| Message ID | m3o9zcgjys.fsf@oc1027705133.ibm.com |
|---|---|
| State | New |
| Headers | show |
On 17-01-12 20:24:27, Andreas Arnez wrote: > diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp > index 9f5fa6c..6bd563a 100644 > --- a/gdb/testsuite/lib/dwarf.exp > +++ b/gdb/testsuite/lib/dwarf.exp > @@ -906,6 +906,25 @@ namespace eval Dwarf { > _op .2byte [lindex $line 1] > } > > + DW_OP_implicit_value { > + set l1 [new_label "value_start"] > + set l2 [new_label "value_end"] > + _op .uleb128 "$l2 - $l1" > + define_label $l1 > + foreach value [lrange $line 1 end] { > + switch -regexp -- $value { > + {^0x[[:xdigit:]]{2}$} {_op .byte $value} Nit: we could also match one digit to simplify the usage. With your patch, we need to use it like this, + {DW_AT_location { + DW_OP_implicit_value 0x01 0x01 0x01 0x01 + } SPECIAL_expr} but if we add "{^0x[[:xdigit:]]{2}$} {_op .byte $value}", the use above can be simplified, + {DW_AT_location { + DW_OP_implicit_value 0x1 0x1 0x1 0x1 + } SPECIAL_expr} > + {^0x[[:xdigit:]]{4}$} {_op .2byte $value} > + {^0x[[:xdigit:]]{8}$} {_op .4byte $value} > + {^0x[[:xdigit:]]{16}$} {_op .8byte $value} > + default { > + error "bad value '$value' in DW_OP_implicit_value" > + } > + } > + } > + define_label $l2 > + } > + During the review, I am trying to use DW_OP_implicit_value in gdb.dwarf2/implptr-64bit.exp, because I think we should use this new added DW_OP as much as we can in existing test case. I get some troubles on using Dwarf::assemble for two cus. I'll let you know once I resolve the issues there.
On Thu, Jan 19 2017, Yao Qi wrote: > Nit: we could also match one digit to simplify the usage. With your > patch, we need to use it like this, > > > + {DW_AT_location { > + DW_OP_implicit_value 0x01 0x01 0x01 0x01 > + } SPECIAL_expr} Right, or in this particular case you could say DW_OP_implicit_value 0x01010101 instead, because the number is endianness-symmetric ;-) > > but if we add "{^0x[[:xdigit:]]{2}$} {_op .byte $value}", the use > above can be simplified, > > + {DW_AT_location { > + DW_OP_implicit_value 0x1 0x1 0x1 0x1 > + } SPECIAL_expr} You probably mean "{^0x[[:xdigit:]]{1,2}$} {_op .byte $value}"? Sure, will do. The idea behind the existing logic is that the resulting immediate value always has half as many bytes as there are hex digits. But for single byte integers I agree that this is a bit picky and the simplification is useful. I would not extend this to multi-byte integers, though, such as allowing 0x123456 or such. > During the review, I am trying to use DW_OP_implicit_value in > gdb.dwarf2/implptr-64bit.exp, because I think we should use this new > added DW_OP as much as we can in existing test case. Sounds good! > I get some troubles on using Dwarf::assemble for two cus. I'll let > you know once I resolve the issues there. OK, let's see how that goes. -- Andreas
Andreas posted a patch https://sourceware.org/ml/gdb-patches/2017-01/msg00251.html and added DW_OP_implicit_value in dwarf assembler. I find DW_OP_implicit_value can be used in gdb.dwarf2/implptr-64bit.exp, so that we can remove implptr-64bit.S and use the generated .S file instead. Patch 1 fixes a minor bug in dwarf assembler, and patch 2 does the major work. Run gdb.dwarf2/*.exp on i686-pc-linux-gnu. There is no change in the .S files generated by dwarf assembler. *** BLURB HERE *** Yao Qi (2): Handle DW_OP_GNU_implicit_pointer in dwarf assembler Use dwarf assembler in gdb.dwarf2/implptr-64bit.exp gdb/testsuite/gdb.dwarf2/implptr-64bit.S | 226 ----------------------------- gdb/testsuite/gdb.dwarf2/implptr-64bit.exp | 118 +++++++++++++-- gdb/testsuite/lib/dwarf.exp | 46 +++++- 3 files changed, 153 insertions(+), 237 deletions(-) delete mode 100644 gdb/testsuite/gdb.dwarf2/implptr-64bit.S
