[clang] Default to -fno-sized-deallocation for AIX

[xingxue-ibm]

Some libc++ LIT test cases and user code define their own version of operator delete that are not sized. With -fno-sized-deallocation, destructors call the non-sized operator delete and it will be resolved to the user defined version. However, with -fsized-deallocation, destructors will call the sized operator delete which will be resolved to the weak definition in libc++abi because the user code does not define the corresponding sized version. The libc++abi sized operator delete in turn calls the non-sized version of operator delete of the same shared object inside libc++abi instead of the user defined version on AIX because runtime linking is not the default for AIX and therefore, fails the tests or user code. This patch sets -fno-sized-deallocation as the default for AIX if neither -fsize-deallocation nor -fno-sized-deallocation is explicitly set, similar to what is done for ZOS.

[llvmbot]

@llvm/pr-subscribers-backend-powerpc
@llvm/pr-subscribers-clang-driver

@llvm/pr-subscribers-clang

Author: Xing Xue (xingxue-ibm)

Changes

Some libc++ LIT test cases and user code define their own version of operator delete that are not sized. With -fno-sized-deallocation, destructors call the non-sized operator delete and it will be resolved to the user defined version. However, with -fsized-deallocation, destructors will call the sized operator delete which will be resolved to the weak definition in libc++abi because the user code does not define the corresponding sized version. The libc++abi sized operator delete in turn calls the non-sized version of operator delete of the same shared object inside libc++abi instead of the user defined version on AIX because runtime linking is not the default for AIX and therefore, fails the tests or user code. This patch sets -fno-sized-deallocation as the default for AIX if neither -fsize-deallocation nor -fno-sized-deallocation is explicitly set, similar to what is done for ZOS.

---

Full diff: https://github.com/llvm/llvm-project/pull/97076.diff

2 Files Affected:

• (modified) clang/lib/Driver/ToolChains/AIX.cpp (+6)
• (modified) clang/unittests/StaticAnalyzer/CallEventTest.cpp (+4)

diff --git a/clang/lib/Driver/ToolChains/AIX.cpp b/clang/lib/Driver/ToolChains/AIX.cpp
index 381d72e045b95..b04502a57a9f7 100644
--- a/clang/lib/Driver/ToolChains/AIX.cpp
+++ b/clang/lib/Driver/ToolChains/AIX.cpp
@@ -551,6 +551,12 @@ void AIX::addClangTargetOptions(
   if (Args.hasFlag(options::OPT_fxl_pragma_pack,
                    options::OPT_fno_xl_pragma_pack, true))
     CC1Args.push_back("-fxl-pragma-pack");
+
+  // Pass "-fno-sized-deallocation" only when the user hasn't manually enabled
+  // or disabled sized deallocations.
+  if (!Args.getLastArgNoClaim(options::OPT_fsized_deallocation,
+                              options::OPT_fno_sized_deallocation))
+    CC1Args.push_back("-fno-sized-deallocation");
 }
 
 void AIX::addProfileRTLibs(const llvm::opt::ArgList &Args,
diff --git a/clang/unittests/StaticAnalyzer/CallEventTest.cpp b/clang/unittests/StaticAnalyzer/CallEventTest.cpp
index 7c4132788ca7e..de28bb158ef66 100644
--- a/clang/unittests/StaticAnalyzer/CallEventTest.cpp
+++ b/clang/unittests/StaticAnalyzer/CallEventTest.cpp
@@ -76,7 +76,11 @@ TEST(CXXDeallocatorCall, SimpleDestructor) {
     }
   )",
                                                          Diags));
+#if !defined(__cpp_sized_deallocation)
+  EXPECT_EQ(Diags, "test.CXXDeallocator: NumArgs: 1\n");
+#else
   EXPECT_EQ(Diags, "test.CXXDeallocator: NumArgs: 2\n");
+#endif
 }
 
 } // namespace

[wangpc-pp]

LGTM.