path: root/gdb/testsuite/gdb.base/bitshift.exp

# Copyright 2022 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Test left and right bit shifting, in all languages that have such
# operator.

clean_restart

# Test a print command that prints out RESULT_RE.  If WARNING_OR_ERROR
# is non-empty, it is expected that for languages other than Go, GDB
# prints this warning before the print result.  For Go, this is an
# expected error.  If WARNING_OR_ERROR is empty, it is expected that
# GDB prints no text other than the print result.
proc test_shift {lang cmd result_re {warning_or_error ""}} {
    set cmd_re [string_to_regexp $cmd]

    if {$lang == "go"} {
	if {$warning_or_error != ""} {
	    set error_re "[string_to_regexp $warning_or_error]"
	    gdb_test_multiple $cmd "" {
		-re -wrap "^$cmd_re\r\n$error_re" {
		    pass $gdb_test_name
		}
	    }
	} else {
	    gdb_test_multiple $cmd "" {
		-re -wrap "^$cmd_re\r\n\\$$::decimal$result_re" {
		    pass $gdb_test_name
		}
	    }
	}
    } else {
	if {$warning_or_error != ""} {
	    set warning_re "warning: [string_to_regexp $warning_or_error]\r\n"
	} else {
	    set warning_re ""
	}

	gdb_test_multiple $cmd "" {
	    -re -wrap "^$cmd_re\r\n$warning_re\\$$::decimal$result_re" {
		pass $gdb_test_name
	    }
	}
    }
}

# Some warnings/errors GDB outputs.
set rs_negative_shift_count "right shift count is negative"
set rs_too_large_shift_count "right shift count >= width of type"
set ls_negative_shift_count "left shift count is negative"
set ls_too_large_shift_count "left shift count >= width of type"

# Test a left shift that results in a too-large shift count warning in
# all languages except Go.
proc test_lshift_tl {lang cmd result_re} {
    if {$lang != "go"} {
	test_shift $lang $cmd $result_re $::ls_too_large_shift_count
    } else {
	test_shift $lang $cmd $result_re
    }
}

# Test a right shift that results in a too-large shift count warning
# in all languages except Go.
proc test_rshift_tl {lang cmd result_re} {
    if {$lang != "go"} {
	test_shift $lang $cmd $result_re $::rs_too_large_shift_count
    } else {
	test_shift $lang $cmd $result_re
    }
}

# Return VAL, an integer value converted/cast to the right type for
# LANG.  SIGNED indicates whether the type should be signed or
# unsigned.  BITS indicates the bit width of the type.  E.g., signed=0
# and bits=32 results in:
#   Go            =>  "uint($VAL)"
#   D             =>  "cast(uint) $VAL"
#   Rust          =>  "$VAL as i32"
#   C/C++/others  =>  "(unsigned int) $VAL"
proc make_val_cast {lang signed bits val} {
    if {$lang == "go"} {
	if {$signed} {
	    set sign_prefix ""
	} else {
	    set sign_prefix "u"
	}
	return "${sign_prefix}int${bits}($val)"
    } elseif {$lang == "d"} {
	if {$signed} {
	    set sign_prefix ""
	} else {
	    set sign_prefix "u"
	}
	if {$bits == 8} {
	    set type "byte"
	} elseif {$bits == 16} {
	    set type "short"
	} elseif {$bits == 32} {
	    set type "int"
	} elseif {$bits == 64} {
	    set type "long"
	} else {
	    error "$lang: unsupported bits"
	}
	return "cast(${sign_prefix}$type) $val"
    } elseif {$lang == "rust"} {
	if {$signed} {
	    set sign_prefix "i"
	} else {
	    set sign_prefix "u"
	}
	return "$val as ${sign_prefix}$bits"
    } else {
	# C-like cast.
	if {$signed} {
	    set sign_prefix ""
	} else {
	    set sign_prefix "un"
	}
	if {$bits == 8} {
	    set type "char"
	} elseif {$bits == 16} {
	    set type "short"
	} elseif {$bits == 32} {
	    set type "int"
	} elseif {$bits == 64} {
	    if {$lang == "opencl"} {
		set type "long"
	    } else {
		set type "long long"
	    }
	} else {
	    error "$lang: unsupported bits"
	}
	return "(${sign_prefix}signed $type) $val"
    }
}

