add unconditional warning before handling StackOverflow

src/codegen.cpp

@@ -1487,7 +1487,8 @@ static const auto except_enter_func = new JuliaFunction<>{
     "julia.except_enter",
     [](LLVMContext &C) {
          auto T_pjlvalue = JuliaType::get_pjlvalue_ty(C);
-         return FunctionType::get(getInt32Ty(C), {T_pjlvalue}, false); },
+         auto RT = StructType::get(getInt32Ty(C), getInt8PtrTy(C));
+         return FunctionType::get(RT, {T_pjlvalue}, false); },
     [](LLVMContext &C) { return AttributeList::get(C,
             Attributes(C, {Attribute::ReturnsTwice}),
             AttributeSet(),
@@ -9377,10 +9378,12 @@ static jl_llvm_functions_t
                 ctx.SAvalues[cursor] = jl_cgval_t(excstack_state, (jl_value_t*)jl_ulong_type, NULL);
                 ctx.ssavalue_assigned[cursor] = true;
                 // Actually enter the exception frame
-                CallInst *sj = ctx.builder.CreateCall(prepare_call(except_enter_func), {get_current_task(ctx)});
+                auto ct = get_current_task(ctx);
+                CallInst *sj = ctx.builder.CreateCall(prepare_call(except_enter_func), {ct});
                 // We need to mark this on the call site as well. See issue #6757
                 sj->setCanReturnTwice();
-                Value *isz = ctx.builder.CreateICmpEQ(sj, ConstantInt::get(getInt32Ty(ctx.builder.getContext()), 0));
+                Value *isz = ctx.builder.CreateICmpEQ(ctx.builder.CreateExtractValue(sj, 0), ConstantInt::get(getInt32Ty(ctx.builder.getContext()), 0));
+                Value *ehbuf = ctx.builder.CreateExtractValue(sj, 1);
                 BasicBlock *tryblk = BasicBlock::Create(ctx.builder.getContext(), "try", f);
                 BasicBlock *catchpop = BasicBlock::Create(ctx.builder.getContext(), "catch_pop", f);
                 BasicBlock *handlr = NULL;
@@ -9398,6 +9401,12 @@ static jl_llvm_functions_t
                     ctx.builder.CreateBr(handlr);
                 }
                 ctx.builder.SetInsertPoint(tryblk);
+                auto ehptr = ctx.builder.CreateInBoundsGEP(
+                    ctx.types().T_ptr,
+                    emit_bitcast(ctx, ct, ctx.types().T_ppint8),
+                    ConstantInt::get(ctx.types().T_size, offsetof(jl_task_t, eh) / ctx.types().sizeof_ptr),
+                    "eh");
+                ctx.builder.CreateAlignedStore(ehbuf, ehptr, ctx.types().alignof_ptr);
             }
         }
         else {

src/interpreter.c

@@ -529,6 +529,7 @@ static jl_value_t *eval_body(jl_array_t *stmts, interpreter_state *s, size_t ip,
                 jl_value_t *new_scope = eval_value(jl_enternode_scope(stmt), s);
                 ct->scope = new_scope;
                 if (!jl_setjmp(__eh.eh_ctx, 1)) {
+                    ct->eh = &__eh;
                     eval_body(stmts, s, next_ip, toplevel);
                     jl_unreachable();
                 }
@@ -537,6 +538,7 @@ static jl_value_t *eval_body(jl_array_t *stmts, interpreter_state *s, size_t ip,
             }
             else {
                 if (!jl_setjmp(__eh.eh_ctx, 1)) {
+                    ct->eh = &__eh;
                     eval_body(stmts, s, next_ip, toplevel);
                     jl_unreachable();
                 }