On 17-01-12 20:24:27, Andreas Arnez wrote: > diff --git a/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp b/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp > index c28dcca..808f983 100644 > --- a/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp > +++ b/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp > @@ -45,7 +45,7 @@ gdb_test_multiple $test $test { > -re ":\[ \t\]*0xaa551234\r\n$gdb_prompt $" { > # big endian > pass $test > - gdb_test "p/x implicit4to2" " = 0x3344" > + gdb_test "p/x implicit4to2" " = 0x1122" > gdb_test "p/x implicit4to4" " = 0x11223344" It takes me a while to understand this. I am wondering is it a valid test case? how does compiler generate a DIE for a 2-byte variable from a 4-byte implicit value. DWARF spec isn't clear on this case to me. It has nothing to do with your patch, but I just raise this question when I read your patch. > +# Byte-aligned objects with simple location descriptions. > +switch $endian { big {set val 0x345678} little {set val 0x785634} } > +gdb_test "print/x def_implicit_s" " = \\{a = 0x12, b = $val\\}" > +gdb_test "print/x def_implicit_s.b" " = $val" > +gdb_test "print/x def_implicit_a" \ > + " = \\{0x1, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78, 0x89\\}" All these values are from debug information rather than inferior memory, does it make sense to run these tests above with both big and little endianess? Otherwise, patch is good to me.
On Wed, Jan 25 2017, Yao Qi wrote: > On 17-01-12 20:24:27, Andreas Arnez wrote: >> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp b/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp >> index c28dcca..808f983 100644 >> --- a/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp >> +++ b/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp >> @@ -45,7 +45,7 @@ gdb_test_multiple $test $test { >> -re ":\[ \t\]*0xaa551234\r\n$gdb_prompt $" { >> # big endian >> pass $test >> - gdb_test "p/x implicit4to2" " = 0x3344" >> + gdb_test "p/x implicit4to2" " = 0x1122" >> gdb_test "p/x implicit4to4" " = 0x11223344" > > It takes me a while to understand this. I am wondering is it a valid > test case? how does compiler generate a DIE for a 2-byte variable > from a 4-byte implicit value. AFAIK never. I don't know why a compiler should emit a larger immediate value than necessary. So this is an artificial test. > DWARF spec isn't clear on this case to me. Right, DWARF does not specify this. Even so, we may want GDB to exhibit defined behavior for such corner cases as well. I probably wouldn't have added such a test, but I didn't want remove it either, because it could be considered useful in the sense that it tests GDB's "implementation-defined" behavior for this case. > It has nothing to do with your patch, but I just raise this > question when I read your patch. > >> +# Byte-aligned objects with simple location descriptions. >> +switch $endian { big {set val 0x345678} little {set val 0x785634} } >> +gdb_test "print/x def_implicit_s" " = \\{a = 0x12, b = $val\\}" >> +gdb_test "print/x def_implicit_s.b" " = $val" >> +gdb_test "print/x def_implicit_a" \ >> + " = \\{0x1, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78, 0x89\\}" > > All these values are from debug information rather than inferior memory, > does it make sense to run these tests above with both big and little > endianess? I've tried, but I don't know to make it work. Switching to the opposite endianness affects more than just the byte order of variable contents; the variables are not even found any more. Any idea? > Otherwise, patch is good to me. Thanks! -- Andreas
On Fri, Jan 27 2017, Andreas Arnez wrote: > On Wed, Jan 25 2017, Yao Qi wrote: > [...] >> All these values are from debug information rather than inferior memory, >> does it make sense to run these tests above with both big and little >> endianess? > > I've tried, but I don't know to make it work. Switching to the opposite > endianness affects more than just the byte order of variable contents; > the variables are not even found any more. Any idea? > >> Otherwise, patch is good to me. Is it OK then to push the patch? The logic for testing both little- and big-endian byte order can still be added later, right? -- Andreas
On Wed, Feb 1, 2017 at 9:09 AM, Andreas Arnez <arnez@linux.vnet.ibm.com> wrote: >> >> I've tried, but I don't know to make it work. Switching to the opposite >> endianness affects more than just the byte order of variable contents; >> the variables are not even found any more. Any idea? >> >>> Otherwise, patch is good to me. > > Is it OK then to push the patch? The logic for testing both little- and > big-endian byte order can still be added later, right? > Hi Andreas, Yes, the patch can be pushed in. I can take a look at the test for both endianess later.
diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c index 7fca76b..a592b66 100644 --- a/gdb/dwarf2loc.c +++ b/gdb/dwarf2loc.c @@ -2442,28 +2442,15 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame, case DWARF_VALUE_LITERAL: { bfd_byte *contents; - const bfd_byte *ldata; - size_t n = ctx.len; + size_t n = TYPE_LENGTH (type); - if (byte_offset + TYPE_LENGTH (type) > n) + if (byte_offset + n > ctx.len) invalid_synthetic_pointer (); free_values.free_to_mark (); retval = allocate_value (type); contents = value_contents_raw (retval); - - ldata = ctx.data + byte_offset; - n -= byte_offset; - - if (n > TYPE_LENGTH (type)) - { - struct gdbarch *objfile_gdbarch = get_objfile_arch (objfile); - - if (gdbarch_byte_order (objfile_gdbarch) == BFD_ENDIAN_BIG) - ldata += n - TYPE_LENGTH (type); - n = TYPE_LENGTH (type); - } - memcpy (contents, ldata, n); + memcpy (contents, ctx.data + byte_offset, n); } break; diff --git a/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp b/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp index c28dcca..808f983 100644 --- a/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp +++ b/gdb/testsuite/gdb.dwarf2/dw2-op-stack-value.exp @@ -45,7 +45,7 @@ gdb_test_multiple $test $test { -re ":\[ \t\]*0xaa551234\r\n$gdb_prompt $" { # big endian pass $test - gdb_test "p/x implicit4to2" " = 0x3344" + gdb_test "p/x implicit4to2" " = 0x1122" gdb_test "p/x implicit4to4" " = 0x11223344" } -re ":\[ \t\]*0x\[0-9a-f\]{8}\r\n$gdb_prompt $" { diff --git a/gdb/testsuite/gdb.dwarf2/nonvar-access.exp b/gdb/testsuite/gdb.dwarf2/nonvar-access.exp index 506ff9e..f47df70 100644 --- a/gdb/testsuite/gdb.dwarf2/nonvar-access.exp +++ b/gdb/testsuite/gdb.dwarf2/nonvar-access.exp @@ -31,14 +31,23 @@ Dwarf::assemble $asm_file { compile_unit { {DW_AT_name main.c} } { - declare_labels int_type_label short_type_label - declare_labels struct_s_label struct_t_label + declare_labels int_type_label char_type_label \ + struct_s_label struct_t_label array_a9_label \ + char_ptr_label implicit_a_label int_type_label: base_type { {name "int"} {encoding @DW_ATE_signed} {byte_size 4 DW_FORM_sdata} } + char_type_label: base_type { + {name "char"} + {encoding @DW_ATE_unsigned} + {byte_size 1 DW_FORM_sdata} + } + char_ptr_label: pointer_type { + {type :$char_type_label} + } struct_s_label: structure_type { {name s} @@ -76,20 +85,32 @@ Dwarf::assemble $asm_file { } } + array_a9_label: array_type { + {type :$char_type_label} + } { + subrange_type { + {type :$int_type_label} + {upper_bound 8 DW_FORM_udata} + } + } + DW_TAG_subprogram { {name main} {DW_AT_external 1 flag} {low_pc [gdb_target_symbol main] DW_FORM_addr} {high_pc [gdb_target_symbol main]+0x10000 DW_FORM_addr} } { + # Simple variable without location. DW_TAG_variable { {name undef_int} {type :$int_type_label} } + # Struct variable without location. DW_TAG_variable { {name undef_s} {type :$struct_s_label} } + # Composite location: byte-aligned pieces. DW_TAG_variable { {name