Use safepoint to deliver SIGINT

base/c.jl

@@ -202,8 +202,20 @@ end
 # within a long-running C routine.
 sigatomic_begin() = ccall(:jl_sigatomic_begin, Void, ())
 sigatomic_end() = ccall(:jl_sigatomic_end, Void, ())
-disable_sigint(f::Function) = try sigatomic_begin(); f(); finally sigatomic_end(); end
-reenable_sigint(f::Function) = try sigatomic_end(); f(); finally sigatomic_begin(); end
+function disable_sigint(f::Function)
+    sigatomic_begin()
+    res = f()
+    # Exception unwind sigatomic automatically
+    sigatomic_end()
+    res
+end
+function reenable_sigint(f::Function)
+    sigatomic_end()
+    res = f()
+    # Exception unwind sigatomic automatically
+    sigatomic_begin()
+    res
+end
 
 function ccallable(f::Function, rt::Type, argt::Type, name::Union{AbstractString,Symbol}=string(f))
     ccall(:jl_extern_c, Void, (Any, Any, Any, Cstring), f, rt, argt, name)

base/inference.jl

@@ -1562,6 +1562,7 @@ function typeinf_loop(frame)
         frame.inworkq || typeinf_frame(frame)
         return
     end
+    ccall(:jl_sigatomic_begin, Void, ())
     try
         in_typeinf_loop = true
         # the core type-inference algorithm
@@ -1608,6 +1609,7 @@ function typeinf_loop(frame)
         println(ex)
         ccall(:jlbacktrace, Void, ())
     end
+    ccall(:jl_sigatomic_end, Void, ())
     nothing
 end
 

src/Makefile

@@ -28,7 +28,7 @@ SRCS := \
 	jltypes gf typemap ast builtins module interpreter \
 	alloc dlload sys init task array dump toplevel jl_uv jlapi signal-handling \
 	simplevector APInt-C runtime_intrinsics runtime_ccall \
-	threadgroup threading stackwalk gc
+	threadgroup threading stackwalk gc safepoint
 
 ifeq ($(JULIACODEGEN),LLVM)
 SRCS += codegen disasm debuginfo llvm-simdloop llvm-gcroot

src/ast.c

@@ -230,6 +230,7 @@ static jl_ast_context_list_t *jl_ast_ctx_freed = NULL;
 
 static jl_ast_context_t *jl_ast_ctx_enter(void)
 {
+    JL_SIGATOMIC_BEGIN();
     JL_LOCK_NOGC(&flisp_lock);
     jl_ast_context_list_t *node;
     jl_ast_context_t *ctx;
@@ -267,6 +268,7 @@ static jl_ast_context_t *jl_ast_ctx_enter(void)
 
 static void jl_ast_ctx_leave(jl_ast_context_t *ctx)
 {
+    JL_SIGATOMIC_END();
     if (--ctx->ref)
         return;
     JL_LOCK_NOGC(&flisp_lock);
@@ -285,6 +287,8 @@ void jl_init_frontend(void)
     jl_ast_main_ctx.task = jl_current_task;
     jl_ast_context_list_insert(&jl_ast_ctx_using, &jl_ast_main_ctx.list);
     jl_init_ast_ctx(&jl_ast_main_ctx);
+    // To match the one in jl_ast_ctx_leave
+    JL_SIGATOMIC_BEGIN();
     jl_ast_ctx_leave(&jl_ast_main_ctx);
 }
 
