[PATCH] D24668: [ELF] Linkerscript: do not fail if there is no space for program headers and there is PHDRS directive

[Rui Ueyama via llvm-commits]

ruiu added inline comments.

================
Comment at: ELF/LinkerScript.cpp:472-479
@@ -471,10 +471,10 @@
       Out<ELFT>::ElfHeader->getSize() + Out<ELFT>::ProgramHeaders->getSize();
-  if (HeaderSize > MinVA)
+  if (HeaderSize > HeaderVA && !hasPhdrsCommands())
     fatal("Not enough space for ELF and program headers");
 
-  // ELF and Program headers need to be right before the first section in
-  // memory. Set their addresses accordingly.
-  MinVA = alignDown(MinVA - HeaderSize, Target->PageSize);
-  Out<ELFT>::ElfHeader->setVA(MinVA);
-  Out<ELFT>::ProgramHeaders->setVA(Out<ELFT>::ElfHeader->getSize() + MinVA);
+  HeaderVA = HeaderSize > HeaderVA
+                 ? alignTo(Dot, Target->PageSize)
+                 : alignDown(HeaderVA - HeaderSize, Target->PageSize);
+  Out<ELFT>::ElfHeader->setVA(HeaderVA);
+  Out<ELFT>::ProgramHeaders->setVA(Out<ELFT>::ElfHeader->getSize() + HeaderVA);
 }
----------------
I thought about this new code probably more than 15 minutes but am still not sure if this is correct. What is the problem you are trying to fix with this change?

================
Comment at: test/ELF/linkerscript/phdrs.s:23-28
@@ +22,8 @@
+## Check PHDR VA.
+# RUN: echo "PHDRS { header PT_PHDR PHDRS; other PT_LOAD; } \
+# RUN:       SECTIONS { \
+# RUN:           . = 0; \
+# RUN:           .text : {*(.text*)} : other \
+# RUN:           .foo : {*(.foo.*)} : other \
+# RUN:           .data : {*(.data.*)} : other }" > %t.script
+# RUN: ld.lld -o %t1 --script %t.script %t
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Is this linker script expected to create a valid executable?


Repository:
  rL LLVM

https://reviews.llvm.org/D24668