Inline jl_sigatomic_begin and jl_sigatomic_end

Author: yuyichao

src/ccall.cpp

@@ -1243,17 +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 LLVM39
-        builder.CreateFence(AtomicOrdering::SequentiallyConsistent, SingleThread);
-#else
-        builder.CreateFence(SequentiallyConsistent, SingleThread);
-#endif
+        emit_signal_fence();
         builder.CreateLoad(ctx->signalPage, true);
-#ifdef LLVM39
-        builder.CreateFence(AtomicOrdering::SequentiallyConsistent, SingleThread);
-#else
-        builder.CreateFence(SequentiallyConsistent, SingleThread);
-#endif
+        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

@@ -1717,3 +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;
@@ -4970,6 +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);