def_s} {type :$struct_s_label} @@ -102,6 +123,7 @@ Dwarf::assemble $asm_file { bit_piece 24 0 } SPECIAL_expr} } + # Composite location: non-byte-aligned pieces. DW_TAG_variable { {name def_t} {type :$struct_t_label} @@ -114,6 +136,32 @@ Dwarf::assemble $asm_file { bit_piece 23 0 } SPECIAL_expr} } + # Implicit location: immediate value. + DW_TAG_variable { + {name def_implicit_s} + {type :$struct_s_label} + {location { + implicit_value 0x12 0x34 0x56 0x78 + } SPECIAL_expr} + } + # Implicit location: immediate value for whole array, with + # excess bytes. + implicit_a_label: DW_TAG_variable { + {name def_implicit_a} + {type :$array_a9_label} + {location { + implicit_value 0x01 0x12 0x23 0x34 0x45 \ + 0x56 0x67 0x78 0x89 0x9a 0xab + } SPECIAL_expr} + } + # Implicit pointer into immediate value. + DW_TAG_variable { + {name implicit_a_ptr} + {type :$char_ptr_label} + {location { + GNU_implicit_pointer $implicit_a_label 5 + } SPECIAL_expr} + } } } } @@ -128,7 +176,33 @@ if ![runto_main] { return -1 } +# Determine endianness. +set endian "little" +gdb_test_multiple "show endian" "determine endianness" { + -re ".* (big|little) endian.*$gdb_prompt $" { + set endian $expect_out(1,string) + pass "endianness: $endian" + } +} + +# Byte-aligned objects with simple location descriptions. +switch $endian { big {set val 0x345678} little {set val 0x785634} } +gdb_test "print/x def_implicit_s" " = \\{a = 0x12, b = $val\\}" +gdb_test "print/x def_implicit_s.b" " = $val" +gdb_test "print/x def_implicit_a" \ + " = \\{0x1, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78, 0x89\\}" +gdb_test "print/x def_implicit_a\[5\]" " = 0x56" +gdb_test "print/x *(char (*)\[5\]) implicit_a_ptr" \ + " = \\{0x56, 0x67, 0x78, 0x89, 0x9a\\}" + +# Byte-aligned fields, pieced together from DWARF stack values. gdb_test "print def_s" " = \\{a = 0, b = -1\\}" + +# Non-byte-aligned fields, pieced together from DWARF stack values. gdb_test "print def_t" " = \\{a = 0, b = -1\\}" + +# Simple variable without location. gdb_test "print undef_int" " = <optimized out>" + +# Member of a structure without location. gdb_test "print undef_s.a" " = <optimized out>" diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp index 9f5fa6c..6bd563a 100644 --- a/gdb/testsuite/lib/dwarf.exp +++ b/gdb/testsuite/lib/dwarf.exp @@ -906,6 +906,25 @@ namespace eval Dwarf { _op .2byte [lindex $line 1] } + DW_OP_implicit_value { + set l1 [new_label "value_start"] + set l2 [new_label "value_end"] + _op .uleb128 "$l2 - $l1" + define_label $l1 + foreach value [lrange $line 1 end] { + switch -regexp -- $value { + {^0x[[:xdigit:]]{2}$} {_op .byte $value} + {^0x[[:xdigit:]]{4}$} {_op .2byte $value} + {^0x[[:xdigit:]]{8}$} {_op .4byte $value} + {^0x[[:xdigit:]]{16}$} {_op .8byte $value} + default { + error "bad value '$value' in DW_OP_implicit_value" + } + } + } + define_label $l2 + } + DW_OP_GNU_implicit_pointer { if {[llength $line] != 3} { error "usage: DW_OP_GNU_implicit_pointer LABEL OFFSET"