WebAssembly: Remove -wasm-enable-eh cl::opt in favor of -exception-model=wasm by arsenm · Pull Request #224313 · llvm/llvm-project

arsenm · 2026-09-17T13:58:53Z

The -wasm-enable-eh backend flag was redundant with -exception-model=wasm:
every caller paired the two, and the model already carries the intent.

Co-authored-by: Claude (Claude-Opus-4.8) noreply@anthropic.com

…del=wasm The -wasm-enable-eh backend flag was redundant with -exception-model=wasm: every caller paired the two, and the model already carries the intent. Co-authored-by: Claude (Claude-Opus-4.8) <noreply@anthropic.com>

arsenm · 2026-09-17T13:59:10Z

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llvmorg-github-actions · 2026-09-17T13:59:56Z

@llvm/pr-subscribers-clang-driver

@llvm/pr-subscribers-backend-webassembly

Author: Matt Arsenault (arsenm)

Changes

The -wasm-enable-eh backend flag was redundant with -exception-model=wasm:
every caller paired the two, and the model already carries the intent.

Co-authored-by: Claude (Claude-Opus-4.8) <noreply@anthropic.com>

Patch is 40.05 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/224313.diff

28 Files Affected:

(modified) clang/lib/Driver/ToolChains/WebAssembly.cpp (+1-5)
(removed) clang/test/CodeGen/WebAssembly/exception-model-flag.c (-16)
(modified) clang/test/CodeGen/WebAssembly/wasm-exception-model-flag-parse-ir-input.ll (+1-1)
(modified) clang/test/CodeGen/exception-model-flag.c (+8)
(modified) clang/test/CodeGenCXX/builtins-eh-wasm.cpp (+1-1)
(modified) clang/test/CodeGenCXX/wasm-eh.cpp (+6-6)
(modified) clang/test/CodeGenObjC/wasm32-eh-arc.m (+1-1)
(modified) clang/test/CodeGenObjC/wasm32-eh.m (+1-1)
(modified) clang/test/CodeGenObjCXX/wasm32-eh-objcxx.mm (+1-1)
(modified) clang/test/Driver/wasm-toolchain.c (+2-2)
(modified) llvm/lib/Target/WebAssembly/WebAssemblyCodeGenPassBuilder.cpp (+2-3)
(modified) llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp (+5-21)
(modified) llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.h (-1)
(modified) llvm/test/CodeGen/WebAssembly/cfg-stackify-eh-legacy.ll (+5-5)
(modified) llvm/test/CodeGen/WebAssembly/cfg-stackify-eh-legacy.mir (+1-1)
(modified) llvm/test/CodeGen/WebAssembly/cfg-stackify-eh.ll (+5-5)
(modified) llvm/test/CodeGen/WebAssembly/eh-lsda.ll (+6-6)
(modified) llvm/test/CodeGen/WebAssembly/eh-option-errors.ll (+1-7)
(modified) llvm/test/CodeGen/WebAssembly/exception-legacy.ll (+3-3)
(modified) llvm/test/CodeGen/WebAssembly/exception-legacy.mir (+1-1)
(modified) llvm/test/CodeGen/WebAssembly/exception.ll (+5-5)
(modified) llvm/test/CodeGen/WebAssembly/lower-wasm-ehsjlj-phi.ll (+1-1)
(modified) llvm/test/CodeGen/WebAssembly/lower-wasm-ehsjlj.ll (+2-2)
(modified) llvm/test/CodeGen/WebAssembly/null-streamer.ll (+2-2)
(modified) llvm/test/CodeGen/WebAssembly/wasm-eh-em-sjlj-error.ll (+1-1)
(modified) llvm/test/CodeGen/WebAssembly/wasm-eh-invalid-personality.ll (+1-1)
(modified) llvm/test/CodeGen/WebAssembly/wasm-eh-prepare.ll (+1-1)
(modified) llvm/test/CodeGen/WebAssembly/wasm-eh-sjlj-setjmp-within-catch.ll (+1-1)