@@ -758,6 +762,7 @@ jl_value_t *jl_parse_eval_all(const char *fname, size_t len,
             form = scm_to_julia(fl_ctx, expansion, 0);
             jl_sym_t *head = NULL;
             if (jl_is_expr(form)) head = ((jl_expr_t*)form)->head;
+            JL_SIGATOMIC_END();
             if (head == jl_incomplete_sym)
                 jl_errorf("syntax: %s", jl_string_data(jl_exprarg(form,0)));
             else if (head == error_sym)
@@ -766,6 +771,7 @@ jl_value_t *jl_parse_eval_all(const char *fname, size_t len,
                 jl_lineno = jl_unbox_long(jl_exprarg(form,0));
             else
                 result = jl_toplevel_eval_flex(form, 1);
+            JL_SIGATOMIC_BEGIN();
             ast = cdr_(ast);
         }
     }

src/builtins.c

@@ -194,25 +194,25 @@ JL_CALLABLE(jl_f_throw)
 
 JL_DLLEXPORT void jl_enter_handler(jl_handler_t *eh)
 {
-    JL_SIGATOMIC_BEGIN();
+    // Must have no safepoint
     eh->prev = jl_current_task->eh;
     eh->gcstack = jl_pgcstack;
 #ifdef JULIA_ENABLE_THREADING
     eh->gc_state = jl_gc_state();
     eh->locks_len = jl_current_task->locks.len;
 #endif
+    eh->defer_signal = jl_get_ptls_states()->defer_signal;
     jl_current_task->eh = eh;
-    // TODO: this should really go after setjmp(). see comment in
-    // ctx_switch in task.c.
-    JL_SIGATOMIC_END();
 }
 
 JL_DLLEXPORT void jl_pop_handler(int n)
 {
-    while (n > 0) {
-        jl_eh_restore_state(jl_current_task->eh);
-        n--;
-    }
+    if (__unlikely(n <= 0))
+        return;
+    jl_handler_t *eh = jl_current_task->eh;
+    while (--n > 0)
+        eh = eh->prev;
+    jl_eh_restore_state(eh);
 }
 
 // primitives -----------------------------------------------------------------

src/ccall.cpp

@@ -1243,28 +1243,54 @@ static jl_cgval_t emit_ccall(jl_value_t **args, size_t nargs, jl_codectx_t *ctx)
         assert(!isVa);
         assert(nargt == 0);
         JL_GC_POP();
-#ifdef JULIA_ENABLE_THREADING
-#ifdef LLVM39
-        builder.CreateFence(AtomicOrdering::SequentiallyConsistent, SingleThread);
-#else
-        builder.CreateFence(SequentiallyConsistent, SingleThread);
-#endif
-        Value *addr;
-        if (imaging_mode) {
-            assert(ctx->signalPage);
-            addr = ctx->signalPage;
-        }
-        else {
-            addr = builder.CreateIntToPtr(
-                ConstantInt::get(T_size, (uintptr_t)jl_gc_signal_page), T_pint8);
-        }
-        builder.CreateLoad(addr, true);
-#ifdef LLVM39
-        builder.CreateFence(AtomicOrdering::SequentiallyConsistent, SingleThread);
-#else
-        builder.CreateFence(SequentiallyConsistent, SingleThread);
-#endif
-#endif
+        emit_signal_fence();
+        builder.CreateLoad(ctx->signalPage, true);
+        emit_signal_fence();
+        return ghostValue(jl_void_type);
+    }
+    if (fptr == &jl_sigatomic_begin ||
+        ((!f_lib || (intptr_t)f_lib == 2) && f_name &&
+         strcmp(f_name, "jl_sigatomic_begin") == 0)) {
+        assert(lrt == T_void);
+        assert(!isVa);
+        assert(nargt == 0);
+        JL_GC_POP();
+        Value *pdefer_sig = emit_defer_signal(ctx);
+        Value *defer_sig = builder.CreateLoad(pdefer_sig);
+        defer_sig = builder.CreateAdd(defer_sig,
+                                      ConstantInt::get(T_sigatomic, 1));
+        builder.CreateStore(defer_sig, pdefer_sig);
+        emit_signal_fence();
+        return ghostValue(jl_void_type);
+    }
+    if (fptr == &jl_sigatomic_end ||
+        ((!f_lib || (intptr_t)f_lib == 2) && f_name &&
+         strcmp(f_name, "jl_sigatomic_end") == 0)) {
+        assert(lrt == T_void);
+        assert(!isVa);
+        assert(nargt == 0);
+        JL_GC_POP();
+        Value *pdefer_sig = emit_defer_signal(ctx);
+        Value *defer_sig = builder.CreateLoad(pdefer_sig);
+        emit_signal_fence();
+        error_unless(builder.CreateICmpNE(defer_sig,
+                                          ConstantInt::get(T_sigatomic, 0)),
+                     "sigatomic_end called in non-sigatomic region", ctx);
+        defer_sig = builder.CreateSub(defer_sig,
+                                      ConstantInt::get(T_sigatomic, 1));
+        builder.CreateStore(defer_sig, pdefer_sig);
+        BasicBlock *checkBB = BasicBlock::Create(jl_LLVMContext, "check",
+                                                 ctx->f);
+        BasicBlock *contBB = BasicBlock::Create(jl_LLVMContext, "cont");
+        builder.CreateCondBr(
+            builder.CreateICmpEQ(defer_sig, ConstantInt::get(T_sigatomic, 0)),
+            checkBB, contBB);
+        builder.SetInsertPoint(checkBB);
+        builder.CreateLoad(builder.CreateConstGEP1_32(ctx->signalPage, -1),
+                           true);
+        builder.CreateBr(contBB);
+        ctx->f->getBasicBlockList().push_back(contBB);
+        builder.SetInsertPoint(contBB);
         return ghostValue(jl_void_type);
     }
     if (fptr == (void(*)(void))&jl_is_leaf_type ||

