From 9fbfd76fe3061d9e02aaed704b439dcff750af1d Mon Sep 17 00:00:00 2001 From: Rui Ueyama Date: Thu, 18 May 2017 19:59:22 +0000 Subject: [PATCH] Merge IAT and ILT. Previously, LLD-produced executables had IAT (Import Address Table) and ILT (Import Lookup Table) as separate chunks of data, although their contents are identical. My interpretation of the COFF spec when I wrote the COFF linker is that they need to be separate tables even though they are the same. But Peter found that the Windows loader is fine with executables in which IAT and ILT are merged. This is a patch to merge IAT and ILT. I confirmed that an lld-link self-hosted with this patch works fine. Fixes https://bugs.llvm.org/show_bug.cgi?id=33064 Differential Revision: https://reviews.llvm.org/D33326 llvm-svn: 303374 --- lld/COFF/DLL.cpp | 15 +++++++-------- lld/COFF/DLL.h | 1 - lld/test/COFF/armnt-imports.test | 2 +- lld/test/COFF/hello32.test | 4 ++-- lld/test/COFF/imports.test | 8 ++++---- 5 files changed, 14 insertions(+), 16 deletions(-) diff --git a/lld/COFF/DLL.cpp b/lld/COFF/DLL.cpp index d76410b..3ac14e4 100644 --- a/lld/COFF/DLL.cpp +++ b/lld/COFF/DLL.cpp @@ -100,13 +100,17 @@ public: void writeTo(uint8_t *Buf) const override { auto *E = (coff_import_directory_table_entry *)(Buf + OutputSectionOff); - E->ImportLookupTableRVA = LookupTab->getRVA(); E->NameRVA = DLLName->getRVA(); + + // The import descriptor table contains two pointers to + // the tables describing dllimported symbols. But the + // Windows loader actually uses only one. So we create + // only one table and set both fields to its address. + E->ImportLookupTableRVA = AddressTab->getRVA(); E->ImportAddressTableRVA = AddressTab->getRVA(); } Chunk *DLLName; - Chunk *LookupTab; Chunk *AddressTab; }; @@ -388,7 +392,6 @@ std::vector IdataContents::getChunks() { // Add each type in the correct order. std::vector V; V.insert(V.end(), Dirs.begin(), Dirs.end()); - V.insert(V.end(), Lookups.begin(), Lookups.end()); V.insert(V.end(), Addresses.begin(), Addresses.end()); V.insert(V.end(), Hints.begin(), Hints.end()); V.insert(V.end(), DLLNames.begin(), DLLNames.end()); @@ -404,21 +407,18 @@ void IdataContents::create() { // we need to create HintName chunks to store the names. // If they don't (if they are import-by-ordinals), we store only // ordinal values to the table. - size_t Base = Lookups.size(); + size_t Base = Addresses.size(); for (DefinedImportData *S : Syms) { uint16_t Ord = S->getOrdinal(); if (S->getExternalName().empty()) { - Lookups.push_back(make(Ord)); Addresses.push_back(make(Ord)); continue; } auto *C = make(S->getExternalName(), Ord); - Lookups.push_back(make(C)); Addresses.push_back(make(C)); Hints.push_back(C); } // Terminate with null values. - Lookups.push_back(make(ptrSize())); Addresses.push_back(make(ptrSize())); for (int I = 0, E = Syms.size(); I < E; ++I) @@ -427,7 +427,6 @@ void IdataContents::create() { // Create the import table header. DLLNames.push_back(make(Syms[0]->getDLLName())); auto *Dir = make(DLLNames.back()); - Dir->LookupTab = Lookups[Base]; Dir->AddressTab = Addresses[Base]; Dirs.push_back(Dir); } diff --git a/lld/COFF/DLL.h b/lld/COFF/DLL.h index ad31278..939771b 100644 --- a/lld/COFF/DLL.h +++ b/lld/COFF/DLL.h @@ -36,7 +36,6 @@ private: std::vector Imports; std::vector Dirs; - std::vector Lookups; std::vector Addresses; std::vector Hints; std::vector DLLNames; diff --git a/lld/test/COFF/armnt-imports.test b/lld/test/COFF/armnt-imports.test index 519886e..f0aaebd 100644 --- a/lld/test/COFF/armnt-imports.test +++ b/lld/test/COFF/armnt-imports.test @@ -6,7 +6,7 @@ # CHECK: Import { # CHECK: Name: library.dll # CHECK: ImportLookupTableRVA: 0x2028 -# CHECK: ImportAddressTableRVA: 0x2030 +# CHECK: ImportAddressTableRVA: 0x2028 # CHECK: Symbol: function (0) # CHECK: } diff --git a/lld/test/COFF/hello32.test b/lld/test/COFF/hello32.test index b7bc887..e6117b9 100644 --- a/lld/test/COFF/hello32.test +++ b/lld/test/COFF/hello32.test @@ -77,7 +77,7 @@ HEADER-NEXT: LoadConfigTableRVA: 0x0 HEADER-NEXT: LoadConfigTableSize: 0x0 HEADER-NEXT: BoundImportRVA: 0x0 HEADER-NEXT: BoundImportSize: 0x0 -HEADER-NEXT: IATRVA: 0x3034 +HEADER-NEXT: IATRVA: 0x3028 HEADER-NEXT: IATSize: 0xC HEADER-NEXT: DelayImportDescriptorRVA: 0x0 HEADER-NEXT: DelayImportDescriptorSize: 0x0 @@ -113,7 +113,7 @@ IMPORTS: AddressSize: 32bit IMPORTS: Import { IMPORTS: Name: std32.dll IMPORTS: ImportLookupTableRVA: 0x3028 -IMPORTS: ImportAddressTableRVA: 0x3034 +IMPORTS: ImportAddressTableRVA: 0x3028 IMPORTS: Symbol: ExitProcess (0) IMPORTS: Symbol: MessageBoxA (1) IMPORTS: } diff --git a/lld/test/COFF/imports.test b/lld/test/COFF/imports.test index 584c24e..4df6d49 100644 --- a/lld/test/COFF/imports.test +++ b/lld/test/COFF/imports.test @@ -21,14 +21,14 @@ TEXT-NEXT: callq 60 TEXT-NEXT: movl $0, %ecx TEXT-NEXT: callq 18 TEXT-NEXT: callq 29 -TEXT: jmpq *4098(%rip) -TEXT: jmpq *4090(%rip) -TEXT: jmpq *4082(%rip) +TEXT: jmpq *4066(%rip) +TEXT: jmpq *4058(%rip) +TEXT: jmpq *4050(%rip) IMPORT: Import { IMPORT-NEXT: Name: std64.dll IMPORT-NEXT: ImportLookupTableRVA: 0x3028 -IMPORT-NEXT: ImportAddressTableRVA: 0x3048 +IMPORT-NEXT: ImportAddressTableRVA: 0x3028 IMPORT-NEXT: Symbol: ExitProcess (0) IMPORT-NEXT: Symbol: (50) IMPORT-NEXT: Symbol: MessageBoxA (1) -- 2.7.4