[WebAssembly] Use rethrow intrinsic in the rethrow block

Summary:
Because in wasm we merge all catch clauses into one big catchpad, in
case none of the types in catch handlers matches after we test against
each of them, we should unwind to the next EH enclosing scope. For this,
we should NOT use a call to `__cxa_rethrow` but rather a call to our own
rethrow intrinsic, because what we're trying to do here is just to
transfer the control flow into the next enclosing EH pad (or the
caller). Calls to `__cxa_rethrow` should only be used after a call to
`__cxa_begin_catch`.

Reviewers: dschuff

Subscribers: sbc100, jgravelle-google, sunfish, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D59353

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@356317 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Basic/BuiltinsWebAssembly.def b/include/clang/Basic/BuiltinsWebAssembly.def
index 0241436b5b871a1b4dd829aa679fd8d08cecbda5..e109ee620bbbf1212061ebd6876d5227b35cb2d2 100644 (file)
--- a/include/clang/Basic/BuiltinsWebAssembly.def
+++ b/include/clang/Basic/BuiltinsWebAssembly.def
@@ -37,7 +37,7 @@ BUILTIN(__builtin_wasm_max_f64, "ddd", "nc")
 
 // Exception handling builtins.
 TARGET_BUILTIN(__builtin_wasm_throw, "vUiv*", "r", "exception-handling")
-TARGET_BUILTIN(__builtin_wasm_rethrow, "v", "r", "exception-handling")
+TARGET_BUILTIN(__builtin_wasm_rethrow_in_catch, "v", "r", "exception-handling")
 
 // Atomic wait and notify.
 BUILTIN(__builtin_wasm_atomic_wait_i32, "ii*iLLi", "n")

diff --git a/lib/CodeGen/CGBuiltin.cpp b/lib/CodeGen/CGBuiltin.cpp
index 96289720abe7c4b1eaed6a59154af34548f06459..4d9c76ae7fc4b91cc392536cc063e07dac8bdc36 100644 (file)
--- a/lib/CodeGen/CGBuiltin.cpp
+++ b/lib/CodeGen/CGBuiltin.cpp
@@ -13513,8 +13513,8 @@ Value *CodeGenFunction::EmitWebAssemblyBuiltinExpr(unsigned BuiltinID,
     Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_throw);
     return Builder.CreateCall(Callee, {Tag, Obj});
   }
-  case WebAssembly::BI__builtin_wasm_rethrow: {
-    Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_rethrow);
+  case WebAssembly::BI__builtin_wasm_rethrow_in_catch: {
+    Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_rethrow_in_catch);
     return Builder.CreateCall(Callee);
   }
   case WebAssembly::BI__builtin_wasm_atomic_wait_i32: {

diff --git a/lib/CodeGen/CGException.cpp b/lib/CodeGen/CGException.cpp
index 8335c9f6878eeceb102268c6b8f3f467d48258b9..748029b860960dfde98f4d2777872926e61ed86f 100644 (file)
--- a/lib/CodeGen/CGException.cpp
+++ b/lib/CodeGen/CGException.cpp
@@ -1259,7 +1259,9 @@ void CodeGenFunction::ExitCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock) {
     }
     assert(RethrowBlock != WasmCatchStartBlock && RethrowBlock->empty());
     Builder.SetInsertPoint(RethrowBlock);
-    CGM.getCXXABI().emitRethrow(*this, /*isNoReturn=*/true);
+    llvm::Function *RethrowInCatchFn =
+        CGM.getIntrinsic(llvm::Intrinsic::wasm_rethrow_in_catch);
+    EmitNoreturnRuntimeCallOrInvoke(RethrowInCatchFn, {});
   }
 
   EmitBlock(ContBB);

diff --git a/test/CodeGen/builtins-wasm.c b/test/CodeGen/builtins-wasm.c
index bba615d3a2d494ec6af6d3c1dbfb5fd962fce77a..3c5db7268d293a08fd88564223014f93f77f3f4a 100644 (file)
--- a/test/CodeGen/builtins-wasm.c
+++ b/test/CodeGen/builtins-wasm.c
@@ -44,10 +44,10 @@ void throw(unsigned int tag, void *obj) {
   // WEBASSEMBLY64: call void @llvm.wasm.throw(i32 %{{.*}}, i8* %{{.*}})
 }
 
