[PATCH v2 5/7] Implement complex arithmetic

Tom Tromey
2020-03-20T21:53:43Z

This adds support for complex arithmetic to gdb. Now something like
"print 23 + 7i" will work.

Addition, subtraction, multiplication, division, and equality testing
are supported binary operations.

Unary +, negation, and complement are supported. Following GCC, the ~
operator computes the complex conjugate.

gdb/ChangeLog
2020-03-20 Tom Tromey <tom@tromey.com>

PR exp/25299:
* valarith.c (promotion_type, complex_binop): New functions.
(scalar_binop): Handle complex numbers. Use promotion_type.
(value_pos, value_neg, value_complement): Handle complex numbers.

gdb/testsuite/ChangeLog
2020-03-20 Tom Tromey <tom@tromey.com>

* gdb.base/complex-parts.exp: Add arithmetic tests.
---
gdb/ChangeLog | 7 +
gdb/testsuite/ChangeLog | 4 +
gdb/testsuite/gdb.base/complex-parts.exp | 26 +++
gdb/valarith.c | 199 ++++++++++++++++++++---
4 files changed, 215 insertions(+), 21 deletions(-)

diff --git a/gdb/testsuite/gdb.base/complex-parts.exp b/gdb/testsuite/gdb.base/complex-parts.exp
index 071de5c56d7..0cf4abf56ec 100644
--- a/gdb/testsuite/gdb.base/complex-parts.exp
+++ b/gdb/testsuite/gdb.base/complex-parts.exp
@@ -60,3 +60,29 @@ gdb_test "p \$_cimag (i1)" "expected a complex number"
gdb_test "p \$_creal (d1)" "expected a complex number"
gdb_test "p \$_creal (f1)" "expected a complex number"
gdb_test "p \$_creal (i1)" "expected a complex number"
+
+#
+# General complex number tests.
+#
+
+gdb_test "print 23 + 7i" " = 23 \\+ 7i"
+gdb_test "print 23.125f + 7i" " = 23.125 \\+ 7i"
+gdb_test "print 23 + 7.25fi" " = 23 \\+ 7.25i"
+gdb_test "print (23 + 7i) + (17 + 10i)" " = 40 \\+ 17i"
+gdb_test "print 23 + -7i" " = 23 \\+ -7i"
+gdb_test "print 23 - 7i" " = 23 \\+ -7i"
+
+gdb_test "print -(23 + 7i)" " = -23 \\+ -7i"
+gdb_test "print +(23 + 7i)" " = 23 \\+ 7i"
+gdb_test "print ~(23 + 7i)" " = 23 \\+ -7i"
+
+gdb_test "print (5 + 5i) * (2 + 2i)" " = 0 \\+ 20i"
+
+gdb_test "print (5 + 7i) == (5 + 7i)" " = 1"
+gdb_test "print (5 + 7i) == (8 + 7i)" " = 0"
+gdb_test "print (5 + 7i) == (5 + 92i)" " = 0"
+gdb_test "print (5 + 7i) != (5 + 7i)" " = 0"
+gdb_test "print (5 + 7i) != (8 + 7i)" " = 1"
+gdb_test "print (5 + 7i) != (5 + 92i)" " = 1"
+
+gdb_test "print (20 - 4i) / (3 + 2i)" " = 4 \\+ -4i"
diff --git a/gdb/valarith.c b/gdb/valarith.c
index be0e0731bee..07cb5014bb2 100644
--- a/gdb/valarith.c
+++ b/gdb/valarith.c
@@ -911,6 +911,157 @@ value_args_as_target_float (struct value *arg1, struct value *arg2,
TYPE_NAME (type2));
}

