RuntimeDyldELF/AArch64: Implement basic GOT support

This patch implements two GOT relocations:
R_AARCH64_ADR_GOT_PAGE and R_AARCH64_LD64_GOT_LO12_NC

Differential revision: https://reviews.llvm.org/D28571

llvm-svn: 294191

1 files changed, 26 insertions, 0 deletions

diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
index 63b56f72520..9660e1acad1 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
@@ -484,6 +484,14 @@ Error RuntimeDyldImpl::computeTotalAllocSize(const ObjectFile &Obj,
     }
   }
 
+  // Compute Global Offset Table size. If it is not zero we
+  // also update alignment, which is equal to a size of a
+  // single GOT entry.
+  if (unsigned GotSize = computeGOTSize(Obj)) {
+    RWSectionSizes.push_back(GotSize);
+    RWDataAlign = std::max<uint32_t>(RWDataAlign, getGOTEntrySize());
+  }
+
   // Compute the size of all common symbols
   uint64_t CommonSize = 0;
   uint32_t CommonAlign = 1;
@@ -518,6 +526,24 @@ Error RuntimeDyldImpl::computeTotalAllocSize(const ObjectFile &Obj,
   return Error::success();
 }
 
+// compute GOT size
+unsigned RuntimeDyldImpl::computeGOTSize(const ObjectFile &Obj) {
+  size_t GotEntrySize = getGOTEntrySize();
+  if (!GotEntrySize)
+    return 0;
+
+  size_t GotSize = 0;
+  for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
+       SI != SE; ++SI) {
+
+    for (const RelocationRef &Reloc : SI->relocations())
+      if (relocationNeedsGot(Reloc))
+        GotSize += GotEntrySize;
+  }
+
+  return GotSize;
+}
+
 // compute stub buffer size for the given section
 unsigned RuntimeDyldImpl::computeSectionStubBufSize(const ObjectFile &Obj,
                                                     const SectionRef &Section) {