commit b9889bbacb4b3cf68838fb54b792435d8d9e341e
author Sam Clegg <sbc@chromium.org> Thu May 23 09:41:03 2019 +0000
committer Sam Clegg <sbc@chromium.org> Thu May 23 09:41:03 2019 +0000
tree d1f5f82cb844c36639247eaa429c7925eb38a47d
parent 0baaf45be707c9e13e9f4d74001cb87701a519c1

[WebAssembly] Seal imports section before counting imports

Summary:
Before we can assign entries in the function of global index space
we need to know the total number of function and global imports
respectively.

To avoid programmer error this change seals that imports section before
assigned function and global index space.  Any attempt to add an import
after the section is sealed will assert.

The lack this such as check caused  https://reviews.llvm.org/D61876
to be reverted.  I'm also trying to craft a test case the this
failure.

Subscribers: dschuff, jgravelle-google, aheejin, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62240

llvm-svn: 361470

lld/wasm/Writer.cpp

diff --git a/lld/wasm/Writer.cpp b/lld/wasm/Writer.cpp
index eb567ec..01dbd82 100644
--- a/lld/wasm/Writer.cpp
+++ b/lld/wasm/Writer.cpp
@@ -439,7 +439,7 @@
         WasmExport{FunctionTableName, WASM_EXTERNAL_TABLE, 0});
 
   unsigned FakeGlobalIndex =
-      Out.ImportSec->NumImportedGlobals + Out.GlobalSec->InputGlobals.size();
+      Out.ImportSec->numImportedGlobals() + Out.GlobalSec->InputGlobals.size();
 
   for (Symbol *Sym : Symtab->getSymbols()) {
     if (!Sym->isExported())
@@ -532,7 +532,9 @@
 }
 
 void Writer::assignIndexes() {
-  assert(Out.FunctionSec->InputFunctions.empty());
+  // Seal the import section, since other index spaces such as function and
+  // global are effected by the number of imports.
+  Out.ImportSec->seal();
 
   for (InputFunction *Func : Symtab->SyntheticFunctions)
     Out.FunctionSec->addFunction(Func);
@@ -543,8 +545,6 @@
       Out.FunctionSec->addFunction(Func);
   }
 
-  scanRelocations();
-
   for (InputGlobal *Global : Symtab->SyntheticGlobals)
     Out.GlobalSec->addGlobal(Global);
 
@@ -724,6 +724,8 @@
   populateTargetFeatures();
   log("-- calculateImports");
   calculateImports();
+  log("-- scanRelocations");
+  scanRelocations();
   log("-- assignIndexes");
   assignIndexes();
   log("-- calculateInitFunctions");
@@ -750,9 +752,9 @@
     log("Defined Functions: " + Twine(Out.FunctionSec->InputFunctions.size()));
     log("Defined Globals  : " + Twine(Out.GlobalSec->InputGlobals.size()));
     log("Defined Events   : " + Twine(Out.EventSec->InputEvents.size()));
-    log("Function Imports : " + Twine(Out.ImportSec->NumImportedFunctions));
-    log("Global Imports   : " + Twine(Out.ImportSec->NumImportedGlobals));
-    log("Event Imports    : " + Twine(Out.ImportSec->NumImportedEvents));
+    log("Function Imports : " + Twine(Out.ImportSec->numImportedFunctions()));
+    log("Global Imports   : " + Twine(Out.ImportSec->numImportedGlobals()));
+    log("Event Imports    : " + Twine(Out.ImportSec->numImportedEvents()));
     for (ObjFile *File : Symtab->ObjectFiles)
       File->dumpInfo();
   }