diff --git a/clang/lib/Driver/ToolChains/WebAssembly.cpp b/clang/lib/Driver/ToolChains/WebAssembly.cpp
index b28154772f9f9..4487798b85fcc 100644
--- a/clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ b/clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -456,9 +456,6 @@ void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
   if (DriverArgs.getLastArg(options::OPT_fwasm_exceptions)) {
     BanIncompatibleOptionsForWasmEHSjLj("-fwasm-exceptions");
     EnableFeaturesForWasmEHSjLj();
-    // Backend needs -wasm-enable-eh to enable Wasm EH
-    CC1Args.push_back("-mllvm");
-    CC1Args.push_back("-wasm-enable-eh");
   }
 
   for (const Arg *A : DriverArgs.filtered(options::OPT_mllvm)) {
@@ -483,8 +480,7 @@ void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
       }
     }
 
-    for (const auto *Option :
-         {"-wasm-enable-eh", "-wasm-enable-sjlj", "-wasm-use-legacy-eh"}) {
+    for (const auto *Option : {"-wasm-enable-sjlj", "-wasm-use-legacy-eh"}) {
       if (Opt.starts_with(Option)) {
         BanIncompatibleOptionsForWasmEHSjLj(Option);
         EnableFeaturesForWasmEHSjLj();
diff --git a/clang/test/CodeGen/WebAssembly/exception-model-flag.c b/clang/test/CodeGen/WebAssembly/exception-model-flag.c
deleted file mode 100644
index 35b56db409b0b..0000000000000
--- a/clang/test/CodeGen/WebAssembly/exception-model-flag.c
+++ /dev/null
@@ -1,16 +0,0 @@
-// REQUIRES: webassembly-registered-target
-
-// Verify clang records the "exception-model" module flag for the WebAssembly
-// exception models. The target-independent models are covered in
-// exception-model-flag.c.
-
-// Wasm EH (needs the backend enable flag) records the "wasm" model.
-// RUN: %clang_cc1 -triple wasm32-unknown-unknown -fexceptions -exception-model=wasm -mllvm -wasm-enable-eh -emit-llvm %s -o - | FileCheck %s --check-prefix=WASM
-
-// Emscripten EH records the "emscripten" model.
-// RUN: %clang_cc1 -triple wasm32-unknown-emscripten -fexceptions -exception-model=emscripten -emit-llvm %s -o - | FileCheck %s --check-prefix=EMSCRIPTEN
-
-void f(void) {}
-
-// WASM: !{i32 1, !"exception-model", !"wasm"}
-// EMSCRIPTEN: !{i32 1, !"exception-model", !"emscripten"}
diff --git a/clang/test/CodeGen/WebAssembly/wasm-exception-model-flag-parse-ir-input.ll b/clang/test/CodeGen/WebAssembly/wasm-exception-model-flag-parse-ir-input.ll
index 8263c98670aab..1410de231660a 100644
--- a/clang/test/CodeGen/WebAssembly/wasm-exception-model-flag-parse-ir-input.ll
+++ b/clang/test/CodeGen/WebAssembly/wasm-exception-model-flag-parse-ir-input.ll
@@ -2,7 +2,7 @@
 
 ; Check all the options parse
 ; RUN: %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=none %s | FileCheck %s
-; RUN: %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=wasm -mllvm -wasm-enable-eh %s | FileCheck %s
+; RUN: %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=wasm %s | FileCheck %s
 
 ; RUN: not %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=invalid %s 2>&1 | FileCheck -check-prefix=ERR %s
 ; RUN: not %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=dwarf %s 2>&1 | FileCheck -check-prefix=ERR-BE %s
diff --git a/clang/test/CodeGen/exception-model-flag.c b/clang/test/CodeGen/exception-model-flag.c
index f9713d88df592..797a9965ab5f4 100644
--- a/clang/test/CodeGen/exception-model-flag.c
+++ b/clang/test/CodeGen/exception-model-flag.c
@@ -13,6 +13,12 @@
 // SEH maps to the "wineh" spelling regardless of the requesting triple.
 // RUN: %clang_cc1 -triple i686-unknown-windows-gnu -fexceptions -exception-model=seh -emit-llvm %s -o - | FileCheck %s --check-prefix=WINEH
 
