Optimize exception frames allocation

* Make llvm-gcroot a ModulePass * Use llvm-gcroot to calculate the minimum number of exception frames necessary.
tkelman · Aug 10, 2016 · 3e0c935 · 3e0c935
1 parent bf05553
commit 3e0c935
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Showing 3 changed files with 270 additions and 67 deletions.
diff --git a/src/codegen.cpp b/src/codegen.cpp
@@ -381,6 +381,7 @@ static Function *gcroot_func;
 static Function *gckill_func;
 static Function *jlcall_frame_func;
 static Function *gcroot_flush_func;
+static Function *except_enter_func;
 
 static std::vector<Type *> two_pvalue_llvmt;
 static std::vector<Type *> three_pvalue_llvmt;
@@ -505,7 +506,6 @@ typedef struct {
     std::vector<bool> ssavalue_assigned;
     std::map<int, jl_arrayvar_t> *arrayvars;
     std::map<int, BasicBlock*> *labels;
-    std::map<int, Value*> *handlers;
     jl_module_t *module;
     jl_lambda_info_t *linfo;
     const char *name;
@@ -3259,18 +3259,7 @@ static jl_cgval_t emit_expr(jl_value_t *expr, jl_codectx_t *ctx)
     else if (head == enter_sym) {
         assert(jl_is_long(args[0]));
         int labl = jl_unbox_long(args[0]);
-        Value *jbuf = builder.CreateGEP((*ctx->handlers)[labl],
-                                        ConstantInt::get(T_size,0));
-        builder.CreateCall(prepare_call(jlenter_func), jbuf);
-#ifndef _OS_WINDOWS_
-#ifdef LLVM37
-        CallInst *sj = builder.CreateCall(prepare_call(setjmp_func), { jbuf, ConstantInt::get(T_int32,0) });
-#else
-        CallInst *sj = builder.CreateCall2(prepare_call(setjmp_func), jbuf, ConstantInt::get(T_int32,0));
-#endif
-#else
-        CallInst *sj = builder.CreateCall(prepare_call(setjmp_func), jbuf);
-#endif
+        CallInst *sj = builder.CreateCall(prepare_call(except_enter_func));
         // We need to mark this on the call site as well. See issue #6757
         sj->setCanReturnTwice();
         Value *isz = builder.CreateICmpEQ(sj, ConstantInt::get(T_int32,0));
@@ -3892,11 +3881,9 @@ static std::unique_ptr<Module> emit_function(jl_lambda_info_t *lam, jl_llvm_func
     //jl_printf(JL_STDOUT, "\n");
     std::map<int, jl_arrayvar_t> arrayvars;
     std::map<int, BasicBlock*> labels;
-    std::map<int, Value*> handlers;
     jl_codectx_t ctx = {};
     ctx.arrayvars = &arrayvars;
     ctx.labels = &labels;
-    ctx.handlers = &handlers;
     ctx.module = lam->def ? lam->def->module : ptls->current_module;
     ctx.linfo = lam;
     ctx.name = jl_symbol_name(lam->def ? lam->def->name : anonymous_sym);
@@ -4329,18 +4316,6 @@ static std::unique_ptr<Module> emit_function(jl_lambda_info_t *lam, jl_llvm_func
     allocate_gc_frame(b0, &ctx);
 
     // step 8. allocate space for exception handler contexts
-    for(i=0; i < stmtslen; i++) {
-        jl_value_t *stmt = jl_array_ptr_ref(stmts,i);
-        if (jl_is_expr(stmt) && ((jl_expr_t*)stmt)->head == enter_sym) {
-            int labl = jl_unbox_long(jl_exprarg(stmt,0));
-            AllocaInst *handlr =
-                builder.CreateAlloca(T_int8,
-                                     ConstantInt::get(T_int32,
-                                                      sizeof(jl_handler_t)));
-            handlr->setAlignment(16);
-            handlers[labl] = handlr;
-        }
-    }
 
     // step 9. allocate local variables slots
     // must be in the first basic block for the llvm mem2reg pass to work
@@ -5533,6 +5508,12 @@ static void init_julia_llvm_env(Module *m)
                                          "julia.gcroot_flush", m);
     add_named_global(gcroot_flush_func, (void*)NULL, /*dllimport*/false);
 
+    except_enter_func = Function::Create(FunctionType::get(T_int32, false),
+                                         Function::ExternalLinkage,
+                                         "julia.except_enter", m);
+    except_enter_func->addFnAttr(Attribute::ReturnsTwice);
+    add_named_global(except_enter_func, (void*)NULL, /*dllimport*/false);
+
     // set up optimization passes
 #ifdef LLVM37
 // No DataLayout pass needed anymore.