-void rethrow(void) {
-  return __builtin_wasm_rethrow();
-  // WEBASSEMBLY32: call void @llvm.wasm.rethrow()
-  // WEBASSEMBLY64: call void @llvm.wasm.rethrow()
+void rethrow_in_catch(void) {
+  return __builtin_wasm_rethrow_in_catch();
+  // WEBASSEMBLY32: call void @llvm.wasm.rethrow.in.catch()
+  // WEBASSEMBLY64: call void @llvm.wasm.rethrow.in.catch()
 }
 
 int atomic_wait_i32(int *addr, int expected, long long timeout) {

diff --git a/test/CodeGenCXX/wasm-eh.cpp b/test/CodeGenCXX/wasm-eh.cpp
index ea77fec82039232ea2aa18e0b504295b8783cdeb..fbbf4dd3fda809528eac65a584f129eadea85f25 100644 (file)
--- a/test/CodeGenCXX/wasm-eh.cpp
+++ b/test/CodeGenCXX/wasm-eh.cpp
@@ -62,7 +62,7 @@ void test0() {
 // CHECK-NEXT:   br label %[[TRY_CONT_BB]]
 
 // CHECK: [[RETHROW_BB]]:
-// CHECK-NEXT:   call void @__cxa_rethrow() {{.*}} [ "funclet"(token %[[CATCHPAD]]) ]
+// CHECK-NEXT:   call void @llvm.wasm.rethrow.in.catch() {{.*}} [ "funclet"(token %[[CATCHPAD]]) ]
 // CHECK-NEXT:   unreachable
 
 // Single catch-all
@@ -232,7 +232,7 @@ void test6() {
 // CHECK:   catchret from %[[CATCHPAD]] to label %{{.*}}
 
 // CHECK: [[RETHROW_BB]]:
-// CHECK-NEXT:   invoke void @__cxa_rethrow() {{.*}} [ "funclet"(token %[[CATCHPAD]]) ]
+// CHECK-NEXT:   invoke void @llvm.wasm.rethrow.in.catch() {{.*}} [ "funclet"(token %[[CATCHPAD]]) ]
 // CHECK-NEXT:          to label %[[UNREACHABLE_BB:.*]] unwind label %[[EHCLEANUP_BB1:.*]]
 
 // CHECK: [[EHCLEANUP_BB2]]:
@@ -296,7 +296,7 @@ void test7() {
 
 // CHECK:   catchret from %[[CATCHPAD0]] to label
 
-// CHECK:   invoke void @__cxa_rethrow() {{.*}} [ "funclet"(token %[[CATCHPAD0]]) ]
+// CHECK:   invoke void @llvm.wasm.rethrow.in.catch() {{.*}} [ "funclet"(token %[[CATCHPAD0]]) ]
 
 // CHECK:   %[[CLEANUPPAD1:.*]] = cleanuppad within %[[CATCHPAD0]] []
 // CHECK:   cleanupret from %[[CLEANUPPAD1]] unwind label
@@ -368,11 +368,11 @@ void test8() {
 
 // CHECK:   catchret from %[[CATCHPAD1]] to label
 
-// CHECK:   invoke void @__cxa_rethrow() {{.*}} [ "funclet"(token %[[CATCHPAD1]]) ]
+// CHECK:   invoke void @llvm.wasm.rethrow.in.catch() {{.*}} [ "funclet"(token %[[CATCHPAD1]]) ]
 
 // CHECK:   catchret from %[[CATCHPAD0]] to label
 
-// CHECK:   call void @__cxa_rethrow() {{.*}} [ "funclet"(token %[[CATCHPAD0]]) ]
+// CHECK:   call void @llvm.wasm.rethrow.in.catch() {{.*}} [ "funclet"(token %[[CATCHPAD0]]) ]
 // CHECK:   unreachable
 
 // CHECK:   %[[CLEANUPPAD0:.*]] = cleanuppad within %[[CATCHPAD1]] []