+// Wasm EH records the "wasm" model.
+// RUN: %clang_cc1 -triple wasm32-unknown-unknown -fexceptions -exception-model=wasm -emit-llvm %s -o - | FileCheck %s --check-prefix=WASM
+
+// Emscripten EH records the "emscripten" model.
+// RUN: %clang_cc1 -triple wasm32-unknown-emscripten -fexceptions -exception-model=emscripten -emit-llvm %s -o - | FileCheck %s --check-prefix=EMSCRIPTEN
+
 // A requested model that matches the target default is still recorded, so that
 // the flag's absence always means "unspecified".
 // RUN: %clang_cc1 -triple i686-unknown-linux-gnu -fexceptions -exception-model=dwarf -emit-llvm %s -o - | FileCheck %s --check-prefix=DWARF
@@ -30,6 +36,8 @@ void f(void) {}
 
 // SJLJ: !{i32 1, !"exception-model", !"sjlj"}
 // WINEH: !{i32 1, !"exception-model", !"wineh"}
+// WASM: !{i32 1, !"exception-model", !"wasm"}
+// EMSCRIPTEN: !{i32 1, !"exception-model", !"emscripten"}
 // DWARF: !{i32 1, !"exception-model", !"dwarf"}
 // NONE: !{i32 1, !"exception-model", !"none"}
 // UNSPEC-NOT: "exception-model"
diff --git a/clang/test/CodeGenCXX/builtins-eh-wasm.cpp b/clang/test/CodeGenCXX/builtins-eh-wasm.cpp
index b3a6ffc92e11b..dfb0116e19428 100644
--- a/clang/test/CodeGenCXX/builtins-eh-wasm.cpp
+++ b/clang/test/CodeGenCXX/builtins-eh-wasm.cpp
@@ -1,5 +1,5 @@
 // REQUIRES: webassembly-registered-target
-// RUN: %clang_cc1 -triple wasm32-unknown-unknown -fexceptions -fcxx-exceptions -target-feature +reference-types -target-feature +exception-handling -target-feature +multivalue -mllvm -wasm-enable-eh -exception-model=wasm -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple wasm32-unknown-unknown -fexceptions -fcxx-exceptions -target-feature +reference-types -target-feature +exception-handling -target-feature +multivalue -exception-model=wasm -emit-llvm -o - %s | FileCheck %s
 
 // Check if __builtin_wasm_throw and __builtin_wasm_rethrow are correctly
 // invoked when placed in try-catch.
diff --git a/clang/test/CodeGenCXX/wasm-eh.cpp b/clang/test/CodeGenCXX/wasm-eh.cpp
index 0b87107e476c7..a6dd939be733e 100644
--- a/clang/test/CodeGenCXX/wasm-eh.cpp
+++ b/clang/test/CodeGenCXX/wasm-eh.cpp
@@ -3,8 +3,8 @@
 // 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
+// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -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 -exception-model=wasm -target-feature +exception-handling -emit-llvm -o - -std=c++11 | FileCheck %s
 
 // Test code generation for Wasm EH using WebAssembly EH proposal.
 // (https://github.com/WebAssembly/exception-handling/blob/main/proposals/exception-handling/Exceptions.md)
@@ -421,9 +421,9 @@ int tls_wrapper_within_funclet() {
 // CHECK-NEXT:  call void @_ZSt9terminatev()
 
 
-// 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 2>&1 | FileCheck %s --check-prefix=WARNING-DEFAULT
-// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -mllvm -wasm-enable-eh -exception-model=wasm -target-feature +exception-handling -Wwasm-exception-spec -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=WARNING-ON
-// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -mllvm -wasm-enable-eh -exception-model=wasm -target-feature +exception-handling -Wno-wasm-exception-spec -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=WARNING-OFF
+// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -exception-model=wasm -target-feature +exception-handling -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=WARNING-DEFAULT
+// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -exception-model=wasm -target-feature +exception-handling -Wwasm-exception-spec -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=WARNING-ON
+// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -exception-model=wasm -target-feature +exception-handling -Wno-wasm-exception-spec -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=WARNING-OFF
 // RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fexceptions -fcxx-exceptions -emit-llvm -o - -std=c++11 2>&1 | FileCheck %s --check-prefix=EM-EH-WARNING
 
 // Wasm EH ignores dynamic exception specifications with types at the moment.
@@ -448,7 +448,7 @@ void exception_spec_throw_empty() throw() {
 // Here we only check if the command enables wasm exception handling in the
 // backend so that exception handling instructions can be generated in .s file.
 
-// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -mllvm -wasm-enable-eh -exception-model=wasm -target-feature +exception-handling -S -o - -std=c++11 | FileCheck %s --check-prefix=ASSEMBLY
+// RUN: %clang_cc1 %s -triple wasm32-unknown-unknown -fms-extensions -fexceptions -fcxx-exceptions -exception-model=wasm -target-feature +exception-handling -S -o - -std=c++11 | FileCheck %s --check-prefix=ASSEMBLY
 
 // ASSEMBLY: try
 // ASSEMBLY: catch
diff --git a/clang/test/CodeGenObjC/wasm32-eh-arc.m b/clang/test/CodeGenObjC/wasm32-eh-arc.m
index 3d78d633953c6..021084906eccb 100644
--- a/clang/test/CodeGenObjC/wasm32-eh-arc.m
+++ b/clang/test/CodeGenObjC/wasm32-eh-arc.m
@@ -1,5 +1,5 @@
 // REQUIRES: webassembly-registered-target
-// RUN: %clang_cc1 -triple wasm32-unknown-emscripten -fobjc-runtime=gnustep-2.2 -fobjc-arc -fexceptions -fobjc-exceptions -exception-model=wasm -mllvm -wasm-enable-eh -emit-llvm -o - %s | FileCheck --enable-var-scope %s
+// RUN: %clang_cc1 -triple wasm32-unknown-emscripten -fobjc-runtime=gnustep-2.2 -fobjc-arc -fexceptions -fobjc-exceptions -exception-model=wasm -emit-llvm -o - %s | FileCheck --enable-var-scope %s
 __attribute__((objc_root_class)) @interface Object @end
 extern void mayThrowObjC();
 
diff --git a/clang/test/CodeGenObjC/wasm32-eh.m b/clang/test/CodeGenObjC/wasm32-eh.m
index 09062bdea1894..d25f17319b76e 100644
--- a/clang/test/CodeGenObjC/wasm32-eh.m
+++ b/clang/test/CodeGenObjC/wasm32-eh.m
@@ -1,5 +1,5 @@
 // REQUIRES: webassembly-registered-target
-// RUN: %clang_cc1 -triple wasm32-unknown-emscripten -fobjc-exceptions -fexceptions -exception-model=wasm -mllvm -wasm-enable-eh -emit-llvm -fobjc-runtime=gnustep-2.2 -o - %s | FileCheck --enable-var-scope %s
+// RUN: %clang_cc1 -triple wasm32-unknown-emscripten -fobjc-exceptions -fexceptions -exception-model=wasm -emit-llvm -fobjc-runtime=gnustep-2.2 -o - %s | FileCheck --enable-var-scope %s
 
 __attribute__((objc_root_class)) @interface Object
 @end
diff --git a/clang/test/CodeGenObjCXX/wasm32-eh-objcxx.mm b/clang/test/CodeGenObjCXX/wasm32-eh-objcxx.mm
index 3af09f7055b98..cfc87f4fe5b54 100644
--- a/clang/test/CodeGenObjCXX/wasm32-eh-objcxx.mm
+++ b/clang/test/CodeGenObjCXX/wasm32-eh-objcxx.mm
@@ -1,5 +1,5 @@
 // REQUIRES: webassembly-registered-target
-// RUN: %clang_cc1 -target-feature +exception-handling -triple wasm32-unknown-emscripten -fobjc-runtime=gnustep-2.2 -fexceptions -fobjc-exceptions -fcxx-exceptions -exception-model=wasm -mllvm -wasm-enable-eh -emit-llvm -o - %s | FileCheck --enable-var-scope %s
+// RUN: %clang_cc1 -target-feature +exception-handling -triple wasm32-unknown-emscripten -fobjc-runtime=gnustep-2.2 -fexceptions -fobjc-exceptions -fcxx-exceptions -exception-model=wasm -emit-llvm -o - %s | FileCheck --enable-var-scope %s
 
