[PATCH] D92520: [lld][WebAssembly] Fix malformed output with -pie + --shared-memory

[Sam Clegg via Phabricator via llvm-commits]

sbc100 created this revision.
Herald added subscribers: llvm-commits, wingo, ecnelises, jfb, sunfish, jgravelle-google, dschuff.
Herald added a project: LLVM.
sbc100 requested review of this revision.
Herald added a subscriber: aheejin.

The conditional guarding createInitMemoryFunction was incorrect
and didn't match that guarding the creation of the associated
symbol.

Rather that reproduce the same conditions in multiple places
we can simply use the presence of the associated symbol.

Also, add an assertion that would have caught this bug.

Also, add a new test for this flag combination.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D92520

Files:
  lld/test/wasm/data-segments.ll
  lld/wasm/MarkLive.cpp
  lld/wasm/OutputSections.cpp
  lld/wasm/SyntheticSections.cpp
  lld/wasm/Writer.cpp


Index: lld/wasm/Writer.cpp
===================================================================
--- lld/wasm/Writer.cpp
+++ lld/wasm/Writer.cpp
@@ -1214,11 +1214,12 @@
   calculateInitFunctions();
 
   if (!config->relocatable) {
-    // Create linker synthesized functions
-    if (config->isPic)
+    if (WasmSym::applyRelocs)
       createApplyRelocationsFunction();
-    else if (config->sharedMemory)
+    if (WasmSym::initMemory)
       createInitMemoryFunction();
+
+    // Create linker synthesized functions
     createCallCtorsFunction();
 
     // Create export wrappers for commands if needed.
Index: lld/wasm/SyntheticSections.cpp
===================================================================
--- lld/wasm/SyntheticSections.cpp
+++ lld/wasm/SyntheticSections.cpp
@@ -209,6 +209,7 @@
     return;
   uint32_t functionIndex =
       out.importSec->getNumImportedFunctions() + inputFunctions.size();
+  LLVM_DEBUG(dbgs() << "addFunction: " << inputFunctions.size() << "\n");
   inputFunctions.emplace_back(func);
   func->setFunctionIndex(functionIndex);
 }
Index: lld/wasm/OutputSections.cpp
===================================================================
--- lld/wasm/OutputSections.cpp
+++ lld/wasm/OutputSections.cpp
@@ -90,6 +90,8 @@
     func->outputSec = this;
     func->outputOffset = bodySize;
     func->calculateSize();
+    // All functions should have a non-empty body at this point
+    assert(func->getSize());
     bodySize += func->getSize();
   }
 
@@ -101,6 +103,7 @@
   log(" size=" + Twine(getSize()));
   log(" headersize=" + Twine(header.size()));
   log(" codeheadersize=" + Twine(codeSectionHeader.size()));
+  log(" functions=" + Twine(functions.size()));
   buf += offset;
 
   // Write section header
Index: lld/wasm/MarkLive.cpp
===================================================================
--- lld/wasm/MarkLive.cpp
+++ lld/wasm/MarkLive.cpp
@@ -96,15 +96,13 @@
     if (sym->isNoStrip() || sym->isExported())
       enqueue(sym);
 
-  // If we'll be calling the user's `__wasm_call_dtors` function, mark it live.
-  if (Symbol *callDtors = WasmSym::callDtors)
-    enqueue(callDtors);
+  if (WasmSym::callDtors)
+    enqueue(WasmSym::callDtors);
 
-  // In Emscripten-style PIC, `__wasm_call_ctors` calls `__wasm_apply_relocs`.
-  if (config->isPic)
+  if (WasmSym::applyRelocs)
     enqueue(WasmSym::applyRelocs);
 
-  if (config->sharedMemory && !config->shared)
+  if (WasmSym::initMemory)
     enqueue(WasmSym::initMemory);
 
   // Enqueue constructors in objects explicitly live from the command-line.
Index: lld/test/wasm/data-segments.ll
===================================================================
--- lld/test/wasm/data-segments.ll
+++ lld/test/wasm/data-segments.ll
@@ -13,6 +13,10 @@
 ; RUN: wasm-ld -no-gc-sections --no-entry --shared-memory --max-memory=131072 %t.atomics.bulk-mem.o -o %t.atomics.bulk-mem.wasm
 ; RUN: obj2yaml %t.atomics.bulk-mem.wasm | FileCheck %s --check-prefixes PASSIVE
 
+; Also test in combination with PIC/pie
+; RUN: llc -filetype=obj -relocation-model=pic %s -o %t.atomics.bulk-mem.pic.o -mattr=+atomics,+bulk-memory,+mutable-globals
+; RUN: wasm-ld --experimental-pic -pie -no-gc-sections --no-entry --shared-memory --max-memory=131072 %t.atomics.bulk-mem.pic.o -o %t.pic.wasm
+
 target triple = "wasm32-unknown-unknown"
 
 @a = hidden global [6 x i8] c"hello\00", align 1


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