# Generate make_int8 ... make_uint64 convenience procs, wrappers
# around make_val_cast.
foreach signed {0 1} {
    if {$signed} {
	set sign_prefix ""
    } else {
	set sign_prefix "u"
    }
    foreach bits {8 16 32 64} {
	proc make_${sign_prefix}int${bits} {lang val} \
	    "make_val_cast \$lang $signed $bits \$val"
    }
}

# Test bitshifting, particularly with negative shift counts and
# too-large-for-type shift counts.  Exercises all C-like-ish
# languages.
proc test_shifts {} {
    global ls_negative_shift_count rs_negative_shift_count

    # Extract the set of all supported languages.  We try all except
    # languages we know wouldn't work.  We do this instead of
    # hardcoding the set of languages that we know work, so that if
    # GDB gains a new language, it is automatically exercised.
    set supported_langs [get_set_option_choices "set language"]

    foreach_with_prefix lang $supported_langs {
	set skip_langs {
	    "unknown" "ada" "modula-2" "pascal" "fortran"
	}
	if {[lsearch -exact $skip_langs $lang] >= 0} {
	    continue
	}

	gdb_test_no_output "set language $lang"

	# Make sure a signed left shift that overflows, i.e., whose
	# result isn't representable in the signed type of the lhs,
	# which is actually undefined, doesn't crash GDB when is it
	# built with UBSan.

	with_test_prefix "lsh overflow" {
	    test_shift $lang "print /x 0x0fffffffffffffff << 8" \
		" = 0xffffffffffffff00"
	    test_shift $lang "print /x 0x0fffffff << 8" \
		" = 0xffffff00"

	    # Make sure the result is still signed when the lhs was
	    # signed.
	    test_shift $lang "print 0x0fffffffffffffff << 8" " = -256"
	    test_shift $lang "print 0x0fffffff << 8" " = -256"
	}

	# 8-bit and 16-bit are promoted to int.
	with_test_prefix "8-bit, promoted" {
	    foreach lhs \
		[list \
		     [make_int8 $lang 0x0f] \
		     [make_uint8 $lang 0x0f]] \
	    {
		test_shift $lang "print /x $lhs << 8" " = 0xf00"
		test_shift $lang "print $lhs << 8" " = 3840"
	    }
	}
	with_test_prefix "16-bit, promoted" {
	    foreach lhs \
		[list \
		     [make_int16 $lang 0x0fff] \
		     [make_uint16 $lang 0x0fff]] \
	    {
		test_shift $lang "print /x $lhs << 8" " = 0xfff00"
		test_shift $lang "print $lhs << 8" " = 1048320"
	    }
	}

	# Similarly, test shifting with both negative and too-large
	# rhs.  Both cases are undefined, but GDB lets them go through
	# anyhow, similarly to how compilers don't error out.  Try
	# both signed and unsigned lhs.

	# 8-bit lhs, signed and unsigned.  These get promoted to
	# 32-bit int.
	with_test_prefix "8-bit, invalid" {
	    foreach lhs \
		[list \
		     [make_int8 $lang 0x7f] \
		     [make_uint8 $lang 0xff]] \
	    {
		test_shift $lang "print $lhs << -1" " = 0" \
		    $ls_negative_shift_count
		test_shift $lang "print $lhs >> -1" " = 0" \
		    $rs_negative_shift_count

		test_shift $lang "print/x $lhs << 8" " = 0x(7|f)f00"
		test_shift $lang "print/x $lhs >> 8" " = 0x0"

		test_lshift_tl $lang "print $lhs << 32" " = 0"
		test_rshift_tl $lang "print $lhs >> 32" " = 0"
		test_lshift_tl $lang "print $lhs << 33" " = 0"
		test_rshift_tl $lang "print $lhs >> 33" " = 0"
	    }
	}

	# 16-bit lhs, signed and unsigned.  These get promoted to 32-bit int.
	with_test_prefix "16-bit, invalid" {
	    foreach {lhs res} \
		[list \
		     [make_int16 $lang 0x7fff] 0x7fff \
		     [make_uint16 $lang 0xffff] 0xffff] \
	    {
		test_shift $lang "print $lhs << -1" " = 0" \
		    $ls_negative_shift_count
		test_shift $lang "print $lhs >> -1" " = 0" \
		    $rs_negative_shift_count