src/cgutils.cpp

@@ -455,7 +455,7 @@ static bool deserves_sret(jl_value_t *dt, Type *T)
 static Value *emit_nthptr_addr(Value *v, ssize_t n)
 {
     return builder.CreateGEP(builder.CreateBitCast(v, T_ppjlvalue),
-                             ConstantInt::get(T_size, (ssize_t)n));
+                             ConstantInt::get(T_size, n));
 }
 
 static Value *emit_nthptr_addr(Value *v, Value *idx)
@@ -477,6 +477,13 @@ static Value *emit_nthptr_recast(Value *v, Value *idx, MDNode *tbaa, Type *ptype
     return tbaa_decorate(tbaa,builder.CreateLoad(builder.CreateBitCast(vptr,ptype), false));
 }
 
+static Value *emit_nthptr_recast(Value *v, ssize_t n, MDNode *tbaa, Type *ptype)
+{
+    // p = (jl_value_t**)v; *(ptype)&p[n]
+    Value *vptr = emit_nthptr_addr(v, n);
+    return tbaa_decorate(tbaa,builder.CreateLoad(builder.CreateBitCast(vptr,ptype), false));
+}
+
 static Value *emit_typeptr_addr(Value *p)
 {
     ssize_t offset = (sizeof(jl_taggedvalue_t) -
@@ -1710,3 +1717,20 @@ static Value *emit_exc_in_transit(jl_codectx_t *ctx)
     Constant *offset = ConstantInt::getSigned(T_int32, offsetof(jl_tls_states_t, exception_in_transit) / sizeof(void*));
     return builder.CreateGEP(pexc_in_transit, ArrayRef<Value*>(offset), "jl_exception_in_transit");
 }
+
+static void emit_signal_fence(void)
+{
+#ifdef LLVM39
+    builder.CreateFence(AtomicOrdering::SequentiallyConsistent, SingleThread);
+#else
+    builder.CreateFence(SequentiallyConsistent, SingleThread);
+#endif
+}
+
+static Value *emit_defer_signal(jl_codectx_t *ctx)
+{
+    Value *ptls = builder.CreateBitCast(ctx->ptlsStates,
+                                        PointerType::get(T_sigatomic, 0));
+    Constant *offset = ConstantInt::getSigned(T_int32, offsetof(jl_tls_states_t, defer_signal) / sizeof(sig_atomic_t));
+    return builder.CreateGEP(ptls, ArrayRef<Value*>(offset), "jl_defer_signal");
+}

