[PATCH] D158909: [JITLink] Honor shouldAddDefaultPasses in x86-64 ELF

[Rafael Auler via Phabricator via llvm-commits]

rafauler created this revision.
rafauler added reviewers: bolt, lhames, jobnoorman.
Herald added subscribers: pengfei, hiraditya.
Herald added a project: All.
rafauler requested review of this revision.
Herald added subscribers: llvm-commits, wangpc.
Herald added a project: LLVM.

The x86-64 ELF backend still tries to add a single default
pass even if shouldAddDefaultPasses is set to false. This pass doesn't
help much as it depends on x86_64::GOTTableManager being initialized
by buildTables_ELF_x86_64, which never happens when
shouldAddDefaultPasses is false, but the pass still ends up
registering a _GLOBAL_OFFSET_SYMBOL_ definition that is not very
helpful. When a client asks default passes to not run, I think it
makes sense to treat _GLOBAL_OFFSET_SYMBOL_ as an external that needs
to be resolved by the client, which is the goal of this patch. This is
used for BOLT, a client that resolves all symbols by itself.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D158909

Files:
  llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp


Index: llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
===================================================================
--- llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
+++ llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
@@ -240,10 +240,11 @@
 public:
   ELFJITLinker_x86_64(std::unique_ptr<JITLinkContext> Ctx,
                       std::unique_ptr<LinkGraph> G,
-                      PassConfiguration PassConfig)
+                      PassConfiguration PassConfig, bool DefaultPasses)
       : JITLinker(std::move(Ctx), std::move(G), std::move(PassConfig)) {
-    getPassConfig().PostAllocationPasses.push_back(
-        [this](LinkGraph &G) { return getOrCreateGOTSymbol(G); });
+    if (DefaultPasses)
+      getPassConfig().PostAllocationPasses.push_back(
+          [this](LinkGraph &G) { return getOrCreateGOTSymbol(G); });
   }
 
 private:
@@ -363,9 +364,9 @@
 void link_ELF_x86_64(std::unique_ptr<LinkGraph> G,
                      std::unique_ptr<JITLinkContext> Ctx) {
   PassConfiguration Config;
-
+  bool DefaultPasses = false;
   if (Ctx->shouldAddDefaultTargetPasses(G->getTargetTriple())) {
-
+    DefaultPasses = true;
     Config.PrePrunePasses.push_back(DWARFRecordSectionSplitter(".eh_frame"));
     Config.PrePrunePasses.push_back(EHFrameEdgeFixer(
         ".eh_frame", x86_64::PointerSize, x86_64::Pointer32, x86_64::Pointer64,
@@ -394,7 +395,8 @@
   if (auto Err = Ctx->modifyPassConfig(*G, Config))
     return Ctx->notifyFailed(std::move(Err));
 
-  ELFJITLinker_x86_64::link(std::move(Ctx), std::move(G), std::move(Config));
+  ELFJITLinker_x86_64::link(std::move(Ctx), std::move(G), std::move(Config),
+                            DefaultPasses);
 }
 } // end namespace jitlink
 } // end namespace llvm


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