[llvm] [Windows] Use absolute path when loading system shared library (PR #90520)

[via llvm-commits]

https://github.com/jofrn updated https://github.com/llvm/llvm-project/pull/90520

>From 4c78b147d8cc7682cfacb8a206b472b04a3a5c21 Mon Sep 17 00:00:00 2001
From: jofernau <jofernau at amd.com>
Date: Mon, 29 Apr 2024 13:17:40 -0700
Subject: [PATCH 1/2] [Windows] Find absolute path to dll

---
 llvm/lib/Support/CMakeLists.txt      | 16 ++++++++++++++++
 llvm/lib/Support/Windows/Signals.inc |  9 ++++++---
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
index 03e888958a0711..46a9ffea50fc39 100644
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -41,6 +41,22 @@ if( MSVC OR MINGW )
   # libuuid required for FOLDERID_Profile usage in lib/Support/Windows/Path.inc.
   # advapi32 required for CryptAcquireContextW in lib/Support/Windows/Path.inc.
   set(system_libs ${system_libs} psapi shell32 ole32 uuid advapi32 ws2_32)
+  # find dbgcore.dll and dbghelp.dll together in their system folder,
+  # required for lib/Support/Windows/Signals.inc.
+  set(tempsuffixes ${CMAKE_FIND_LIBRARY_SUFFIXES})
+  set(CMAKE_FIND_LIBRARY_SUFFIXES .DLL ${CMAKE_FIND_LIBRARY_SUFFIXES})
+  find_library(DBGCORE dbgcore REQUIRED NO_CACHE)
+  cmake_path(GET DBGCORE PARENT_PATH DBGSYSPATH)
+  find_library(DBGHELP dbghelp REQUIRED HINTS "${DBGSYSPATH}" NO_DEFAULT_PATH NO_CACHE)
+  cmake_path(CONVERT "${DBGCORE}" TO_NATIVE_PATH_LIST DBGCORE)
+  cmake_path(CONVERT "${DBGHELP}" TO_NATIVE_PATH_LIST DBGHELP)
+  string(REPLACE "\\" "\\\\" DBGCORE "${DBGCORE}")
+  string(REPLACE "\\" "\\\\" DBGHELP "${DBGHELP}")
+  message("-DDBGCORE is ${DBGCORE}")
+  message("-DDBGHELP is ${DBGHELP}")
+  add_compile_definitions(DBGCOREDLL="${DBGCORE}"
+                          DBGHELPDLL="${DBGHELP}")
+  set(CMAKE_FIND_LIBRARY_SUFFIXES ${tempsuffixes})
 elseif( CMAKE_HOST_UNIX )
   if( HAVE_LIBRT )
     set(system_libs ${system_libs} rt)
diff --git a/llvm/lib/Support/Windows/Signals.inc b/llvm/lib/Support/Windows/Signals.inc
index 34635b5aba7a1b..c4cfc19553b9ad 100644
--- a/llvm/lib/Support/Windows/Signals.inc
+++ b/llvm/lib/Support/Windows/Signals.inc
@@ -168,10 +168,13 @@ static bool isDebugHelpInitialized() {
 }
 
 static bool load64BitDebugHelp(void) {
-  HMODULE hLib = ::LoadLibraryW(L"Dbghelp.dll");
-  if (hLib) {
+  HMODULE hLibCore = ::LoadLibraryW(L"" DBGCOREDLL);
+  if (hLibCore) {
     fMiniDumpWriteDump =
-        (fpMiniDumpWriteDump)::GetProcAddress(hLib, "MiniDumpWriteDump");
+        (fpMiniDumpWriteDump)::GetProcAddress(hLibCore, "MiniDumpWriteDump");
+  }
+  HMODULE hLib = ::LoadLibraryW(L"" DBGHELPDLL);
+  if (hLib) {
     fStackWalk64 = (fpStackWalk64)::GetProcAddress(hLib, "StackWalk64");
     fSymGetModuleBase64 =
         (fpSymGetModuleBase64)::GetProcAddress(hLib, "SymGetModuleBase64");

>From 501b15280cdba7aaa8a63b2d7300074af4db8686 Mon Sep 17 00:00:00 2001
From: jofernau <jofernau at amd.com>
Date: Mon, 29 Apr 2024 15:40:01 -0700
Subject: [PATCH 2/2] [Windows] Restrict search path of LoadLibraryW.

