Object: account for short output names

[compnerd]

The import library thunk name suffix uses the stem of the file. We currently would attempt to trim the suffix by dropping the trailing 4 characters (under the assumption that the output name was .lib). This now uses the llvm::sys::path API for computing the stem. This avoids an assertion failure when the name is less the 4 characters and assertions are enabled.

[llvmbot]

@llvm/pr-subscribers-llvm-binary-utilities

@llvm/pr-subscribers-lld-coff

Changes

The import library thunk name suffix uses the stem of the file. We currently would attempt to trim the suffix by dropping the trailing 4 characters (under the assumption that the output name was .lib). This now uses the llvm::sys::path API for computing the stem. This avoids an assertion failure when the name is less the 4 characters and assertions are enabled.

Full diff: https://github.com/llvm/llvm-project/pull/66532.diff

2 Files Affected:

• (modified) lld/test/COFF/implib-name.test (+1)
• (modified) llvm/lib/Object/COFFImportFile.cpp (+1-1)

diff --git a/lld/test/COFF/implib-name.test b/lld/test/COFF/implib-name.test
index 4a875ab24b74387..3ec8d823a91da15 100644
--- a/lld/test/COFF/implib-name.test
+++ b/lld/test/COFF/implib-name.test
@@ -70,3 +70,4 @@ CHECK-NODEF-DLL: default.dll
 CHECK-NODEF-DLL: default.dll
 CHECK-NODEF-DLL: default.dll
 
+# RUN: lld-link /nologo /machine:x64 /out:%T/exe %T/object.obj /entry:f /subsystem:CONSOLE
diff --git a/llvm/lib/Object/COFFImportFile.cpp b/llvm/lib/Object/COFFImportFile.cpp
index 5e3508ba34aec5a..0e99fc9373e0db7 100644
--- a/llvm/lib/Object/COFFImportFile.cpp
+++ b/llvm/lib/Object/COFFImportFile.cpp
@@ -140,7 +140,7 @@ class ObjectFactory {
 
 public:
   ObjectFactory(StringRef S, MachineTypes M)
-      : Machine(M), ImportName(S), Library(S.drop_back(4)),
+      : Machine(M), ImportName(S), Library(llvm::sys::path::stem(S)),
         ImportDescriptorSymbolName(("__IMPORT_DESCRIPTOR_" + Library).str()),
         NullThunkSymbolName(("\x7f" + Library + "_NULL_THUNK_DATA").str()) {}