src/julia.h

@@ -2374,6 +2374,7 @@ extern int had_exception;
     __eh_ct = jl_current_task;                                      \
     size_t __excstack_state = jl_excstack_state(__eh_ct);           \
     jl_enter_handler(__eh_ct, &__eh);                               \
+    __eh_ct->eh = &__eh;                                            \
     if (1)
     /* TRY BLOCK; */
 #define JL_CATCH                                                    \
@@ -2390,7 +2391,7 @@ extern int had_exception;
     size_t __excstack_state = jl_excstack_state(__eh_ct);           \
     jl_enter_handler(__eh_ct, &__eh);                               \
     if (!jl_setjmp(__eh.eh_ctx, 0))                                 \
-        for (i__try=1; i__try; i__try=0, /* TRY BLOCK; */  jl_eh_restore_state_noexcept(__eh_ct, &__eh))
+        for (i__try=1, __eh_ct->eh = &__eh; i__try; i__try=0, /* TRY BLOCK; */ jl_eh_restore_state_noexcept(__eh_ct, &__eh))
 
 #define JL_CATCH                                                    \
     else                                                            \

src/llvm-lower-handlers.cpp

@@ -41,13 +41,14 @@ using namespace llvm;
 /* Lowers Julia Exception Handlers and colors EH frames.
  *
  *  Our task is to lower:
- * call void @julia.except_enter(ct)
+ * call {i32, ptr} @julia.except_enter(ct)
  * <...>
  * call void jl_pop_handler(1)
  *
  * to
  *
  * call void @jl_enter_handler(ct, jl_handler *%buff)
+ * call i32 @jl_setjmp(jmpbuf[] %buff, 0)
  * <...>
  * call void jl_pop_handler(1)
  *
@@ -209,7 +210,25 @@ static bool lowerExcHandlers(Function &F) {
             new_enter->setMetadata(LLVMContext::MD_dbg, dbg);
             sj->setMetadata(LLVMContext::MD_dbg, dbg);
         }
-        enter->replaceAllUsesWith(sj);
+        SmallVector<Instruction*> ToErase;
+        for (auto *U : enter->users()) {
+            if (auto *EEI = dyn_cast<ExtractValueInst>(U)) {
+                if (EEI->getNumIndices() == 1) {
+                    if (EEI->getIndices()[0] == 0)
+                        EEI->replaceAllUsesWith(sj);
+                    else
+                        EEI->replaceAllUsesWith(buff);
+                    ToErase.push_back(EEI);
+                }
+            }
+        }
+        for (auto *EEI : ToErase)
+            EEI->eraseFromParent();
+        if (!enter->use_empty()) {
+            Value *agg = InsertValueInst::Create(UndefValue::get(enter->getType()), sj, ArrayRef<unsigned>(0), "", enter);
+            agg = InsertValueInst::Create(agg, buff, ArrayRef<unsigned>(1), "", enter);
+            enter->replaceAllUsesWith(agg);
+        }
         enter->eraseFromParent();
     }
     // Insert lifetime end intrinsics after every leave.

src/rtutils.c

@@ -248,7 +248,6 @@ JL_DLLEXPORT void jl_enter_handler(jl_task_t *ct, jl_handler_t *eh)
     eh->locks_len = ct->ptls->locks.len;
     eh->defer_signal = ct->ptls->defer_signal;
     eh->world_age = ct->world_age;
-    ct->eh = eh;
 #ifdef ENABLE_TIMINGS
     eh->timing_stack = ct->ptls->timing_stack;
 #endif

src/signal-handling.c

@@ -309,6 +309,11 @@ static void jl_check_profile_autostop(void)
     }
 }
 
+static void stack_overflow_warning(void)
+{
+    jl_safe_printf("Warning: detected a stack overflow; program state may be corrupted, so further execution might be unreliable.\n");
+}
+
 #if defined(_WIN32)
 #include "signals-win.c"
 #else

src/signals-mach.c

@@ -353,7 +353,7 @@ kern_return_t catch_mach_exception_raise(
     // XXX: jl_throw_in_thread or segv_handler will eventually check this, but
     //      we would like to avoid some of this work if we could detect this earlier
     // if (jl_has_safe_restore(ptls2)) {
-    //     jl_throw_in_thread(ptls2, thread, jl_stackovf_exception);
+    //     jl_throw_in_thread(ptls2, thread, NULL);
     //     return KERN_SUCCESS;
     // }
     if (jl_atomic_load_acquire(&ptls2->gc_state) == JL_GC_STATE_WAITING)
@@ -385,6 +385,7 @@ kern_return_t catch_mach_exception_raise(
         return KERN_FAILURE;
     jl_value_t *excpt;
     if (is_addr_on_stack(jl_atomic_load_relaxed(&ptls2->current_task), (void*)fault_addr)) {
+        stack_overflow_warning();
         excpt = jl_stackovf_exception;
     }
     else if (is_write_fault(exc_state)) // false for alignment errors

