@ -0,0 +1,18 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+
+## Show that we emit .rela.bar when GC is disabled.
+# RUN: ld.lld --emit-relocs %t.o -o %t
+# RUN: llvm-objdump %t -section-headers | FileCheck %s --check-prefix=NOGC
+# NOGC: .rela.bar
+
+## GC collects .bar section and we exclude .rela.bar from output.
+# RUN: ld.lld --gc-sections --emit-relocs --print-gc-sections %t.o -o %t \
+# RUN:   | FileCheck --check-prefix=MSG %s
+# MSG: removing unused section from '.bar' in file
+# MSG: removing unused section from '.rela.bar' in file
+# RUN: llvm-objdump %t -section-headers | FileCheck %s --check-prefix=GC
+# GC-NOT:  rela.bar
+
+.section .bar,"a"
+.quad .bar
Index: ELF/OutputSections.cpp
===================================================================
--- ELF/OutputSections.cpp
+++ ELF/OutputSections.cpp
@@ -227,8 +227,10 @@
   if (!isa<SyntheticSection>(IS) &&
       (IS->Type == SHT_REL || IS->Type == SHT_RELA)) {
     auto *Sec = cast<InputSection>(IS);
-    OutputSection *Out = Sec->getRelocatedSection()->getOutputSection();
-    addInputSec(IS, OutsecName, Out->RelocationSection);
+    if (OutputSection *Out = Sec->getRelocatedSection()->getOutputSection())
+      addInputSec(IS, OutsecName, Out->RelocationSection);
+    else
+      reportDiscarded(IS);
     return;
   }
 


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