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From: Simon Marchi <simark@sourceware.org> To: gdb-cvs@sourceware.org Subject: [binutils-gdb] gdb/testsuite: add test for negative subrange bounds with unsigned form Date: Fri, 20 Jan 2023 16:51:59 +0000 (GMT) [thread overview] Message-ID: <20230120165159.BFB4C389850C@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=173628ae6896d4cadddcb0c3034206d7cc9fb19a commit 173628ae6896d4cadddcb0c3034206d7cc9fb19a Author: Simon Marchi <simon.marchi@polymtl.ca> Date: Fri Jan 20 11:41:08 2023 -0500 gdb/testsuite: add test for negative subrange bounds with unsigned form I am looking at this code [1]: /* Normally, the DWARF producers are expected to use a signed constant form (Eg. DW_FORM_sdata) to express negative bounds. But this is unfortunately not always the case, as witnessed with GCC, for instance, where the ambiguous DW_FORM_dataN form is used instead. To work around that ambiguity, we treat the bounds as signed, and thus sign-extend their values, when the base type is signed. */ negative_mask = -((ULONGEST) 1 << (base_type->length () * TARGET_CHAR_BIT - 1)); if (low.kind () == PROP_CONST && !base_type->is_unsigned () && (low.const_val () & negative_mask)) low.set_const_val (low.const_val () | negative_mask); if (high.kind () == PROP_CONST && !base_type->is_unsigned () && (high.const_val () & negative_mask)) high.set_const_val (high.const_val () | negative_mask); Nothing in the testsuite seems to exercise it, as when I remove it, all of gdb.dwarf2 still passes. And tests in other directories would be compiler-dependent, so would rely on having a buggy compiler. Update gdb.dwarf2/subrange.exp to have a test for it. When removing the code above, the new test fails with: ptype array_with_buggy_negative_bounds_type^M type = array [240..244] of signed_byte^M (gdb) FAIL: gdb.dwarf2/subrange.exp: ptype array_with_buggy_negative_bounds_type instead of the expected: ptype array_with_buggy_negative_bounds_type^M type = array [-16..-12] of signed_byte^M (gdb) PASS: gdb.dwarf2/subrange.exp: ptype array_with_buggy_negative_bounds_type [1] https://gitlab.com/gnutools/binutils-gdb/-/blob/5ea14aa4e53fa37f4ba4517497ed2c1e4c60dee2/gdb/dwarf2/read.c#L17681-17695 Change-Id: I1992a3ff0cb1e90fa8a9114dae6c591792f059c2 Diff: --- gdb/testsuite/gdb.dwarf2/subrange.exp | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/gdb/testsuite/gdb.dwarf2/subrange.exp b/gdb/testsuite/gdb.dwarf2/subrange.exp index 72d7babc88e..97743ee1099 100644 --- a/gdb/testsuite/gdb.dwarf2/subrange.exp +++ b/gdb/testsuite/gdb.dwarf2/subrange.exp @@ -28,6 +28,7 @@ Dwarf::assemble $asm_file { compile_unit {{language @DW_LANG_Pascal83}} { declare_labels byte_label typedef_label array_label + # A subrange's underlying type that is a typedef. byte_label: base_type { {name byte} {encoding @DW_ATE_unsigned} @@ -54,6 +55,28 @@ Dwarf::assemble $asm_file { {name TByteArray} {type :$array_label} } + + # This subrange's underlying type is signed, but the bounds are + # specified using a non-signed form. + declare_labels signed_byte_label subrange_with_buggy_negative_bounds_label + + signed_byte_label: base_type { + {name signed_byte} + {encoding @DW_ATE_signed} + {byte_size 1 DW_FORM_sdata} + } + + # The bounds mean -16 to -12. + subrange_with_buggy_negative_bounds_label: subrange_type { + {lower_bound 0xf0 DW_FORM_udata} + {upper_bound 0xf4 DW_FORM_udata} + {type :$signed_byte_label} + } + + DW_TAG_variable { + {name subrange_with_buggy_negative_bounds_variable} + {type :$subrange_with_buggy_negative_bounds_label} + } } } } @@ -67,3 +90,5 @@ gdb_test_no_output "set language pascal" gdb_test "ptype TByteArray" \ "type = array \\\[0\\.\\.191\\\] of byte" +gdb_test "ptype subrange_with_buggy_negative_bounds_variable" \ + "type = -16\\.\\.-12"
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