Raise error if trying to use Windows hotpatching on non-Windows OS

Author: sivadeilra

clang/lib/CodeGen/CodeGenModule.cpp

@@ -456,8 +456,7 @@ CodeGenModule::CodeGenModule(ASTContext &C,
 
   // If there are any functions that are marked for Windows hot-patching,
   // then build the list of functions now.
-  if (!CGO.MSHotPatchFunctionsFile.empty() ||
-      !CGO.MSHotPatchFunctionsList.empty()) {
+  if (M.getTargetTriple().isOSBinFormatCOFF()) {
     if (!CGO.MSHotPatchFunctionsFile.empty()) {
       auto BufOrErr = llvm::MemoryBuffer::getFile(CGO.MSHotPatchFunctionsFile);
       if (BufOrErr) {
@@ -486,6 +485,22 @@ CodeGenModule::CodeGenModule(ASTContext &C,
 
     std::sort(this->MSHotPatchFunctions.begin(),
               this->MSHotPatchFunctions.end());
+  } else {
+    if (!CGO.MSHotPatchFunctionsFile.empty()) {
+      unsigned DiagID = diags.getCustomDiagID(
+          DiagnosticsEngine::Error,
+          "hotpatch functions file (-fms-hotpatch-functions-file) is only "
+          "supported on Windows targets");
+      diags.Report(DiagID);
+    }
+
+    if (!CGO.MSHotPatchFunctionsList.empty()) {
+      unsigned DiagID = diags.getCustomDiagID(
+          DiagnosticsEngine::Error,
+          "hotpatch functions list (-fms-hotpatch-functions-list) is only "
+          "supported on Windows targets");
+      diags.Report(DiagID);
+    }
   }
 }
 

clang/test/CodeGen/ms-hotpatch-bad-os.c

@@ -0,0 +1,7 @@
+// This verifies that enabling Windows hotpatching when targeting a non-Windows OS causes an error.
+//
+// RUN: not %clang -c --target=x86_64-unknown-linux-elf -fms-hotpatch -fms-hotpatch-functions-list=foo -fms-hotpatch-functions-file=this_will_never_be_accessed -o%t.o %s 2>&1 | FileCheck %s
+// CHECK: hotpatch functions file (-fms-hotpatch-functions-file) is only supported on Windows targets
+// CHECK: hotpatch functions list (-fms-hotpatch-functions-list) is only supported on Windows targets
+
+void foo();

llvm/lib/CodeGen/TargetPassConfig.cpp

@@ -894,8 +894,7 @@ void TargetPassConfig::addIRPasses() {
   if (EnableGlobalMergeFunc)
     addPass(createGlobalMergeFuncPass());
 
-  if (TM->getTargetTriple().isOSBinFormatCOFF())
-    addPass(createWindowsHotPatch());
+  addPass(createWindowsHotPatch());
 }
 
 /// Turn exception handling constructs into something the code generators can

llvm/lib/CodeGen/WindowsHotPatch.cpp

@@ -84,6 +84,35 @@ ModulePass *llvm::createWindowsHotPatch() { return new WindowsHotPatch(); }
 // Find functions marked with Attribute::MarkedForWindowsHotPatching and modify
 // their code (if necessary) to account for accesses to global variables.
 bool WindowsHotPatch::runOnModule(Module &M) {
+  // If the target OS is not Windows, then check that there are no functions
+  // marked for Windows hot-patching.
+  if (!M.getTargetTriple().isOSBinFormatCOFF()) {
+    if (!LLVMMSHotPatchFunctionsFile.empty()) {
+      M.getContext().diagnose(llvm::DiagnosticInfoGeneric{
+          llvm::Twine("--ms-hotpatch-functions-file is only supported when "
+                      "target OS is Windows")});
+    }
+
+    if (!LLVMMSHotPatchFunctionsList.empty()) {
+      M.getContext().diagnose(llvm::DiagnosticInfoGeneric{
+          llvm::Twine("--ms-hotpatch-functions-list is only supported when "
+                      "target OS is Windows")});
+    }
+
+    // Functions may have already been marked for hot-patching by the front-end.
+    // Check for any functions marked for hot-patching and report an error if
+    // any are found.
+    for (auto &F : M.functions()) {
+      if (F.hasFnAttribute(Attribute::MarkedForWindowsHotPatching)) {
+        M.getContext().diagnose(llvm::DiagnosticInfoGeneric{
+            llvm::Twine("function is marked for Windows hot-patching, but the "
+                        "target OS is not Windows: ") +
+            F.getName()});
+      }
+    }
+    return false;
+  }
+
   // The front end may have already marked functions for hot-patching. However,
   // we also allow marking functions by passing -ms-hotpatch-functions-file or
   // -ms-hotpatch-functions-list directly to LLVM. This allows hot-patching to

llvm/test/CodeGen/Generic/ms-hotpatch-bad-os.ll

@@ -0,0 +1,17 @@
+; This tests directly annotating a function with marked_for_windows_hot_patching, but on the wrong target OS.
+;
+; RUN: not llc -mtriple=x86_64-unknown-linux --ms-hotpatch-functions-list=this_never_gets_used --ms-hotpatch-functions-file=this_never_gets_used < %s 2>&1 | FileCheck %s
+;
+; CHECK: error: --ms-hotpatch-functions-file is only supported when target OS is Windows
+; CHECK: error: --ms-hotpatch-functions-list is only supported when target OS is Windows
+; CHECK: error: function is marked for Windows hot-patching, but the target OS is not Windows: this_gets_hotpatched
+
+source_filename = ".\\ms-hotpatch-bad-os.ll"
+target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux"
+
+define noundef i32 @this_gets_hotpatched() #0 {
+    ret i32 0
+}
+
+attributes #0 = { marked_for_windows_hot_patching mustprogress noinline nounwind optnone uwtable }

llvm/test/CodeGen/Generic/ms-hotpatch-functions-file.ll

@@ -1,6 +1,7 @@
 ; This tests annotating a function with marked_for_windows_hot_patching by using --ms-hotpatch-functions-file.
 ;
-; RUN: llc -mtriple=x86_64-windows --ms-hotpatch-functions-file=%S/ms-hotpatch-functions-file.txt < %s | FileCheck %s
+; RUN: echo this_gets_hotpatched > %t.ms-hotpatch-functions-file.txt
+; RUN: llc -mtriple=x86_64-windows --ms-hotpatch-functions-file=%t.ms-hotpatch-functions-file.txt < %s | FileCheck %s
 
 source_filename = ".\\ms-hotpatch-functions-file.ll"
 target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"