[lld] r352082 - Fix broken export table if .rdata is merged with .text.

[Rui Ueyama via llvm-commits]

Author: ruiu
Date: Thu Jan 24 11:02:31 2019
New Revision: 352082

URL: http://llvm.org/viewvc/llvm-project?rev=352082&view=rev
Log:
Fix broken export table if .rdata is merged with .text.

Previously, we assumed that .rdata is zero-filled, so when writing
an COFF import table, we didn't write anything if the data is zero.
That assumption was wrong because .rdata can be merged with .text.
If .rdata is merged with .text, they are initialized with 0xcc which
is a trap instruction.

This patch removes that assumption from code.

Should be merged to 8.0 branch as this is a regression.

Fixes https://bugs.llvm.org/show_bug.cgi?id=39826

Differential Revision: https://reviews.llvm.org/D57168

Modified:
    lld/trunk/COFF/DLL.cpp
    lld/trunk/test/COFF/imports.test

Modified: lld/trunk/COFF/DLL.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/DLL.cpp?rev=352082&r1=352081&r2=352082&view=diff
==============================================================================
--- lld/trunk/COFF/DLL.cpp (original)
+++ lld/trunk/COFF/DLL.cpp Thu Jan 24 11:02:31 2019
@@ -46,6 +46,7 @@ public:
   }
 
   void writeTo(uint8_t *Buf) const override {
+    memset(Buf + OutputSectionOff, 0, getSize());
     write16le(Buf + OutputSectionOff, Hint);
     memcpy(Buf + OutputSectionOff + 2, Name.data(), Name.size());
   }
@@ -62,7 +63,10 @@ public:
   size_t getSize() const override { return Config->Wordsize; }
 
   void writeTo(uint8_t *Buf) const override {
-    write32le(Buf + OutputSectionOff, HintName->getRVA());
+    if (Config->is64())
+      write64le(Buf + OutputSectionOff, HintName->getRVA());
+    else
+      write32le(Buf + OutputSectionOff, HintName->getRVA());
   }
 
   Chunk *HintName;
@@ -98,6 +102,8 @@ public:
   size_t getSize() const override { return sizeof(ImportDirectoryTableEntry); }
 
   void writeTo(uint8_t *Buf) const override {
+    memset(Buf + OutputSectionOff, 0, getSize());
+
     auto *E = (coff_import_directory_table_entry *)(Buf + OutputSectionOff);
     E->ImportLookupTableRVA = LookupTab->getRVA();
     E->NameRVA = DLLName->getRVA();
@@ -117,6 +123,10 @@ public:
   bool hasData() const override { return false; }
   size_t getSize() const override { return Size; }
 
+  void writeTo(uint8_t *Buf) const override {
+    memset(Buf + OutputSectionOff, 0, Size);
+  }
+
 private:
   size_t Size;
 };
@@ -159,6 +169,8 @@ public:
   }
 
   void writeTo(uint8_t *Buf) const override {
+    memset(Buf + OutputSectionOff, 0, getSize());
+
     auto *E = (delay_import_directory_table_entry *)(Buf + OutputSectionOff);
     E->Attributes = 1;
     E->Name = DLLName->getRVA();
@@ -391,6 +403,8 @@ public:
   }
 
   void writeTo(uint8_t *Buf) const override {
+    memset(Buf + OutputSectionOff, 0, getSize());
+
     auto *E = (export_directory_table_entry *)(Buf + OutputSectionOff);
     E->NameRVA = DLLName->getRVA();
     E->OrdinalBase = 0;

Modified: lld/trunk/test/COFF/imports.test
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/COFF/imports.test?rev=352082&r1=352081&r2=352082&view=diff
==============================================================================
--- lld/trunk/test/COFF/imports.test (original)
+++ lld/trunk/test/COFF/imports.test Thu Jan 24 11:02:31 2019
@@ -34,3 +34,16 @@ IMPORT-NEXT:   Symbol: ExitProcess (0)
 IMPORT-NEXT:   Symbol:  (50)
 IMPORT-NEXT:   Symbol: MessageBoxA (1)
 IMPORT-NEXT: }
+
+# RUN: lld-link /out:%t.exe /entry:main /subsystem:console /merge:.rdata=.text \
+# RUN:   %p/Inputs/hello64.obj %p/Inputs/std64.lib /include:ExitProcess
+# RUN: llvm-readobj -coff-imports %t.exe | FileCheck -check-prefix=MERGE %s
+
+MERGE:      Import {
+MERGE-NEXT:   Name: std64.dll
+MERGE-NEXT:   ImportLookupTableRVA: 0x1090
+MERGE-NEXT:   ImportAddressTableRVA: 0x10B0
+MERGE-NEXT:   Symbol: ExitProcess (0)
+MERGE-NEXT:   Symbol:  (50)
+MERGE-NEXT:   Symbol: MessageBoxA (1)
+MERGE-NEXT: }