From df87044fd6588452755014d5909e0db1b776deb2 Mon Sep 17 00:00:00 2001 From: Andrew Kelley Date: Thu, 14 Feb 2019 16:10:12 -0500 Subject: [PATCH] omit nonnull attribute for C pointers See #1059 --- src/analyze.cpp | 4 ++++ src/analyze.hpp | 1 + src/codegen.cpp | 19 ++++++++++++++++--- src/target.cpp | 4 ++++ src/target.hpp | 1 + 5 files changed, 26 insertions(+), 3 deletions(-) diff --git a/src/analyze.cpp b/src/analyze.cpp index 90ce3d3371..55deafb3a8 100644 --- a/src/analyze.cpp +++ b/src/analyze.cpp @@ -4100,6 +4100,10 @@ ZigType *get_codegen_ptr_type(ZigType *type) { return ty; } +bool type_is_nonnull_ptr(ZigType *type) { + return type_is_codegen_pointer(type) && !ptr_allows_addr_zero(type); +} + bool type_is_codegen_pointer(ZigType *type) { return get_codegen_ptr_type(type) == type; } diff --git a/src/analyze.hpp b/src/analyze.hpp index 50e841baa1..845fb62534 100644 --- a/src/analyze.hpp +++ b/src/analyze.hpp @@ -46,6 +46,7 @@ void find_libc_lib_path(CodeGen *g); bool type_has_bits(ZigType *type_entry); bool type_allowed_in_extern(CodeGen *g, ZigType *type_entry); bool ptr_allows_addr_zero(ZigType *ptr_type); +bool type_is_nonnull_ptr(ZigType *type); ImportTableEntry *add_source_file(CodeGen *g, PackageTableEntry *package, Buf *abs_full_path, Buf *source_code); diff --git a/src/codegen.cpp b/src/codegen.cpp index dbb13ca885..bae9abe06d 100644 --- a/src/codegen.cpp +++ b/src/codegen.cpp @@ -617,9 +617,10 @@ static LLVMValueRef fn_llvm_value(CodeGen *g, ZigFn *fn_table_entry) { unsigned init_gen_i = 0; if (!type_has_bits(return_type)) { // nothing to do - } else if (type_is_codegen_pointer(return_type)) { + } else if (type_is_nonnull_ptr(return_type)) { addLLVMAttr(fn_table_entry->llvm_value, 0, "nonnull"); } else if (want_first_arg_sret(g, &fn_type->data.fn.fn_type_id)) { + // Sret pointers must not be address 0 addLLVMArgAttr(fn_table_entry->llvm_value, 0, "nonnull"); addLLVMArgAttr(fn_table_entry->llvm_value, 0, "sret"); if (cc_want_sret_attr(cc)) { @@ -637,6 +638,8 @@ static LLVMValueRef fn_llvm_value(CodeGen *g, ZigFn *fn_table_entry) { uint32_t err_ret_trace_arg_index = get_err_ret_trace_arg_index(g, fn_table_entry); if (err_ret_trace_arg_index != UINT32_MAX) { + // Error return trace memory is in the stack, which is impossible to be at address 0 + // on any architecture. addLLVMArgAttr(fn_table_entry->llvm_value, (unsigned)err_ret_trace_arg_index, "nonnull"); } @@ -1246,6 +1249,8 @@ static LLVMValueRef get_add_error_return_trace_addr_fn(CodeGen *g) { LLVMSetFunctionCallConv(fn_val, get_llvm_cc(g, CallingConventionUnspecified)); addLLVMFnAttr(fn_val, "nounwind"); add_uwtable_attr(g, fn_val); + // Error return trace memory is in the stack, which is impossible to be at address 0 + // on any architecture. addLLVMArgAttr(fn_val, (unsigned)0, "nonnull"); if (g->build_mode == BuildModeDebug) { ZigLLVMAddFunctionAttr(fn_val, "no-frame-pointer-elim", "true"); @@ -1320,9 +1325,13 @@ static LLVMValueRef get_merge_err_ret_traces_fn_val(CodeGen *g) { LLVMSetFunctionCallConv(fn_val, get_llvm_cc(g, CallingConventionUnspecified)); addLLVMFnAttr(fn_val, "nounwind"); add_uwtable_attr(g, fn_val); + // Error return trace memory is in the stack, which is impossible to be at address 0 + // on any