 struct ThrowingDestructor {
   ~ThrowingDestructor() noexcept(false);
diff --git a/clang/test/Driver/wasm-toolchain.c b/clang/test/Driver/wasm-toolchain.c
index 7a36440494f42..e5fadaba174da 100644
--- a/clang/test/Driver/wasm-toolchain.c
+++ b/clang/test/Driver/wasm-toolchain.c
@@ -155,11 +155,11 @@
 // WASM_EXCEPTIONS_FEMSCRIPTEN_EH: invalid argument '-fwasm-exceptions' not allowed with '-femscripten-exceptions'
 
 // '-fwasm-exceptions' sets +exception-handling, -multivalue, -reference-types,
-// "-exception-model=wasm", and '-mllvm -wasm-enable-eh'
+// and "-exception-model=wasm"
 // RUN: %clang -### --target=wasm32-unknown-unknown \
 // RUN:    --sysroot=/foo %s -fwasm-exceptions 2>&1 \
 // RUN:  | FileCheck -check-prefix=WASM_EXCEPTIONS %s
-// WASM_EXCEPTIONS: "-cc1" {{.*}} "-target-feature" "+exception-handling" "-target-feature" "+multivalue" "-target-feature" "+reference-types" "-exception-model=wasm" "-mllvm" "-wasm-enable-eh"
+// WASM_EXCEPTIONS: "-cc1" {{.*}} "-target-feature" "+exception-handling" "-target-feature" "+multivalue" "-target-feature" "+reference-types" "-exception-model=wasm"
 
 // '-fwasm-exceptions' not allowed with '-mllvm -enable-emscripten-sjlj'
 // RUN: not %clang -### --target=wasm32-unknown-unknown \
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyCodeGenPassBuilder.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyCodeGenPassBuilder.cpp
index c53072764bc82..960f01f1e73a0 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyCodeGenPassBuilder.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyCodeGenPassBuilder.cpp
@@ -41,13 +41,11 @@ using namespace llvm;
 
 namespace WebAssembly {
 extern cl::opt<bool> WasmDisableExplicitLocals;
-extern cl::opt<bool> WasmEnableEH;
 extern cl::opt<bool> WasmEnableEmSjLj;
 extern cl::opt<bool> WasmEnableSjLj;
 } // namespace WebAssembly
 
 using llvm::WebAssembly::WasmDisableExplicitLocals;
-using llvm::WebAssembly::WasmEnableEH;
 using llvm::WebAssembly::WasmEnableEmSjLj;
 using llvm::WebAssembly::WasmEnableSjLj;
 
@@ -126,7 +124,8 @@ void WebAssemblyCodeGenPassBuilder::addIRPasses(PassManagerWrapper &PMW) {
   // passes and Emscripten SjLj handling expects all invokes to be lowered
   // before.
   bool EnableEmEH = TM.Options.ExceptionModel == ExceptionHandling::Emscripten;
-  if (!EnableEmEH && !WasmEnableEH) {
+  bool EnableWasmEH = TM.Options.ExceptionModel == ExceptionHandling::Wasm;
+  if (!EnableEmEH && !EnableWasmEH) {
     addFunctionPass(LowerInvokePass(), PMW);
     // The lower invoke pass may create unreachable code. Remove it in order not
     // to process dead blocks in setjmp/longjmp handling.
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
index 3b054f80027c5..6c15b2e3b5864 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -57,10 +57,6 @@ cl::opt<bool> WebAssembly::WasmEnableEmSjLj(
     "enable-emscripten-sjlj",
     cl::desc("WebAssembly Emscripten-style setjmp/longjmp handling"),
     cl::init(false));
-// Exception handling using wasm EH instructions
-cl::opt<bool>
-    WebAssembly::WasmEnableEH("wasm-enable-eh",
-                              cl::desc("WebAssembly exception handling"));
 // setjmp/longjmp handling using wasm EH instructions
 cl::opt<bool> WebAssembly::WasmEnableSjLj(
     "wasm-enable-sjlj", cl::desc("WebAssembly setjmp/longjmp handling"));
@@ -129,7 +125,6 @@ static Reloc::Model getEffectiveRelocModel(std::optional<Reloc::Model> RM) {
 }
 