+/* A helper function that finds the type to use for a binary operation
+ involving TYPE1 and TYPE2. */
+
+static struct type *
+promotion_type (struct type *type1, struct type *type2)
+{
+ struct type *result_type;
+
+ if (is_floating_type (type1) || is_floating_type (type2))
+ {
+ /* If only one type is floating-point, use its type.
+ Otherwise use the bigger type. */
+ if (!is_floating_type (type1))
+ result_type = type2;
+ else if (!is_floating_type (type2))
+ result_type = type1;
+ else if (TYPE_LENGTH (type2) > TYPE_LENGTH (type1))
+ result_type = type2;
+ else
+ result_type = type1;
+ }
+ else
+ {
+ /* Integer types. */
+ if (TYPE_LENGTH (type1) > TYPE_LENGTH (type2))
+ result_type = type1;
+ else if (TYPE_LENGTH (type2) > TYPE_LENGTH (type1))
+ result_type = type2;
+ else if (TYPE_UNSIGNED (type1))
+ result_type = type1;
+ else if (TYPE_UNSIGNED (type2))
+ result_type = type2;
+ else
+ result_type = type1;
+ }
+
+ return result_type;
+}
+
+static struct value *scalar_binop (struct value *arg1, struct value *arg2,
+ enum exp_opcode op);
+
+/* Perform a binary operation on complex operands. */
+
+static struct value *
+complex_binop (struct value *arg1, struct value *arg2, enum exp_opcode op)
+{
+ struct type *arg1_type = check_typedef (value_type (arg1));
+ struct type *arg2_type = check_typedef (value_type (arg2));
+
+ struct value *arg1_real, *arg1_imag, *arg2_real, *arg2_imag;
+ if (TYPE_CODE (arg1_type) == TYPE_CODE_COMPLEX)
+ {
+ arg1_real = value_real_part (arg1);
+ arg1_imag = value_imaginary_part (arg1);
+ }
+ else
+ {
+ arg1_real = arg1;
+ arg1_imag = value_zero (arg1_type, not_lval);
+ }
+ if (TYPE_CODE (arg2_type) == TYPE_CODE_COMPLEX)
+ {
+ arg2_real = value_real_part (arg2);
+ arg2_imag = value_imaginary_part (arg2);
+ }
+ else
+ {
+ arg2_real = arg2;
+ arg2_imag = value_zero (arg2_type, not_lval);
+ }
+
+ struct type *comp_type = promotion_type (value_type (arg1_real),
+ value_type (arg2_real));
+ arg1_real = value_cast (comp_type, arg1_real);
+ arg1_imag = value_cast (comp_type, arg1_imag);
+ arg2_real = value_cast (comp_type, arg2_real);
+ arg2_imag = value_cast (comp_type, arg2_imag);
+
+ struct type *result_type = init_complex_type (nullptr, comp_type);
+
+ struct value *result_real, *result_imag;
+ switch (op)
+ {
+ case BINOP_ADD:
+ case BINOP_SUB:
+ result_real = scalar_binop (arg1_real, arg2_real, op);
+ result_imag = scalar_binop (arg1_imag, arg2_imag, op);
+ break;
+
+ case BINOP_MUL:
+ {
+ struct value *x1 = scalar_binop (arg1_real, arg2_real, op);
+ struct value *x2 = scalar_binop (arg1_imag, arg2_imag, op);
+ result_real = scalar_binop (x1, x2, BINOP_SUB);
+
+ x1 = scalar_binop (arg1_real, arg2_imag, op);
+ x2 = scalar_binop (arg1_imag, arg2_real, op);
+ result_imag = scalar_binop (x1, x2, BINOP_ADD);
+ }
+ break;
+
+ case BINOP_DIV:
+ {
+ if (TYPE_CODE (arg2_type) == TYPE_CODE_COMPLEX)
+ {
+ struct value *conjugate = value_complement (arg2);
+ /* We have to reconstruct ARG1, in case the type was
+ promoted. */
+ arg1 = value_literal_complex (arg1_real, arg1_imag, result_type);
+
+ struct value *numerator = scalar_binop (arg1, conjugate,
+ BINOP_MUL);
+ arg1_real = value_real_part (numerator);
+ arg1_imag = value_imaginary_part (numerator);
+
+ struct value *x1 = scalar_binop (arg2_real, arg2_real, BINOP_MUL);
+ struct value *x2 = scalar_binop (arg2_imag, arg2_imag, BINOP_MUL);
+ arg2_real = scalar_binop (x1, x2, BINOP_ADD);
+ }
+
+ result_real = scalar_binop (arg1_real, arg2_real, op);
+ result_imag = scalar_binop (arg1_imag, arg2_real, op);
+ }
+ break;
+
+ case BINOP_EQUAL:
+ case BINOP_NOTEQUAL:
+ {
+ struct value *x1 = scalar_binop (arg1_real, arg2_real, op);
+ struct value *x2 = scalar_binop (arg1_imag, arg2_imag, op);
+
+ LONGEST v1 = value_as_long (x1);
+ LONGEST v2 = value_as_long (x2);
+
+ if (op == BINOP_EQUAL)
+ v1 = v1 && v2;
+ else
+ v1 = v1 || v2;
+
+ return value_from_longest (value_type (x1), v1);
+ }
+ break;
+
+ default:
+ error (_("Invalid binary operation on numbers."));
+ }
+
+ return value_literal_complex (result_real, result_imag, result_type);
+}
+
/* Perform a binary operation on two operands which have reasonable
representations as integers or floats. This includes booleans,
characters, integers, or floats.
@@ -929,23 +1080,17 @@ scalar_binop (struct value *arg1, struct value *arg2, enum exp_opcode op)
type1 = check_typedef (value_type (arg1));
type2 = check_typedef (value_type (arg2));

