[clang] d1aca0a - [WebAssembly] Define __WASM_EXCEPTIONS__ for -fwasm-exceptions (#92604)

[via cfe-commits]

Author: Heejin Ahn
Date: 2024-05-20T18:43:13-07:00
New Revision: d1aca0ae2e0c52298966e35e4312e21045d4c6e4

URL: https://github.com/llvm/llvm-project/commit/d1aca0ae2e0c52298966e35e4312e21045d4c6e4
DIFF: https://github.com/llvm/llvm-project/commit/d1aca0ae2e0c52298966e35e4312e21045d4c6e4.diff

LOG: [WebAssembly] Define __WASM_EXCEPTIONS__ for -fwasm-exceptions (#92604)

When using other specific exception options in Clang, such as
`-fseh-exceptions` or `-fsjlj-exceptions`, Clang defines a corresponding
preprocessor such as `-D__USING_SJLJ_EXCEPTIONS__`. Emscripten does that
in our own build system:

https://github.com/emscripten-core/emscripten/blob/7dcd7f40749918e141dc33397d2f4311dd80637a/tools/system_libs.py#L1577-L1578

But to make Wasm EH usable in non-Emscripten toolchain, this has to be
defined somewhere else. This PR makes Wasm EH consistent with other
exception scheme by letting it defined by Clang depending on the
exception option.

We have been using `__USING_WASM_EXCEPTIONS__` in our current library
code, but this changes it to `__WASM_EXCEPTIONS__` for its conciseness,
and I will update other parts of LLVM as follow-ups. This does not break
anything currently working, because we have not been defining anything
in Clang so far.

Added: 
    

Modified: 
    clang/lib/Frontend/InitPreprocessor.cpp
    clang/test/CodeGenCXX/wasm-eh.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index c1d209466ffe5..68760e00003e0 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -1006,6 +1006,8 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   else if (LangOpts.hasDWARFExceptions() &&
            (TI.getTriple().isThumb() || TI.getTriple().isARM()))
     Builder.defineMacro("__ARM_DWARF_EH__");
+  else if (LangOpts.hasWasmExceptions() && TI.getTriple().isWasm())
+    Builder.defineMacro("__WASM_EXCEPTIONS__");
 
   if (LangOpts.Deprecated)
     Builder.defineMacro("__DEPRECATED");

diff  --git a/clang/test/CodeGenCXX/wasm-eh.cpp b/clang/test/CodeGenCXX/wasm-eh.cpp
index 1b17498ba9ce9..9dc15633bfed9 100644
--- a/clang/test/CodeGenCXX/wasm-eh.cpp
+++ b/clang/test/CodeGenCXX/wasm-eh.cpp
@@ -1,4 +1,8 @@
 // REQUIRES: webassembly-registered-target
+
+// RUN: %clang -E -dM %s -target wasm32-unknown-unknown -fwasm-exceptions | FileCheck %s -check-prefix PREPROCESSOR
+// PREPROCESSOR: #define __WASM_EXCEPTIONS__ 1
+
 // RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -mllvm -wasm-enable-eh -exception-model=wasm -target-feature +exception-handling -emit-llvm -o - -std=c++11 | FileCheck %s
 // RUN: %clang_cc1 %s -triple wasm64-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -mllvm -wasm-enable-eh -exception-model=wasm -target-feature +exception-handling -emit-llvm -o - -std=c++11 | FileCheck %s