 using WebAssembly::WasmDisableExplicitLocals;
-using WebAssembly::WasmEnableEH;
 using WebAssembly::WasmEnableEmSjLj;
 using WebAssembly::WasmEnableSjLj;
 
@@ -137,10 +132,6 @@ static void basicCheckForEHAndSjLj(TargetMachine *TM) {
 
   bool EnableEmEH = TM->Options.ExceptionModel == ExceptionHandling::Emscripten;
 
-  // You can't enable two modes of EH at the same time
-  if (EnableEmEH && WasmEnableEH)
-    report_fatal_error(
-        "-exception-model=emscripten not allowed with -wasm-enable-eh");
   // You can't enable two modes of SjLj at the same time
   if (WasmEnableEmSjLj && WasmEnableSjLj)
     report_fatal_error(
@@ -151,9 +142,9 @@ static void basicCheckForEHAndSjLj(TargetMachine *TM) {
         "-exception-model=emscripten not allowed with -wasm-enable-sjlj");
 
   if (TM->Options.ExceptionModel == ExceptionHandling::Default) {
-    // FIXME: These flags should be removed in favor of directly using the
-    // generically configured ExceptionsType
-    if (WebAssembly::WasmEnableEH || WebAssembly::WasmEnableSjLj)
+    // FIXME: This flag should be removed in favor of directly using the
+    // generically configured ExceptionsType.
+    if (WebAssembly::WasmEnableSjLj)
       TM->Options.ExceptionModel = ExceptionHandling::Wasm;
   }
 
@@ -164,17 +155,9 @@ static void basicCheckForEHAndSjLj(TargetMachine *TM) {
       TM->Options.ExceptionModel != ExceptionHandling::Emscripten)
     report_fatal_error(
         "-exception-model should be either 'none', 'wasm', or 'emscripten'");
-  if (WasmEnableEH && TM->Options.ExceptionModel != ExceptionHandling::Wasm)
-    report_fatal_error(
-        "-wasm-enable-eh only allowed with -exception-model=wasm");
   if (WasmEnableSjLj && TM->Options.ExceptionModel != ExceptionHandling::Wasm)
     report_fatal_error(
         "-wasm-enable-sjlj only allowed with -exception-model=wasm");
-  if ((!WasmEnableEH && !WasmEnableSjLj) &&
-      TM->Options.ExceptionModel == ExceptionHandling::Wasm)
-    report_fatal_error(
-        "-exception-model=wasm only allowed with at least one of "
-        "-wasm-enable-eh or -wasm-enable-sjlj");
 
