From c845cfe1af6a72609e04a68b967f2b919599b32b Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Thu, 21 Mar 2013 18:35:39 +0100 Subject: [PATCH] re PR debug/55608 (Debug info quality regressions with file scope vars) PR debug/55608 * dwarf2out.c (tree_add_const_value_attribute): Call ggc_free (array) on failure. (resolve_one_addr): Fail if referenced STRING_CST hasn't been written. (string_cst_pool_decl): New function. (optimize_one_addr_into_implicit_ptr): New function. (resolve_addr_in_expr): Optimize DWARF location expression DW_OP_addr DW_OP_stack_value where DW_OP_addr refers to some variable which doesn't live in memory, but has DW_AT_location or DW_AT_const_value, or refers to a string literal, into DW_OP_GNU_implicit_pointer. (optimize_location_into_implicit_ptr): New function. (resolve_addr): If removing DW_AT_location of a variable because it was DW_OP_addr of address of the variable, but the variable doesn't live in memory, try to emit const value attribute for the initializer. From-SVN: r196886 --- gcc/ChangeLog | 18 ++++ gcc/dwarf2out.c | 221 +++++++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 227 insertions(+), 12 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 3992373c395..b8a1b19e699 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,21 @@ +2013-03-21 Jakub Jelinek + + PR debug/55608 + * dwarf2out.c (tree_add_const_value_attribute): Call ggc_free (array) + on failure. + (resolve_one_addr): Fail if referenced STRING_CST hasn't been written. + (string_cst_pool_decl): New function. + (optimize_one_addr_into_implicit_ptr): New function. + (resolve_addr_in_expr): Optimize DWARF location expression + DW_OP_addr DW_OP_stack_value where DW_OP_addr refers to some variable + which doesn't live in memory, but has DW_AT_location or + DW_AT_const_value, or refers to a string literal, into + DW_OP_GNU_implicit_pointer. + (optimize_location_into_implicit_ptr): New function. + (resolve_addr): If removing DW_AT_location of a variable because + it was DW_OP_addr of address of the variable, but the variable doesn't + live in memory, try to emit const value attribute for the initializer. + 2013-03-21 Marc Glisse * tree.h (VECTOR_TYPE_P): New macro. diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c index a5d5dc408a2..9be77286dac 100644 --- a/gcc/dwarf2out.c +++ b/gcc/dwarf2out.c @@ -15527,6 +15527,7 @@ tree_add_const_value_attribute (dw_die_ref die, tree t) add_AT_vec (die, DW_AT_const_value, size, 1, array); return true; } + ggc_free (array); } } return false; @@ -22494,6 +22495,10 @@ resolve_one_addr (rtx *addr, void *data ATTRIBUTE_UNUSED) if (!rtl || !MEM_P (rtl)) return 1; rtl = XEXP (rtl, 0); + if (GET_CODE (rtl) == SYMBOL_REF + && SYMBOL_REF_DECL (rtl) + && !TREE_ASM_WRITTEN (SYMBOL_REF_DECL (rtl))) + return 1; vec_safe_push (used_rtx_array, rtl); *addr = rtl; return 0; @@ -22518,6 +22523,103 @@ resolve_one_addr (rtx *addr, void *data ATTRIBUTE_UNUSED) return 0; } +/* For STRING_CST, return SYMBOL_REF of its constant pool entry, + if possible, and create DW_TAG_dwarf_procedure that can be referenced + from DW_OP_GNU_implicit_pointer if the string hasn't been seen yet. */ + +static rtx +string_cst_pool_decl (tree t) +{ + rtx rtl = output_constant_def (t, 1); + unsigned char *array; + dw_loc_descr_ref l; + tree decl; + size_t len; + dw_die_ref ref; + + if (!rtl || !MEM_P (rtl)) + return NULL_RTX; + rtl = XEXP (rtl, 0); + if (GET_CODE (rtl) != SYMBOL_REF + || SYMBOL_REF_DECL (rtl) == NULL_TREE) + return NULL_RTX; + + decl = SYMBOL_REF_DECL (rtl); + if (!lookup_decl_die (decl)) + { + len = TREE_STRING_LENGTH (t); + vec_safe_push (used_rtx_array, rtl); + ref = new_die (DW_TAG_dwarf_procedure, comp_unit_die (), decl); + array = (unsigned char *) ggc_alloc_atomic (len); + memcpy (array, TREE_STRING_POINTER (t), len); + l = new_loc_descr (DW_OP_implicit_value, len, 0); + l->dw_loc_oprnd2.val_class = dw_val_class_vec; + l->dw_loc_oprnd2.v.val_vec.length = len; + l->dw_loc_oprnd2.v.val_vec.elt_size = 1; + l->dw_loc_oprnd2.v.val_vec.array = array; + add_AT_loc (ref, DW_AT_location, l); + equate_decl_number_to_die (decl, ref); + } + return rtl; +} + +/* Helper function of resolve_addr_in_expr. LOC is + a DW_OP_addr followed by DW_OP_stack_value, either at the start + of exprloc or after DW_OP_{,bit_}piece, and val_addr can't be + resolved. Replace it (both DW_OP_addr and DW_OP_stack_value) + with DW_OP_GNU_implicit_pointer if possible + and return true, if unsuccesful, return false. */ + +static bool +optimize_one_addr_into_implicit_ptr (dw_loc_descr_ref loc) +{ + rtx rtl = loc->dw_loc_oprnd1.v.val_addr; + HOST_WIDE_INT offset = 0; + dw_die_ref ref = NULL; + tree decl; + + if (GET_CODE (rtl) == CONST + && GET_CODE (XEXP (rtl, 0)) == PLUS + && CONST_INT_P (XEXP (XEXP (rtl, 0), 1))) + { + offset = INTVAL (XEXP (XEXP (rtl, 0), 1)); + rtl = XEXP (XEXP (rtl, 0), 0); + } + if (GET_CODE (rtl) == CONST_STRING) + { + size_t len = strlen (XSTR (rtl, 0)) + 1; + tree t = build_string (len, XSTR (rtl, 0)); + tree tlen = size_int (len - 1); + + TREE_TYPE (t) + = build_array_type (char_type_node, build_index_type (tlen)); + rtl = string_cst_pool_decl (t); + if (!rtl) + return false; + } + if (GET_CODE (rtl) == SYMBOL_REF && SYMBOL_REF_DECL (rtl)) + { + decl = SYMBOL_REF_DECL (rtl); + if (TREE_CODE (decl) == VAR_DECL && !DECL_EXTERNAL (decl)) + { + ref = lookup_decl_die (decl); + if (ref && (get_AT (ref, DW_AT_location) + || get_AT (ref, DW_AT_const_value))) + { + loc->dw_loc_opc = DW_OP_GNU_implicit_pointer; + loc->dw_loc_oprnd1.val_class = dw_val_class_die_ref; + loc->dw_loc_oprnd1.val_entry = NULL; + loc->dw_loc_oprnd1.v.val_die_ref.die = ref; + loc->dw_loc_oprnd1.v.val_die_ref.external = 0; + loc->dw_loc_next = loc->dw_loc_next->dw_loc_next; + loc->dw_loc_oprnd2.v.val_int = offset; + return true; + } + } + } + return false; +} + /* Helper function for resolve_addr, handle one location expression, return false if at least one CONST_STRING or SYMBOL_REF in the location list couldn't be resolved. */ @@ -22526,23 +22628,31 @@ static bool resolve_addr_in_expr (dw_loc_descr_ref loc) { dw_loc_descr_ref keep = NULL; - for (; loc; loc = loc->dw_loc_next) + for (dw_loc_descr_ref prev = NULL; loc; prev = loc, loc = loc->dw_loc_next) switch (loc->dw_loc_opc) { case DW_OP_addr: if (resolve_one_addr (&loc->dw_loc_oprnd1.v.val_addr, NULL)) - return false; + { + if ((prev == NULL + || prev->dw_loc_opc == DW_OP_piece + || prev->dw_loc_opc == DW_OP_bit_piece) + && loc->dw_loc_next + && loc->dw_loc_next->dw_loc_opc == DW_OP_stack_value + && !dwarf_strict + && optimize_one_addr_into_implicit_ptr (loc)) + break; + return false; + } break; case DW_OP_GNU_addr_index: case DW_OP_GNU_const_index: - { - if ((loc->dw_loc_opc == DW_OP_GNU_addr_index - || (loc->dw_loc_opc == DW_OP_GNU_const_index && loc->dtprel)) - && resolve_one_addr (&loc->dw_loc_oprnd1.val_entry->addr.rtl, - NULL)) - return false; - } - break; + if ((loc->dw_loc_opc == DW_OP_GNU_addr_index + || (loc->dw_loc_opc == DW_OP_GNU_const_index && loc->dtprel)) + && resolve_one_addr (&loc->dw_loc_oprnd1.val_entry->addr.rtl, + NULL)) + return false; + break; case DW_OP_const4u: case DW_OP_const8u: if (loc->dtprel @@ -22637,6 +22747,80 @@ resolve_addr_in_expr (dw_loc_descr_ref loc) return true; } +/* Helper function of resolve_addr. DIE had DW_AT_location of + DW_OP_addr alone, which referred to DECL in DW_OP_addr's operand + and DW_OP_addr couldn't be resolved. resolve_addr has already + removed the DW_AT_location attribute. This function attempts to + add a new DW_AT_location attribute with DW_OP_GNU_implicit_pointer + to it or DW_AT_const_value attribute, if possible. */ + +static void +optimize_location_into_implicit_ptr (dw_die_ref die, tree decl) +{ + if (TREE_CODE (decl) != VAR_DECL + || lookup_decl_die (decl) != die + || DECL_EXTERNAL (decl) + || !TREE_STATIC (decl) + || DECL_INITIAL (decl) == NULL_TREE + || DECL_P (DECL_INITIAL (decl)) + || get_AT (die, DW_AT_const_value)) + return; + + tree init = DECL_INITIAL (decl); + HOST_WIDE_INT offset = 0; + /* For variables that have been optimized away and thus + don't have a memory location, see if we can emit + DW_AT_const_value instead. */ + if (tree_add_const_value_attribute (die, init)) + return; + if (dwarf_strict) + return; + /* If init is ADDR_EXPR or POINTER_PLUS_EXPR of ADDR_EXPR, + and ADDR_EXPR refers to a decl that has DW_AT_location or + DW_AT_const_value (but isn't addressable, otherwise + resolving the original DW_OP_addr wouldn't fail), see if + we can add DW_OP_GNU_implicit_pointer. */ + STRIP_NOPS (init); + if (TREE_CODE (init) == POINTER_PLUS_EXPR + && host_integerp (TREE_OPERAND (init, 1), 0)) + { + offset = tree_low_cst (TREE_OPERAND (init, 1), 0); + init = TREE_OPERAND (init, 0); + STRIP_NOPS (init); + } + if (TREE_CODE (init) != ADDR_EXPR) + return; + if ((TREE_CODE (TREE_OPERAND (init, 0)) == STRING_CST + && !TREE_ASM_WRITTEN (TREE_OPERAND (init, 0))) + || (TREE_CODE (TREE_OPERAND (init, 0)) == VAR_DECL + && !DECL_EXTERNAL (TREE_OPERAND (init, 0)) + && TREE_OPERAND (init, 0) != decl)) + { + dw_die_ref ref; + dw_loc_descr_ref l; + + if (TREE_CODE (TREE_OPERAND (init, 0)) == STRING_CST) + { + rtx rtl = string_cst_pool_decl (TREE_OPERAND (init, 0)); + if (!rtl) + return; + decl = SYMBOL_REF_DECL (rtl); + } + else + decl = TREE_OPERAND (init, 0); + ref = lookup_decl_die (decl); + if (ref == NULL + || (!get_AT (ref, DW_AT_location) + && !get_AT (ref, DW_AT_const_value))) + return; + l = new_loc_descr (DW_OP_GNU_implicit_pointer, 0, offset); + l->dw_loc_oprnd1.val_class = dw_val_class_die_ref; + l->dw_loc_oprnd1.v.val_die_ref.die = ref; + l->dw_loc_oprnd1.v.val_die_ref.external = 0; + add_AT_loc (die, DW_AT_location, l); + } +} + /* Resolve DW_OP_addr and DW_AT_const_value CONST_STRING arguments to an address in .rodata section if the string literal is emitted there, or remove the containing location list or replace DW_AT_const_value @@ -22723,8 +22907,21 @@ resolve_addr (dw_die_ref die) || l->dw_loc_next != NULL) && !resolve_addr_in_expr (l)) { - if (dwarf_split_debug_info) - remove_loc_list_addr_table_entries (l); + if (dwarf_split_debug_info) + remove_loc_list_addr_table_entries (l); + if (l != NULL + && l->dw_loc_next == NULL + && l->dw_loc_opc == DW_OP_addr + && GET_CODE (l->dw_loc_oprnd1.v.val_addr) == SYMBOL_REF + && SYMBOL_REF_DECL (l->dw_loc_oprnd1.v.val_addr) + && a->dw_attr == DW_AT_location) + { + tree decl = SYMBOL_REF_DECL (l->dw_loc_oprnd1.v.val_addr); + remove_AT (die, a->dw_attr); + ix--; + optimize_location_into_implicit_ptr (die, decl); + break; + } remove_AT (die, a->dw_attr); ix--; } -- 2.30.2