[MSVC] work-around for compile time issue 102513

[bd1976bris]

Disable optimizations when building clang/lib/AST/ByteCode/Interp.cpp with Microsoft's compiler as it has a bug that causes excessive build times. We do this only when NDEBUG is not defined on the assumption that building without asserts indicates that a user is strongly invested in runtime performance.

Partially addresses: #102513.

Once the bug is addressed in the Microsoft compiler this can be removed.

[llvmbot]

@llvm/pr-subscribers-clang

Author: bd1976bris (bd1976bris)

Changes

Disable optimizations when building with Microsoft's compiler as it has a bug that causes excessive build times. We do this only when NDEBUG is not defined on the assumption that building without asserts indicates that a user is strongly invested in runtime performance.

Partially addresses: #102513.

Once the bug is addressed in the Microsoft compiler this can be removed.

---

Full diff: https://github.com/llvm/llvm-project/pull/110986.diff

1 Files Affected:

• (modified) clang/lib/AST/ByteCode/Interp.cpp (+8)

diff --git a/clang/lib/AST/ByteCode/Interp.cpp b/clang/lib/AST/ByteCode/Interp.cpp
index fd9a256843a0ec..38d52e93181fbc 100644
--- a/clang/lib/AST/ByteCode/Interp.cpp
+++ b/clang/lib/AST/ByteCode/Interp.cpp
@@ -1406,6 +1406,10 @@ bool handleFixedPointOverflow(InterpState &S, CodePtr OpPC,
   return S.noteUndefinedBehavior();
 }
 
+// https://github.com/llvm/llvm-project/issues/102513
+#if defined(_WIN32) && !defined(__clang__) && !defined(NDEBUG)
+#pragma optimize("", off)
+#endif
 bool Interpret(InterpState &S, APValue &Result) {
   // The current stack frame when we started Interpret().
   // This is being used by the ops to determine wheter
@@ -1430,6 +1434,10 @@ bool Interpret(InterpState &S, APValue &Result) {
     }
   }
 }
+// https://github.com/llvm/llvm-project/issues/102513
+#if defined (_MSC_VER)
+#pragma optimize("", on)
+#endif
 
 } // namespace interp
 } // namespace clang

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[rnk]

Thanks!

[tbaederr]

Generally LGTM.

[bd1976bris]

/cherry-pick d205191

[llvmbot]

Failed to cherry-pick: d205191

https://github.com/llvm/llvm-project/actions/runs/11181614249

Please manually backport the fix and push it to your github fork. Once this is done, please create a pull request

[llvmbot]

Failed to cherry-pick: d205191

https://github.com/llvm/llvm-project/actions/runs/11181632525

Please manually backport the fix and push it to your github fork. Once this is done, please create a pull request