[clang] 33e3b2c - Fix assertion when -fasy-exception is used.

[Jennifer Yu via cfe-commits]

Author: Jennifer Yu
Date: 2023-08-10T21:54:32-07:00
New Revision: 33e3b2c46084bc47ef4067ed487b24b58934d044

URL: https://github.com/llvm/llvm-project/commit/33e3b2c46084bc47ef4067ed487b24b58934d044
DIFF: https://github.com/llvm/llvm-project/commit/33e3b2c46084bc47ef4067ed487b24b58934d044.diff

LOG: Fix assertion when -fasy-exception is used.

The assertion only happens with use of -fasy-exception without
-fexcessions.

The assertion appen during the call to generate SehScopeBegin(), where
assert with:
assert(CGF.Builder.GetInsertBlock() && InvokeDest);
InvokeDest is null. Because exceptions are disabled, and SEH is not
in use.
The fix is before call EmitSehCppScopeBegin check getInvokeDest(),
to avoid assert during the emit llvm.seh.scope.begin()

Differential Revision: https://reviews.llvm.org/D157566

Added: 
    clang/test/CodeGen/windows-seh-async-exceptions.cpp

Modified: 
    clang/lib/CodeGen/CGCleanup.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/CodeGen/CGCleanup.cpp b/clang/lib/CodeGen/CGCleanup.cpp
index 0bbab283603d98..cd51024a2b32d9 100644
--- a/clang/lib/CodeGen/CGCleanup.cpp
+++ b/clang/lib/CodeGen/CGCleanup.cpp
@@ -207,8 +207,13 @@ void *EHScopeStack::pushCleanup(CleanupKind Kind, size_t Size) {
     Scope->setLifetimeMarker();
 
   // With Windows -EHa, Invoke llvm.seh.scope.begin() for EHCleanup
+  // If exceptions are disabled/ignored and SEH is not in use, then there is no
+  // invoke destination. SEH "works" even if exceptions are off. In practice,
+  // this means that C++ destructors and other EH cleanups don't run, which is
+  // consistent with MSVC's behavior, except in the presence of -EHa.
+  // Check getInvokeDest() to generate llvm.seh.scope.begin() as needed.
   if (CGF->getLangOpts().EHAsynch && IsEHCleanup && !IsLifetimeMarker &&
-      CGF->getTarget().getCXXABI().isMicrosoft())
+      CGF->getTarget().getCXXABI().isMicrosoft() && CGF->getInvokeDest())
     CGF->EmitSehCppScopeBegin();
 
   return Scope->getCleanupBuffer();

diff  --git a/clang/test/CodeGen/windows-seh-async-exceptions.cpp b/clang/test/CodeGen/windows-seh-async-exceptions.cpp
new file mode 100644
index 00000000000000..8d78373151a00b
--- /dev/null
+++ b/clang/test/CodeGen/windows-seh-async-exceptions.cpp
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -triple x86_64-windows -fasync-exceptions -x c++ \
+// RUN:  -emit-llvm %s -o -| FileCheck %s
+
+extern "C" int printf(const char*,...);
+class PrintfArg
+{
+public:
+  PrintfArg();
+  PrintfArg(const char* s);
+
+  // compiler crash fixed if this destructor removed
+  ~PrintfArg() {int x; printf("ddd\n");  }
+};
+
+void devif_Warning(const char* fmt, PrintfArg arg1 = PrintfArg());
+// CHECK-NOT: invoke void @llvm.seh.scope.begin()
+// CHECK-NOT: invoke void @llvm.seh.scope.end()
+unsigned myfunc(unsigned index)
+{
+  devif_Warning("");
+  return 0;
+}