src/codegen.cpp

@@ -246,6 +246,7 @@ static IntegerType *T_uint64;
 
 static IntegerType *T_char;
 static IntegerType *T_size;
+static IntegerType *T_sigatomic;
 
 static Type *T_float16;
 static Type *T_float32;
@@ -342,8 +343,6 @@ static GlobalVariable *jltls_states_var;
 // Imaging mode only
 static GlobalVariable *jltls_states_func_ptr = NULL;
 static size_t jltls_states_func_idx = 0;
-static GlobalVariable *jl_gc_signal_page_ptr = NULL;
-static size_t jl_gc_signal_page_idx = 0;
 #endif
 
 // important functions
@@ -576,9 +575,7 @@ typedef struct {
     std::vector<bool> inbounds;
 
     CallInst *ptlsStates;
-#ifdef JULIA_ENABLE_THREADING
     Value *signalPage;
-#endif
 
     llvm::DIBuilder *dbuilder;
     bool debug_enabled;
@@ -1340,6 +1337,7 @@ const jl_value_t *jl_dump_function_asm(void *f, int raw_mc)
         return (jl_value_t*)jl_pchar_to_array((char*)fptr, symsize);
     }
 
+    int8_t gc_state = jl_gc_safe_enter();
     jl_dump_asm_internal(fptr, symsize, slide,
 #ifndef USE_MCJIT
             context,
@@ -1355,6 +1353,7 @@ const jl_value_t *jl_dump_function_asm(void *f, int raw_mc)
 #ifndef LLVM37
     fstream.flush();
 #endif
+    jl_gc_safe_leave(gc_state);
 
     return jl_cstr_to_string(const_cast<char*>(stream.str().c_str()));
 }
@@ -3429,12 +3428,9 @@ static void allocate_gc_frame(BasicBlock *b0, jl_codectx_t *ctx)
 {
     // allocate a placeholder gc instruction
     ctx->ptlsStates = builder.CreateCall(prepare_call(jltls_states_func));
-#ifdef JULIA_ENABLE_THREADING
-    if (imaging_mode) {
-        ctx->signalPage =
-            tbaa_decorate(tbaa_const, builder.CreateLoad(prepare_global(jl_gc_signal_page_ptr)));
-    }
-#endif
+    int nthfield = offsetof(jl_tls_states_t, safepoint) / sizeof(void*);
+    ctx->signalPage = emit_nthptr_recast(ctx->ptlsStates, nthfield, tbaa_const,
+                                         PointerType::get(T_psize, 0));
 }
 
 void jl_codegen_finalize_temp_arg(CallInst *ptlsStates, Type *T_pjlvalue,
@@ -4975,6 +4971,7 @@ static void init_julia_llvm_env(Module *m)
         T_size = T_uint64;
     else
         T_size = T_uint32;
+    T_sigatomic = Type::getIntNTy(jl_LLVMContext, sizeof(sig_atomic_t) * 8);
     T_psize = PointerType::get(T_size, 0);
     T_float16 = Type::getHalfTy(jl_LLVMContext);
     T_float32 = Type::getFloatTy(jl_LLVMContext);
@@ -5165,10 +5162,6 @@ static void init_julia_llvm_env(Module *m)
             jl_emit_sysimg_slot(m, pfunctype, "jl_get_ptls_states.ptr",
                                 (uintptr_t)jl_get_ptls_states_getter(),
                                 jltls_states_func_idx);
-        jl_gc_signal_page_ptr =
-            jl_emit_sysimg_slot(m, T_pint8, "jl_gc_signal_page.ptr",
-                                (uintptr_t)jl_gc_signal_page,
-                                jl_gc_signal_page_idx);
     }
 #endif