+ if (TYPE_CODE (type1) == TYPE_CODE_COMPLEX
+ || TYPE_CODE (type2) == TYPE_CODE_COMPLEX)
+ return complex_binop (arg1, arg2, op);
+
if ((!is_floating_value (arg1) && !is_integral_type (type1))
|| (!is_floating_value (arg2) && !is_integral_type (type2)))
error (_("Argument to arithmetic operation not a number or boolean."));

if (is_floating_type (type1) || is_floating_type (type2))
{
- /* If only one type is floating-point, use its type.
- Otherwise use the bigger type. */
- if (!is_floating_type (type1))
- result_type = type2;
- else if (!is_floating_type (type2))
- result_type = type1;
- else if (TYPE_LENGTH (type2) > TYPE_LENGTH (type1))
- result_type = type2;
- else
- result_type = type1;
-
+ result_type = promotion_type (type1, type2);
val = allocate_value (result_type);

struct type *eff_type_v1, *eff_type_v2;
@@ -1013,16 +1158,8 @@ scalar_binop (struct value *arg1, struct value *arg2, enum exp_opcode op)
if one of the operands is unsigned. */
if (op == BINOP_RSH || op == BINOP_LSH || op == BINOP_EXP)
result_type = type1;
- else if (TYPE_LENGTH (type1) > TYPE_LENGTH (type2))
- result_type = type1;
- else if (TYPE_LENGTH (type2) > TYPE_LENGTH (type1))
- result_type = type2;
- else if (TYPE_UNSIGNED (type1))
- result_type = type1;
- else if (TYPE_UNSIGNED (type2))
- result_type = type2;
else
- result_type = type1;
+ result_type = promotion_type (type1, type2);

if (TYPE_UNSIGNED (result_type))
{
@@ -1629,7 +1766,8 @@ value_pos (struct value *arg1)
type = check_typedef (value_type (arg1));

if (is_integral_type (type) || is_floating_value (arg1)
- || (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type)))
+ || (TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type))
+ || TYPE_CODE (type) == TYPE_CODE_COMPLEX)
return value_from_contents (type, value_contents (arg1));
else
error (_("Argument to positive operation not a number."));
@@ -1663,6 +1801,15 @@ value_neg (struct value *arg1)
}
return val;
}
+ else if (TYPE_CODE (type) == TYPE_CODE_COMPLEX)
+ {
+ struct value *real = value_real_part (arg1);
+ struct value *imag = value_imaginary_part (arg1);
+
+ real = value_neg (real);
+ imag = value_neg (imag);
+ return value_literal_complex (real, imag, type);
+ }
else
error (_("Argument to negate operation not a number."));
}
@@ -1696,6 +1843,16 @@ value_complement (struct value *arg1)
value_contents_all (tmp), TYPE_LENGTH (eltype));
}
}
+ else if (TYPE_CODE (type) == TYPE_CODE_COMPLEX)
+ {
+ /* GCC has an extension that treats ~complex as the complex
+ conjugate. */
+ struct value *real = value_real_part (arg1);
+ struct value *imag = value_imaginary_part (arg1);
+
+ imag = value_neg (imag);
+ return value_literal_complex (real, imag, type);
+ }
else
error (_("Argument to complement operation not an integer, boolean."));

--
2.17.2