[ORC][ORC_RT] Handle ELF .init_array with non-default priority

ELF-based platforms currently support defining multiple static
initializer table sections with differing priorities, for example
.init_array.0 or .init_array.100; the default .init_array corresponds
to a priority of 65535. When building a shared library or executable,
the system linker normally sorts these sections and combines them into
a single .init_array section. This change adds the capability to
recognize ELF static initializers with priorities other than the
default, and to properly sort them by priority, to Orc and the Orc
runtime.

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D127056

2 files changed, 15 insertions, 16 deletions

diff --git a/llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp b/llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp
index 730e193..e476c54 100644
--- a/llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ELFNixPlatform.cpp
@@ -101,8 +101,6 @@ StringRef InitArrayFuncSectionName = ".init_array";
 StringRef ThreadBSSSectionName = ".tbss";
 StringRef ThreadDataSectionName = ".tdata";
 
-StringRef InitSectionNames[] = {InitArrayFuncSectionName};
-
 } // end anonymous namespace
 
 namespace llvm {
@@ -274,10 +272,9 @@ ELFNixPlatform::standardRuntimeUtilityAliases() {
 }
 
 bool ELFNixPlatform::isInitializerSection(StringRef SecName) {
-  for (auto &Name : InitSectionNames) {
-    if (Name.equals(SecName))
-      return true;
-  }
+  if (SecName.consume_front(InitArrayFuncSectionName) &&
+      (SecName.empty() || SecName[0] == '.'))
+    return true;
   return false;
 }
 
@@ -781,16 +778,15 @@ Error ELFNixPlatform::ELFNixPlatformPlugin::preserveInitSections(
     jitlink::LinkGraph &G, MaterializationResponsibility &MR) {
 
   JITLinkSymbolSet InitSectionSymbols;
-  for (auto &InitSectionName : InitSectionNames) {
+  for (auto &InitSection : G.sections()) {
     // Skip non-init sections.
-    auto *InitSection = G.findSectionByName(InitSectionName);
-    if (!InitSection)
+    if (!isInitializerSection(InitSection.getName()))
       continue;
 
     // Make a pass over live symbols in the section: those blocks are already
     // preserved.
     DenseSet<jitlink::Block *> AlreadyLiveBlocks;
-    for (auto &Sym : InitSection->symbols()) {
+    for (auto &Sym : InitSection.symbols()) {
       auto &B = Sym->getBlock();
       if (Sym->isLive() && Sym->getOffset() == 0 &&
           Sym->getSize() == B.getSize() && !AlreadyLiveBlocks.count(&B)) {
@@ -800,7 +796,7 @@ Error ELFNixPlatform::ELFNixPlatformPlugin::preserveInitSections(
     }
 
     // Add anonymous symbols to preserve any not-already-preserved blocks.
-    for (auto *B : InitSection->blocks())
+    for (auto *B : InitSection.blocks())
       if (!AlreadyLiveBlocks.count(B))
         InitSectionSymbols.insert(
             &G.addAnonymousSymbol(*B, 0, B->getSize(), false, true));
@@ -821,9 +817,9 @@ Error ELFNixPlatform::ELFNixPlatformPlugin::registerInitSections(
 
   LLVM_DEBUG({ dbgs() << "ELFNixPlatform::registerInitSections\n"; });
 
-  for (auto InitSectionName : InitSectionNames) {
-    if (auto *Sec = G.findSectionByName(InitSectionName)) {
-      InitSections.push_back(Sec);
+  for (auto &Sec : G.sections()) {
+    if (isInitializerSection(Sec.getName())) {
+      InitSections.push_back(&Sec);
     }
   }
 
diff --git a/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp b/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
index 4461b6c..5ddb35c 100644
--- a/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
@@ -78,9 +78,12 @@ private:
   }
 
   static bool hasELFInitSection(LinkGraph &G) {
-    for (auto &Sec : G.sections())
-      if (Sec.getName() == ".init_array")
+    for (auto &Sec : G.sections()) {
+      auto SecName = Sec.getName();
+      if (SecName.consume_front(".init_array") &&
+          (SecName.empty() || SecName[0] == '.'))
         return true;
+    }
     return false;
   }