[PATCH] D44601: LLD: Avoid segfault on FreeBSD with --emit-relocs

[Domagoj Stolfa via Phabricator via llvm-commits]

dstolfa updated this revision to Diff 138827.
dstolfa added a comment.

Generate a minimal test case for the breakage. It seems like the root cause of this are the cfi sections.


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D44601

Files:
  ELF/LinkerScript.cpp
  ELF/Writer.cpp
  test/ELF/emit-relocs-freebsd.s


Index: test/ELF/emit-relocs-freebsd.s
===================================================================
--- /dev/null
+++ test/ELF/emit-relocs-freebsd.s
@@ -0,0 +1,68 @@
+# REQUIRES: x86
+# RUN: llvm-mc -triple=x86_64-unknown-freebsd -filetype=obj %s -o %t1.o
+# RUN: ld.lld %t1.o --emit-relocs -o %t
+# RUN: llvm-readobj -t -r -s %t | FileCheck %s
+
+## Check single dash form.
+# RUN: ld.lld -emit-relocs %t1.o -o %t1
+# RUN llvm-read-obj -t -r -s %t1 | FileCheck %s
+
+## Check alias.
+# RUN: ld.lld -q %t1.o -o %t2
+# RUN: llvm-readobj -t -r -s %t2 | FileCheck %s
+
+# CHECK:        Section {
+# CHECK:          Index: 2
+# CHECK-NEXT:     Name: .text
+# CHECK-NEXT:     Type: SHT_PROGBITS
+# CHECK-NEXT:     Flags [
+# CHECK-NEXT:       SHF_ALLOC
+# CHECK-NEXT:       SHF_EXECINSTR
+# CHECK-NEXT:     ]
+# CHECK:        Relocations [
+# CHECK-NEXT:   ] 
+# CHECK-NEXT:   Symbols [
+# CHECK-NEXT:     Symbol {
+# CHECK-NEXT:       Name:
+# CHECK-NEXT:       Value: 0x0
+# CHECK-NEXT:       Size: 0
+# CHECK-NEXT:       Binding: Local
+# CHECK-NEXT:       Type: None
+# CHECK-NEXT:       Other: 0
+# CHECK-NEXT:       Section: Undefined
+# CHECK-NEXT:     }
+# CHECK-NEXT:     Symbol {
+# CHECK-NEXT:       Name:
+# CHECK-NEXT:       Value: 0x201000
+# CHECK-NEXT:       Size: 0
+# CHECK-NEXT:       Binding: Local
+# CHECK-NEXT:       Type: Section
+# CHECK-NEXT:       Other: 0
+# CHECK-NEXT:       Section: .text
+# CHECK-NEXT:     }
+# CHECK-NEXT:     Symbol {
+# CHECK-NEXT:       Name:
+# CHECK-NEXT:       Value: 0x0
+# CHECK-NEXT:       Size: 0
+# CHECK-NEXT:       Binding: Local
+# CHECK-NEXT:       Type: Section
+# CHECK-NEXT:       Other: 0
+# CHECK-NEXT:       Section: .comment
+# CHECK-NEXT:     }
+# CHECK-NEXT:     Symbol {
+# CHECK-NEXT:       Name: _start
+# CHECK-NEXT:       Value: 0x201000
+# CHECK-NEXT:       Size: 0
+# CHECK-NEXT:       Binding: Global
+# CHECK-NEXT:       Type: None
+# CHECK-NEXT:       Other: 0
+# CHECK-NEXT:       Section: .text
+# CHECK-NEXT:     }
+# CHECK-NEXT:   ]
+
+.text
+.globl _start
+_start:
+.cfi_startproc
+  nop
+.cfi_endproc
Index: ELF/Writer.cpp
===================================================================
--- ELF/Writer.cpp
+++ ELF/Writer.cpp
@@ -98,6 +98,8 @@
       !isa<SyntheticSection>(S)) {
     OutputSection *Out =
         cast<InputSection>(S)->getRelocatedSection()->getOutputSection();
+    if (!Out)
+      return "";
     if (S->Type == SHT_RELA)
       return Saver.save(".rela" + Out->Name);
     return Saver.save(".rel" + Out->Name);
Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -628,6 +628,8 @@
       continue;
 
     StringRef Name = getOutputSectionName(S);
+    if (Name == "")
+      continue;
 
     if (Config->OrphanHandling == OrphanHandlingPolicy::Error)
       error(toString(S) + " is being placed in '" + Name + "'");


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