[PATCH] D99259: [WebAssembly] Don't inline -emscripten-cxx-exceptions-allowed functions

[Heejin Ahn via Phabricator via cfe-commits]

aheejin created this revision.
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Functions specified in `-emscripten-cxx-exceptions-allowed`, which is
set by Emscripten's `EXCEPTION_CATCHING_ALLOWED` setting, can be inlined
in LLVM middle ends before we reach WebAssemblyLowerEmscriptenEHSjLj
pass in the wasm backend and thus don't get transformed for exception
catching.

This fixes the issue by adding `--force-attribute=FUNC_NAME:noinline`
for each function name in `-emscripten-cxx-exceptions-allowed`, which
adds `noinline` attribute to the specified function and thus excludes
the function from inlining candidates in optimization passes.

Fixes the remaining half of
https://github.com/emscripten-core/emscripten/issues/10721.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D99259

Files:
  clang/lib/Driver/ToolChains/WebAssembly.cpp
  clang/test/Driver/wasm-toolchain.c


Index: clang/test/Driver/wasm-toolchain.c
===================================================================
--- clang/test/Driver/wasm-toolchain.c
+++ clang/test/Driver/wasm-toolchain.c
@@ -79,6 +79,21 @@
 // RUN:   | FileCheck -check-prefix=PTHREAD_NO_SIGN_EXT %s
 // PTHREAD_NO_SIGN_EXT: invalid argument '-pthread' not allowed with '-mno-sign-ext'
 
+// '-mllvm -emscripten-cxx-exceptions-allowed=foo,bar' sets
+// '-mllvm --force-attribute=foo:noinline -mllvm --force-attribute=bar:noinline'
+// RUN: %clang -### -no-canonical-prefixes -target wasm32-unknown-unknown \
+// RUN:    --sysroot=/foo %s -mllvm -enable-emscripten-cxx-exceptions \
+// RUN:    -mllvm -emscripten-cxx-exceptions-allowed=foo,bar 2>&1 \
+// RUN:  | FileCheck -check-prefix=EMSCRIPTEN_EH_ALLOWED_NOINLINE %s
+// EMSCRIPTEN_EH_ALLOWED_NOINLINE: clang{{.*}}" "-cc1" {{.*}} "-mllvm" "--force-attribute=foo:noinline" "-mllvm" "--force-attribute=bar:noinline"
+
+// '-mllvm -emscripten-cxx-exceptions-allowed' only allowed with
+// '-mllvm -enable-emscripten-cxx-exceptions'
+// RUN: %clang -### -no-canonical-prefixes -target wasm32-unknown-unknown \
+// RUN:     --sysroot=/foo %s -mllvm -emscripten-cxx-exceptions-allowed 2>&1 \
+// RUN:   | FileCheck -check-prefix=EMSCRIPTEN_EH_ALLOWED_WO_ENABLE %s
+// EMSCRIPTEN_EH_ALLOWED_WO_ENABLE: invalid argument '-mllvm -emscripten-cxx-exceptions-allowed' only allowed with '-mllvm -enable-emscripten-cxx-exceptions'
+
 // '-fwasm-exceptions' sets +exception-handling
 // RUN: %clang -### -no-canonical-prefixes -target wasm32-unknown-unknown \
 // RUN:    --sysroot=/foo %s -fwasm-exceptions 2>&1 \
Index: clang/lib/Driver/ToolChains/WebAssembly.cpp
===================================================================
--- clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -294,6 +294,33 @@
     CC1Args.push_back("-target-feature");
     CC1Args.push_back("+exception-handling");
   }
+
+  for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {
+    StringRef Opt = A->getValue(0);
+    if (Opt.startswith("-emscripten-cxx-exceptions-allowed")) {
+      // '-mllvm -emscripten-cxx-exceptions-allowed' is only allowed with
+      // '-mllvm -enable-emscripten-cxx-exceptions'
+      bool EmExceptionArgExists = false;
+      for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm))
+        if (StringRef(A->getValue(0)) == "-enable-emscripten-cxx-exceptions")
+          EmExceptionArgExists = true;
+      if (!EmExceptionArgExists)
+        getDriver().Diag(diag::err_drv_argument_only_allowed_with)
+            << "-mllvm -emscripten-cxx-exceptions-allowed"
+            << "-mllvm -enable-emscripten-cxx-exceptions";
+
+      // Prevent functions specified in -emscripten-cxx-exceptions-allowed list
+      // from being inlined before reaching the wasm backend.
+      StringRef FuncNamesStr = Opt.split('=').second;
+      SmallVector<StringRef, 4> FuncNames;
+      FuncNamesStr.split(FuncNames, ',');
+      for (auto Name : FuncNames) {
+        CC1Args.push_back("-mllvm");
+        CC1Args.push_back(DriverArgs.MakeArgString("--force-attribute=" + Name +
+                                                   ":noinline"));
+      }
+    }
+  }
 }
 
 ToolChain::RuntimeLibType WebAssembly::GetDefaultRuntimeLibType() const {


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