src/signals-unix.c

@@ -404,6 +404,7 @@ JL_NO_ASAN static void segv_handler(int sig, siginfo_t *info, void *context)
     if (ct->eh == NULL)
         sigdie_handler(sig, info, context);
     if ((sig != SIGBUS || info->si_code == BUS_ADRERR) && is_addr_on_stack(ct, info->si_addr)) { // stack overflow and not a BUS_ADRALN (alignment error)
+        stack_overflow_warning();
         jl_throw_in_ctx(ct, jl_stackovf_exception, sig, context);
     }
     else if (jl_is_on_sigstack(ct->ptls, info->si_addr, context)) {

src/signals-win.c

@@ -244,6 +244,7 @@ LONG WINAPI jl_exception_handler(struct _EXCEPTION_POINTERS *ExceptionInfo)
         case EXCEPTION_STACK_OVERFLOW:
             if (ct->eh != NULL) {
                 ptls->needs_resetstkoflw = 1;
+                stack_overflow_warning();
                 jl_throw_in_ctx(ct, jl_stackovf_exception, ExceptionInfo->ContextRecord);
                 return EXCEPTION_CONTINUE_EXECUTION;
             }

test/llvmpasses/lower-handlers-addrspaces.ll

@@ -6,7 +6,7 @@ target triple = "amdgcn-amd-amdhsa"
 target datalayout = "e-p:64:64-p1:64:64-p2:32:32-p3:32:32-p4:64:64-p5:32:32-p6:32:32-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64-S32-A5-G1-ni:7-ni:10:11:12:13"
 
 attributes #1 = { returns_twice }
-declare i32 @julia.except_enter({}*) #1
+declare {i32, i8*} @julia.except_enter({}*) #1
 declare void @ijl_pop_handler({}*, i32)
 declare i8**** @julia.ptls_states()
 declare i8**** @julia.get_pgcstack()
@@ -17,7 +17,8 @@ top:
 ; CHECK: call void @llvm.lifetime.start
 ; CHECK: call void @ijl_enter_handler
 ; CHECK: setjmp
-    %r = call i32 @julia.except_enter({}* null)
+    %rb = call {i32, i8*} @julia.except_enter({}* null)
+    %r = extractvalue {i32, i8*} %rb, 0
     %cmp = icmp eq i32 %r, 0
     br i1 %cmp, label %try, label %catch
 try:

test/llvmpasses/lower-handlers.ll

@@ -3,7 +3,7 @@
 ; RUN: opt --load-pass-plugin=libjulia-codegen%shlibext -passes='function(LowerExcHandlers)' -S %s | FileCheck %s
 
 attributes #1 = { returns_twice }
-declare i32 @julia.except_enter({}*) #1
+declare {i32, i8*} @julia.except_enter({}*) #1
 declare void @ijl_pop_handler({}*, i32)
 declare i8**** @julia.ptls_states()
 declare i8**** @julia.get_pgcstack()
@@ -14,10 +14,13 @@ top:
 ; CHECK: call void @llvm.lifetime.start
 ; CHECK: call void @ijl_enter_handler
 ; CHECK: setjmp
-    %r = call i32 @julia.except_enter({}* null)
+    %rb = call {i32, i8*} @julia.except_enter({}* null)
+    %r = extractvalue {i32, i8*} %rb, 0
+    %b = extractvalue {i32, i8*} %rb, 1
     %cmp = icmp eq i32 %r, 0
     br i1 %cmp, label %try, label %catch
 try:
+    %lcssa = phi {i32, i8*} [ %rb, %top ]
     br label %after
 catch:
     br label %after