architecture. addLLVMArgAttr(fn_val, (unsigned)0, "nonnull"); addLLVMArgAttr(fn_val, (unsigned)0, "noalias"); addLLVMArgAttr(fn_val, (unsigned)0, "writeonly"); + // Error return trace memory is in the stack, which is impossible to be at address 0 + // on any architecture. addLLVMArgAttr(fn_val, (unsigned)1, "nonnull"); addLLVMArgAttr(fn_val, (unsigned)1, "noalias"); addLLVMArgAttr(fn_val, (unsigned)1, "readonly"); @@ -1450,6 +1459,8 @@ static LLVMValueRef get_return_err_fn(CodeGen *g) { LLVMSetFunctionCallConv(fn_val, get_llvm_cc(g, CallingConventionUnspecified)); addLLVMFnAttr(fn_val, "nounwind"); add_uwtable_attr(g, fn_val); + // Error return trace memory is in the stack, which is impossible to be at address 0 + // on any architecture. addLLVMArgAttr(fn_val, (unsigned)0, "nonnull"); if (g->build_mode == BuildModeDebug) { ZigLLVMAddFunctionAttr(fn_val, "no-frame-pointer-elim", "true"); @@ -2051,7 +2062,7 @@ static bool iter_function_params_c_abi(CodeGen *g, ZigType *fn_type, FnWalk *fn_ case FnWalkIdAttrs: { ZigType *ptr_type = get_codegen_ptr_type(ty); if (ptr_type != nullptr) { - if (ty->id != ZigTypeIdOptional) { + if (type_is_nonnull_ptr(ty)) { addLLVMArgAttr(llvm_fn, fn_walk->data.attrs.gen_i, "nonnull"); } if (ptr_type->data.pointer.is_const) { @@ -2095,6 +2106,7 @@ static bool iter_function_params_c_abi(CodeGen *g, ZigType *fn_type, FnWalk *fn_ assert(handle_is_ptr(ty)); switch (fn_walk->id) { case FnWalkIdAttrs: + // arrays passed to C ABI functions may not be at address 0 addLLVMArgAttr(llvm_fn, fn_walk->data.attrs.gen_i, "nonnull"); addLLVMArgAttrInt(llvm_fn, fn_walk->data.attrs.gen_i, "align", get_abi_alignment(g, ty)); fn_walk->data.attrs.gen_i += 1; @@ -2134,6 +2146,7 @@ static bool iter_function_params_c_abi(CodeGen *g, ZigType *fn_type, FnWalk *fn_ case FnWalkIdAttrs: addLLVMArgAttr(llvm_fn, fn_walk->data.attrs.gen_i, "byval"); addLLVMArgAttrInt(llvm_fn, fn_walk->data.attrs.gen_i, "align", get_abi_alignment(g, ty)); + // Byvalue parameters must not have address 0 addLLVMArgAttr(llvm_fn, fn_walk->data.attrs.gen_i, "nonnull"); fn_walk->data.attrs.gen_i += 1; break; @@ -2266,7 +2279,7 @@ void walk_function_params(CodeGen *g, ZigType *fn_type, FnWalk *fn_walk) { if ((param_type->id == ZigTypeIdPointer && param_type->data.pointer.is_const) || is_byval) { addLLVMArgAttr(llvm_fn, (unsigned)gen_index, "readonly"); } - if (param_type->id == ZigTypeIdPointer) { + if (type_is_nonnull_ptr(param_type)) { addLLVMArgAttr(llvm_fn, (unsigned)gen_index, "nonnull"); } break; diff --git a/src/target.cpp b/src/target.cpp index 6fea79518c..b1434c6871 100644 --- a/src/target.cpp +++ b/src/target.cpp @@ -807,6 +807,10 @@ uint32_t target_c_type_size_in_bits(const ZigTarget *target, CIntType id) { zig_unreachable(); } +bool target_allows_addr_zero(const ZigTarget *target) { + return target->os == OsFreestanding; +} + const char *target_o_file_ext(ZigTarget *target) { if (target->env_type == ZigLLVM_MSVC || target->os == OsWindows || target->os == OsUefi) { return ".obj"; diff --git a/src/target.hpp b/src/target.hpp index a87b12351a..99d1cadf56 100644 --- a/src/target.hpp +++ b/src/target.hpp @@ -135,5 +135,6 @@ bool target_can_exec(const ZigTarget *host_target, const ZigTarget *guest_target ZigLLVM_OSType get_llvm_os_type(Os os_type); bool target_is_arm(const ZigTarget *target); +bool target_allows_addr_zero(const ZigTarget *target); #endif