[PATCH] D55098: Do not assume .idata is zero-initialized.

[Rui Ueyama via Phabricator via llvm-commits]

ruiu created this revision.
ruiu added a reviewer: rnk.

We initialize .text section with 0xcc (INT3 instruction), so we need to
explicitly write data even if it is zero if it can be in a .text section.
If you specify /merge:.rdata=.text, .rdata (which contains .idata) is put
to .text, so we need to do this.

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


https://reviews.llvm.org/D55098

Files:
  lld/COFF/Chunks.cpp
  lld/COFF/DLL.cpp
  lld/test/COFF/export.test


Index: lld/test/COFF/export.test
===================================================================
--- lld/test/COFF/export.test
+++ lld/test/COFF/export.test
@@ -97,3 +97,12 @@
 FORWARDER:        0        0
 FORWARDER:        1   0x1010  exportfn
 FORWARDER:        2           foo (forwarded to kernel32.foobar)
+
+# RUN: lld-link /out:%t.dll /dll %t.obj /merge:.rdata=.text /export:exportfn1 /export:exportfn2
+# RUN: llvm-objdump -p %t.dll | FileCheck -check-prefix=MERGE -match-full-lines %s
+
+MERGE:      DLL name: export.test.tmp.dll
+MERGE:      Ordinal      RVA  Name
+MERGE-NEXT:       0        0
+MERGE-NEXT:       1   0x1008  exportfn1
+MERGE-NEXT:       2   0x1010  exportfn2
Index: lld/COFF/DLL.cpp
===================================================================
--- lld/COFF/DLL.cpp
+++ lld/COFF/DLL.cpp
@@ -416,6 +416,8 @@
   size_t getSize() const override { return Size * 4; }
 
   void writeTo(uint8_t *Buf) const override {
+    memset(Buf + OutputSectionOff, 0, getSize());
+
     for (const Export &E : Config->Exports) {
       uint8_t *P = Buf + OutputSectionOff + E.Ordinal * 4;
       uint32_t Bit = 0;
Index: lld/COFF/Chunks.cpp
===================================================================
--- lld/COFF/Chunks.cpp
+++ lld/COFF/Chunks.cpp
@@ -619,6 +619,7 @@
 
 void StringChunk::writeTo(uint8_t *Buf) const {
   memcpy(Buf + OutputSectionOff, Str.data(), Str.size());
+  Buf[OutputSectionOff + Str.size()] = '\0';
 }
 
 ImportThunkChunkX64::ImportThunkChunkX64(Defined *S) : ImpSymbol(S) {


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