   // Currently it is allowed to mix Wasm EH with Emscripten SjLj as an interim
   // measure, but some code will error out at compile time in this combination.
@@ -334,7 +317,8 @@ void WebAssemblyPassConfig::addIRPasses() {
   // passes and Emscripten SjLj handling expects all invokes to be lowered
   // before.
   bool EnableEmEH = TM->Options.ExceptionModel == ExceptionHandling::Emscripten;
-  if (!EnableEmEH && !WasmEnableEH) {
+  bool EnableWasmEH = TM->Options.ExceptionModel == ExceptionHandling::Wasm;
+  if (!EnableEmEH && !EnableWasmEH) {
     addPass(createLowerInvokePass());
     // The lower invoke pass may create unreachable code. Remove it in order not
     // to process dead blocks in setjmp/longjmp handling.
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.h b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.h
index cff4d345b8516..a7ff3f4afa9b7 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.h
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.h
@@ -25,7 +25,6 @@ namespace WebAssembly {
 // Exception handling / setjmp-longjmp handling command-line options
 extern cl::opt<bool> WasmDisableExplicitLocals;
 extern cl::opt<bool> WasmEnableEmSjLj; // asm.js-style SjLJ
-extern cl::opt<bool> WasmEnableEH;     // EH using Wasm EH instructions
 extern cl::opt<bool> WasmEnableSjLj;   // SjLj using Wasm EH instructions
 extern cl::opt<bool> WasmUseLegacyEH;  // Legacy Wasm EH
 } // namespace WebAssembly
diff --git a/llvm/test/CodeGen/WebAssembly/cfg-stackify-eh-legacy.ll b/llvm/test/CodeGen/WebAssembly/cfg-stackify-eh-legacy.ll
index b3bf255b2391e..7b7827a71d47d 100644
--- a/llvm/test/CodeGen/WebAssembly/cfg-stackify-eh-legacy.ll
+++ b/llvm/test/CodeGen/WebAssembly/cfg-stackify-eh-legacy.ll
@@ -1,9 +1,9 @@
 ; REQUIRES: asserts
-; RUN: llc < %s -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -disable-block-placement -verify-machineinstrs -fast-isel=false -machine-sink-split-probability-threshold=0 -cgp-freq-ratio-to-skip-merge=1000 -wasm-enable-eh -wasm-use-legacy-eh -exception-model=wasm -mattr=+exception-handling,bulk-memory | FileCheck %s
-; RUN: llc < %s -disable-wasm-fallthrough-return-opt -disable-block-placement -verify-machineinstrs -fast-isel=false -machine-sink-split-probability-threshold=0 -cgp-freq-ratio-to-skip-merge=1000 -wasm-enable-eh -wasm-use-legacy-eh -exception-model=wasm -mattr=+exception-handling,bulk-memory
-; RUN: llc < %s -O0 -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -verify-machineinstrs -wasm-enable-eh -wasm-use-legacy-eh -exception-model=wasm -mattr=+exception-handling,-bulk-memory,-bulk-memory-opt | FileCheck %s --check-prefix=NOOPT
-; RUN: llc < %s -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -disa...
[truncated]

aheejin

Thanks! This has to wait until emscripten-core/emscripten#27739 lands to pass our autorollers.

Previously in LLVM, we had `-mllvm -enable-emscripten-cxx-exceptions` to enable Emscriten EH, and `-mllvm -wasm-enable-eh` to enable Wasm EH. These were separate Wasm backend flags. Also there is a separate `-exception-model=` LLVM flag used for all LLVM targets. We used `wasm` for Wasm EH and `none` for Emscripten EH. This was a common LLVM flag which we didn't directly use but fed LLVM because it was a common flag. Recently a series of Clang+LLVM EH flag refactoring was done, and now LLVM is using `-exception-model` to control all EH modes. So Emscripten EH will be enabled by `-exception-model=emscripten`, and Wasm EH by `-exception-model=wasm`, and we don't need the Wasm-specific LLVM flags. `-enable-emscripten-cxx-exceptions` was removed in #27704. This removes `-wasm-enable-eh`. This has to land before llvm/llvm-project#224313. This also temporarily disable EH LTO tests, which we will reenable after llvm/llvm-project#224313 lands.

arsenm requested review from aheejin, dschuff and sbc100 September 17, 2026 13:59

arsenm added the backend:WebAssembly label Sep 17, 2026 — with Graphite App

arsenm marked this pull request as ready for review September 17, 2026 13:59

llvmorg-github-actions Bot added the clang:driver 'clang' and 'clang++' user-facing binaries. Not 'clang-cl' label Sep 17, 2026

aheejin mentioned this pull request Sep 17, 2026

[EH] Remove -wasm-enable-eh LLVM flag emscripten-core/emscripten#27739

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aheejin approved these changes Sep 17, 2026

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WebAssembly: Remove -wasm-enable-eh cl::opt in favor of -exception-model=wasm - #224313

WebAssembly: Remove -wasm-enable-eh cl::opt in favor of -exception-model=wasm#224313
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