LoadLibraryW search will be more portable than searching during buildtime. This modifies its search set to omit the current directory.
---
 llvm/lib/Support/CMakeLists.txt      | 16 ----------------
 llvm/lib/Support/InitLLVM.cpp        |  4 ++++
 llvm/lib/Support/Windows/Signals.inc |  4 ++--
 3 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
index 46a9ffea50fc39..03e888958a0711 100644
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -41,22 +41,6 @@ if( MSVC OR MINGW )
   # libuuid required for FOLDERID_Profile usage in lib/Support/Windows/Path.inc.
   # advapi32 required for CryptAcquireContextW in lib/Support/Windows/Path.inc.
   set(system_libs ${system_libs} psapi shell32 ole32 uuid advapi32 ws2_32)
-  # find dbgcore.dll and dbghelp.dll together in their system folder,
-  # required for lib/Support/Windows/Signals.inc.
-  set(tempsuffixes ${CMAKE_FIND_LIBRARY_SUFFIXES})
-  set(CMAKE_FIND_LIBRARY_SUFFIXES .DLL ${CMAKE_FIND_LIBRARY_SUFFIXES})
-  find_library(DBGCORE dbgcore REQUIRED NO_CACHE)
-  cmake_path(GET DBGCORE PARENT_PATH DBGSYSPATH)
-  find_library(DBGHELP dbghelp REQUIRED HINTS "${DBGSYSPATH}" NO_DEFAULT_PATH NO_CACHE)
-  cmake_path(CONVERT "${DBGCORE}" TO_NATIVE_PATH_LIST DBGCORE)
-  cmake_path(CONVERT "${DBGHELP}" TO_NATIVE_PATH_LIST DBGHELP)
-  string(REPLACE "\\" "\\\\" DBGCORE "${DBGCORE}")
-  string(REPLACE "\\" "\\\\" DBGHELP "${DBGHELP}")
-  message("-DDBGCORE is ${DBGCORE}")
-  message("-DDBGHELP is ${DBGHELP}")
-  add_compile_definitions(DBGCOREDLL="${DBGCORE}"
-                          DBGHELPDLL="${DBGHELP}")
-  set(CMAKE_FIND_LIBRARY_SUFFIXES ${tempsuffixes})
 elseif( CMAKE_HOST_UNIX )
   if( HAVE_LIBRT )
     set(system_libs ${system_libs} rt)
diff --git a/llvm/lib/Support/InitLLVM.cpp b/llvm/lib/Support/InitLLVM.cpp
index b7e463a19122db..8f4b765e7b5561 100644
--- a/llvm/lib/Support/InitLLVM.cpp
+++ b/llvm/lib/Support/InitLLVM.cpp
@@ -43,6 +43,10 @@ InitLLVM::InitLLVM(int &Argc, const char **&Argv,
   assert(!Initialized && "InitLLVM was already initialized!");
   Initialized = true;
 #endif
+#ifdef _WIN32
+  // Avoid searching the directory from which the application is loaded.
+  SetDllDirectoryA("");
+#endif
 #ifdef __MVS__
   // Bring stdin/stdout/stderr into a known state.
   sys::AddSignalHandler(CleanupStdHandles, nullptr);
diff --git a/llvm/lib/Support/Windows/Signals.inc b/llvm/lib/Support/Windows/Signals.inc
index c4cfc19553b9ad..2f4d1951d78f2b 100644
--- a/llvm/lib/Support/Windows/Signals.inc
+++ b/llvm/lib/Support/Windows/Signals.inc
@@ -168,12 +168,12 @@ static bool isDebugHelpInitialized() {
 }
 
 static bool load64BitDebugHelp(void) {
-  HMODULE hLibCore = ::LoadLibraryW(L"" DBGCOREDLL);
+  HMODULE hLibCore = ::LoadLibraryW(L"Dbgcore.dll");
   if (hLibCore) {
     fMiniDumpWriteDump =
         (fpMiniDumpWriteDump)::GetProcAddress(hLibCore, "MiniDumpWriteDump");
   }
-  HMODULE hLib = ::LoadLibraryW(L"" DBGHELPDLL);
+  HMODULE hLib = ::LoadLibraryW(L"Dbghelp.dll");
   if (hLib) {
     fStackWalk64 = (fpStackWalk64)::GetProcAddress(hLib, "StackWalk64");
     fSymGetModuleBase64 =