[PATCHv2] gdb/fortran: Use floatformats_ia64_quad for fortran 16-byte floats

Andrew Burgess
2019-05-16T16:01:04Z

This new version moves the use of floatformats_ia64_quad out of
f-lang.c, which I think is an improvement. With this done I plan to
push this patch shortly unless anyone complains.

Thanks,
Andrew

---

PR gdb/18644 is caused by GDB using the wrong floating point format
for gfortran's 16-byte floating point type, including when the 16-byte
float is used as the component of a 32-byte complex type.

This commit addresses the issue in two places, first in i386-tdep.c,
there is already some code to force the use of floatformats_ia64_quad
for specific named types, this is extended to include the type names
that gfortran uses for its 16-byte floats.

Second, the builtin 16-byte float type (in f-lang.c) is changed so it
no longer uses gdbarch_long_double_format. On i386 this type is not
16-bytes, but is smaller, this is not what gfortran is expecting.
Instead we now use gdbarch_floatformat_for_type and ask for a
16-byte (128 bit) type using the common gfortran type name. This is
then spotted in i386-tdep.c (thanks to the first change above) and we
again get floatformats_ia64_quad returned.

This patch was tested on X86-64/GNU-Linux using '--target_board=unix'
and '--target_board=unix/-m32', and resolves all of the known failures
associated with PR gdb/18644. I've also added the test case from the
original bug report.

gdb/ChangeLog:

PR gdb/18644:
* f-lang.c (build_fortran_types): Use floatformats_ia64_quad for
16-byte floats.
* i386-tdep.c (i386_floatformat_for_type): Use
floatformats_ia64_quad for the 16-byte floating point component
within a fortran 32-byte complex number.

gdb/testsuite/ChangeLog:

PR gdb/18644
* gdb.fortran/complex.exp: Remove setup_kfail calls.
* gdb.fortran/printing-types.exp: Add new test.
* gdb.fortran/printing-types.f90: Add 16-byte real variable for
testing.
* gdb.fortran/type-kinds.exp (test_cast_1_to_type_kind): Remove
setup_kfail call.
---
gdb/ChangeLog | 9 +++++++++
gdb/f-lang.c | 4 ++--
gdb/i386-tdep.c | 4 +++-
gdb/testsuite/ChangeLog | 10 ++++++++++
gdb/testsuite/gdb.fortran/complex.exp | 2 --
gdb/testsuite/gdb.fortran/printing-types.exp | 1 +
gdb/testsuite/gdb.fortran/printing-types.f90 | 2 ++
gdb/testsuite/gdb.fortran/type-kinds.exp | 6 ------
8 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/gdb/f-lang.c b/gdb/f-lang.c
index 9da6fdb3e1c..5855c68b38c 100644
--- a/gdb/f-lang.c
+++ b/gdb/f-lang.c
@@ -727,9 +727,9 @@ build_fortran_types (struct gdbarch *gdbarch)
builtin_f_type->builtin_real_s8
= arch_float_type (gdbarch, gdbarch_double_bit (gdbarch),
"real*8", gdbarch_double_format (gdbarch));
+ auto fmt = gdbarch_floatformat_for_type (gdbarch, "real(kind=16)", 128);
builtin_f_type->builtin_real_s16
- = arch_float_type (gdbarch, gdbarch_long_double_bit (gdbarch),
- "real*16", gdbarch_long_double_format (gdbarch));
+ = arch_float_type (gdbarch, 128, "real*16", fmt);

builtin_f_type->builtin_complex_s8
= arch_complex_type (gdbarch, "complex*8",
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index 54d9dd873b8..66fc6d679e2 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -8158,7 +8158,9 @@ i386_floatformat_for_type (struct gdbarch *gdbarch,
if (len == 128 && name)
if (strcmp (name, "__float128") == 0
|| strcmp (name, "_Float128") == 0
- || strcmp (name, "complex _Float128") == 0)
+ || strcmp (name, "complex _Float128") == 0
+ || strcmp (name, "complex(kind=16)") == 0
+ || strcmp (name, "real(kind=16)") == 0)
return floatformats_ia64_quad;

return default_floatformat_for_type (gdbarch, name, len);
diff --git a/gdb/testsuite/gdb.fortran/complex.exp b/gdb/testsuite/gdb.fortran/complex.exp
index 136f1c4df79..94ac53afc70 100644
--- a/gdb/testsuite/gdb.fortran/complex.exp
+++ b/gdb/testsuite/gdb.fortran/complex.exp
@@ -33,7 +33,6 @@ gdb_test "print c4" " = \\(1000,-50\\)"
gdb_test "print c8" " = \\(321,-22\\)"
gdb_test "print dc" " = \\(321,-22\\)"

-setup_kfail gdb/18644 "*-*-*"
gdb_test "print c16" " = \\(-874,19\\)"

gdb_test "whatis c" "type = complex\\(kind=4\\)"
@@ -53,7 +52,6 @@ gdb_test "print \$_creal (dc)" " = 321"
gdb_test "whatis \$" " = real\\*8"

gdb_test "whatis c16" "type = complex\\(kind=16\\)"
-setup_kfail gdb/18644 "*-*-*"
gdb_test "print \$_creal (c16)" " = -874"
gdb_test "whatis \$" " = real\\*16"

diff --git a/gdb/testsuite/gdb.fortran/printing-types.exp b/gdb/testsuite/gdb.fortran/printing-types.exp
index 2f6be4ec249..6394e45f4c3 100644
--- a/gdb/testsuite/gdb.fortran/printing-types.exp
+++ b/gdb/testsuite/gdb.fortran/printing-types.exp
@@ -33,3 +33,4 @@ gdb_test "print oneByte" " = 1"
gdb_test "print twobytes" " = 2"
gdb_test "print chvalue" " = \'a\'"
gdb_test "print logvalue" " = \.TRUE\."
+gdb_test "print rVal" " = 2000"
diff --git a/gdb/testsuite/gdb.fortran/printing-types.f90 b/gdb/testsuite/gdb.fortran/printing-types.f90
index b4ff928604f..36b63532c8e 100644
--- a/gdb/testsuite/gdb.fortran/printing-types.f90
+++ b/gdb/testsuite/gdb.fortran/printing-types.f90
@@ -18,10 +18,12 @@ program prog
integer(2) :: twoBytes
character :: chValue
logical(1) :: logValue
+ real(kind=16) :: rVal

oneByte = 1
twoBytes = 2
chValue = 'a'
logValue = .true.
+ rVal = 2000
write(*,*) s
end
diff --git a/gdb/testsuite/gdb.fortran/type-kinds.exp b/gdb/testsuite/gdb.fortran/type-kinds.exp
index 1ae15b96f1a..9d19a9ceb39 100644
--- a/gdb/testsuite/gdb.fortran/type-kinds.exp
+++ b/gdb/testsuite/gdb.fortran/type-kinds.exp
@@ -27,12 +27,6 @@ if { [skip_fortran_tests] } { continue }
proc test_cast_1_to_type_kind {base_type type_kind cast_result size_result} {
set type_string "$base_type (kind=$type_kind)"
gdb_test "p (($type_string) 1)" " = $cast_result"
-
- if {($base_type == "real" || $base_type == "complex")
- && $type_kind == 16} {
- setup_kfail gdb/18644 "*-*-*"
- }
-
gdb_test "p sizeof (($type_string) 1)" " = $size_result"
}

--
2.14.5