[llvm] 5e3200f - [JITLink][ELF] Add support for reading extended table

[Steven Wu via llvm-commits]

Author: Steven Wu
Date: 2021-11-30T09:18:42-08:00
New Revision: 5e3200f3ce5ac807fa0fdd2b12484ee1540c6b50

URL: https://github.com/llvm/llvm-project/commit/5e3200f3ce5ac807fa0fdd2b12484ee1540c6b50
DIFF: https://github.com/llvm/llvm-project/commit/5e3200f3ce5ac807fa0fdd2b12484ee1540c6b50.diff

LOG: [JITLink][ELF] Add support for reading extended table

Add support for reading extended table in ELF object file. This allows
JITLink to support ELF object files with many sections.

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D114747

Added: 
    llvm/test/ExecutionEngine/JITLink/X86/ELF_shndex.s

Modified: 
    llvm/lib/ExecutionEngine/JITLink/ELFLinkGraphBuilder.h

Removed: 
    


################################################################################
diff  --git a/llvm/lib/ExecutionEngine/JITLink/ELFLinkGraphBuilder.h b/llvm/lib/ExecutionEngine/JITLink/ELFLinkGraphBuilder.h
index fdc9877512862..d141072891f4f 100644
--- a/llvm/lib/ExecutionEngine/JITLink/ELFLinkGraphBuilder.h
+++ b/llvm/lib/ExecutionEngine/JITLink/ELFLinkGraphBuilder.h
@@ -143,6 +143,9 @@ class ELFLinkGraphBuilder : public ELFLinkGraphBuilderBase {
   // Only SHF_ALLOC sections will have graph sections.
   DenseMap<ELFSectionIndex, Section *> GraphSections;
   DenseMap<ELFSymbolIndex, Symbol *> GraphSymbols;
+  DenseMap<const typename ELFFile::Elf_Shdr *,
+           ArrayRef<typename ELFFile::Elf_Word>>
+      ShndxTables;
 };
 
 template <typename ELFT>
@@ -241,7 +244,7 @@ template <typename ELFT> Error ELFLinkGraphBuilder<ELFT>::prepare() {
     return SectionStringTabOrErr.takeError();
 
   // Get the SHT_SYMTAB section.
-  for (auto &Sec : Sections)
+  for (auto &Sec : Sections) {
     if (Sec.sh_type == ELF::SHT_SYMTAB) {
       if (!SymTabSec)
         SymTabSec = &Sec;
@@ -250,6 +253,20 @@ template <typename ELFT> Error ELFLinkGraphBuilder<ELFT>::prepare() {
                                         G->getName());
     }
 
+    // Extended table.
+    if (Sec.sh_type == ELF::SHT_SYMTAB_SHNDX) {
+      uint32_t SymtabNdx = Sec.sh_link;
+      if (SymtabNdx >= Sections.size())
+        return make_error<JITLinkError>("sh_link is out of bound");
+
+      auto ShndxTable = Obj.getSHNDXTable(Sec);
+      if (!ShndxTable)
+        return ShndxTable.takeError();
+
+      ShndxTables.insert({&Sections[SymtabNdx], *ShndxTable});
+    }
+  }
+
   return Error::success();
 }
 
@@ -401,9 +418,19 @@ template <typename ELFT> Error ELFLinkGraphBuilder<ELFT>::graphifySymbols() {
         (Sym.getType() == ELF::STT_NOTYPE || Sym.getType() == ELF::STT_FUNC ||
          Sym.getType() == ELF::STT_OBJECT ||
          Sym.getType() == ELF::STT_SECTION || Sym.getType() == ELF::STT_TLS)) {
-
-      // FIXME: Handle extended tables.
-      if (auto *GraphSec = getGraphSection(Sym.st_shndx)) {
+      // Handle extended tables.
+      unsigned Shndx = Sym.st_shndx;
+      if (Shndx == ELF::SHN_XINDEX) {
+        auto ShndxTable = ShndxTables.find(SymTabSec);
+        if (ShndxTable == ShndxTables.end())
+          continue;
+        auto NdxOrErr = object::getExtendedSymbolTableIndex<ELFT>(
+            Sym, SymIndex, ShndxTable->second);
+        if (!NdxOrErr)
+          return NdxOrErr.takeError();
+        Shndx = *NdxOrErr;
+      }
+      if (auto *GraphSec = getGraphSection(Shndx)) {
         Block *B = nullptr;
         {
           auto Blocks = GraphSec->blocks();

diff  --git a/llvm/test/ExecutionEngine/JITLink/X86/ELF_shndex.s b/llvm/test/ExecutionEngine/JITLink/X86/ELF_shndex.s
new file mode 100644
index 0000000000000..68039d5946554
--- /dev/null
+++ b/llvm/test/ExecutionEngine/JITLink/X86/ELF_shndex.s
@@ -0,0 +1,105 @@
+// Test object file with extended symbol table can be linked.
+
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o %t
+// RUN: llvm-jitlink -noexec %t
+
+.macro gen_sections4 x
+        .section a\x
+        .section b\x
+        .section c\x
+        .section d\x
+.endm
+
+.macro gen_sections8 x
+        gen_sections4 a\x
+        gen_sections4 b\x
+.endm
+
+.macro gen_sections16 x
+        gen_sections8 a\x
+        gen_sections8 b\x
+.endm
+
+.macro gen_sections32 x
+        gen_sections16 a\x
+        gen_sections16 b\x
+.endm
+
+.macro gen_sections64 x
+        gen_sections32 a\x
+        gen_sections32 b\x
+.endm
+
+.macro gen_sections128 x
+        gen_sections64 a\x
+        gen_sections64 b\x
+.endm
+
+.macro gen_sections256 x
+        gen_sections128 a\x
+        gen_sections128 b\x
+.endm
+
+.macro gen_sections512 x
+        gen_sections256 a\x
+        gen_sections256 b\x
+.endm
+
+.macro gen_sections1024 x
+        gen_sections512 a\x
+        gen_sections512 b\x
+.endm
+
+.macro gen_sections2048 x
+        gen_sections1024 a\x
+        gen_sections1024 b\x
+.endm
+
+.macro gen_sections4096 x
+        gen_sections2048 a\x
+        gen_sections2048 b\x
+.endm
+
+.macro gen_sections8192 x
+        gen_sections4096 a\x
+        gen_sections4096 b\x
+.endm
+
+.macro gen_sections16384 x
+        gen_sections8192 a\x
+        gen_sections8192 b\x
+.endm
+
+.macro gen_sections32768 x
+        gen_sections16384 a\x
+        gen_sections16384 b\x
+.endm
+
+        .section foo
+        .section bar
+
+gen_sections32768 a
+gen_sections16384 b
+gen_sections8192 c
+gen_sections4096 d
+gen_sections2048 e
+gen_sections1024 f
+gen_sections512 g
+gen_sections128 h
+gen_sections64 i
+gen_sections32 j
+gen_sections16 k
+gen_sections8 l
+gen_sections4 m
+
+.section test,"ax"
+.global a
+a:
+nop
+.size   a, .-a
+
+.text
+.global main
+main:
+nop
+.size   main, .-main