[clang] 25825d4 - [WebAssembly] Enable Wasm EH features only once (#124042)

[via cfe-commits]

Author: Heejin Ahn
Date: 2025-01-23T14:47:15-08:00
New Revision: 25825d4ac9683010b0b921924cd5e244a82db1a3

URL: https://github.com/llvm/llvm-project/commit/25825d4ac9683010b0b921924cd5e244a82db1a3
DIFF: https://github.com/llvm/llvm-project/commit/25825d4ac9683010b0b921924cd5e244a82db1a3.diff

LOG: [WebAssembly] Enable Wasm EH features only once (#124042)

#122466 had an unexpected side effect that,
`EnableFeaturesForWasmEHSjLj` and `BanIncompatibleOptionsForWasmEHSjLj`
can be called multiple times now, every time a Wasm EH flag
(`-fwasm-exceptions`, `-wasm-enable-eh`, `-wasm-enable-sjlj`, ..) was
checked and handled. This resulted in unnecessarily adding the same
feature-enabling arguments multiple times to the command line, for
example, `-target-feature +exception-handling` could be added as many as
three times, which didn't cause any errors but unnecessary. Also we ran
`BanIncompatibleOptionsForWasmEHSjLj` more than once, which was harmless
but unnecessary.

This guards these functions with a static variable so that we only run
them once.

Added: 
    

Modified: 
    clang/lib/Driver/ToolChains/WebAssembly.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Driver/ToolChains/WebAssembly.cpp b/clang/lib/Driver/ToolChains/WebAssembly.cpp
index 10f9a4f338f8f1..eebe3becada657 100644
--- a/clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ b/clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -347,6 +347,9 @@ void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
   // Bans incompatible options for Wasm EH / SjLj. We don't allow using
   // 
diff erent modes for EH and SjLj.
   auto BanIncompatibleOptionsForWasmEHSjLj = [&](StringRef CurOption) {
+    static bool HasRun = false;
+    if (HasRun)
+      return;
     if (DriverArgs.hasFlag(options::OPT_mno_exception_handing,
                            options::OPT_mexception_handing, false))
       getDriver().Diag(diag::err_drv_argument_not_allowed_with)
@@ -370,10 +373,14 @@ void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
               << CurOption << Option;
       }
     }
+    HasRun = true;
   };
 
   // Enable necessary features for Wasm EH / SjLj in the backend.
   auto EnableFeaturesForWasmEHSjLj = [&]() {
+    static bool HasRun = false;
+    if (HasRun)
+      return;
     CC1Args.push_back("-target-feature");
     CC1Args.push_back("+exception-handling");
     // The standardized Wasm EH spec requires multivalue and reference-types.
@@ -383,6 +390,7 @@ void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
     CC1Args.push_back("+reference-types");
     // Backend needs '-exception-model=wasm' to use Wasm EH instructions
     CC1Args.push_back("-exception-model=wasm");
+    HasRun = true;
   };
 
   if (DriverArgs.getLastArg(options::OPT_fwasm_exceptions)) {