		# Confirm shifting by 0 doesn't warn.
		test_shift $lang "print/x $lhs << 0" " = $res"
		test_shift $lang "print/x $lhs >> 0" " = $res"

		# These don't overflow due to promotion.
		test_shift $lang "print/x $lhs << 16" " = 0x(7|f)fff0000"
		test_shift $lang "print/x $lhs >> 16" " = 0x0"

		test_lshift_tl $lang "print $lhs << 32" " = 0"
		test_rshift_tl $lang "print $lhs >> 32" " = 0"
		test_lshift_tl $lang "print $lhs << 33" " = 0"
		test_rshift_tl $lang "print $lhs >> 33" " = 0"
	    }
	}

	# 32-bit lhs, signed and unsigned.
	with_test_prefix "32-bit, invalid" {
	    foreach {lhs res} \
		[list \
		     [make_int32 $lang 0x7fffffff] 0x7fffffff \
		     [make_uint32 $lang 0xffffffff] 0xffffffff] \
	    {
		test_shift $lang "print $lhs << -1" " = 0" \
		    $ls_negative_shift_count
		test_shift $lang "print $lhs >> -1" " = 0" \
		    $rs_negative_shift_count

		# Confirm shifting by 0 doesn't warn.
		test_shift $lang "print/x $lhs << 0" " = $res"
		test_shift $lang "print/x $lhs >> 0" " = $res"

		test_lshift_tl $lang "print $lhs << 32" " = 0"
		test_rshift_tl $lang "print $lhs >> 32" " = 0"

		test_lshift_tl $lang "print $lhs << 33" " = 0"
		test_rshift_tl $lang "print $lhs >> 33" " = 0"
	    }
	}

	# 64-bit lhs, signed and unsigned.
	with_test_prefix "64-bit, invalid" {
	    foreach {lhs res} \
		[list \
		     [make_int64 $lang 0x7fffffffffffffff] \
		     0x7fffffffffffffff \
		     \
		     [make_uint64 $lang 0xffffffffffffffff] \
		     0xffffffffffffffff] \
	    {
		test_shift $lang "print $lhs << -1" " = 0" \
		    $ls_negative_shift_count
		test_shift $lang "print $lhs >> -1" " = 0" \
		    $rs_negative_shift_count

		# Confirm shifting by 0 doesn't warn.
		test_shift $lang "print/x $lhs << 0" " = $res"
		test_shift $lang "print/x $lhs >> 0" " = $res"

		test_lshift_tl $lang "print $lhs << 64" " = 0"
		test_rshift_tl $lang "print $lhs >> 64" " = 0"

		test_lshift_tl $lang "print $lhs << 65" " = 0"
		test_rshift_tl $lang "print $lhs >> 65" " = 0"
	    }
	}

	# Right shift a negative number by a negative amount.
	with_test_prefix "neg lhs/rhs" {
	    test_shift $lang "print -1 >> -1" " = -1" $rs_negative_shift_count
	    test_shift $lang "print -4 >> -2" " = -1" $rs_negative_shift_count
	}

	# Check right shifting a negative value.  For C++, this is
	# implementation-defined, up until C++20.  In most
	# implementations, this performs an arithmetic right shift, so
	# that the result remains negative.  Currently, GDB does
	# whatever the host's compiler does.  If that turns out wrong
	# for some host/target, then GDB should be taught to ask the
	# target gdbarch what to do.
	with_test_prefix "rsh neg lhs" {
	    test_shift $lang "print -1 >> 0" " = -1"
	    test_shift $lang "print -1 >> 1" " = -1"
	    test_shift $lang "print -8 >> 1" " = -4"
	    test_shift $lang "print [make_int64 $lang -8] >> 1" " = -4"
	}

	# Make sure an unsigned 64-bit value with high bit set isn't
	# confused for a negative shift count in the warning messages.
	with_test_prefix "max-uint64" {
	    test_lshift_tl $lang \
		"print 1 << [make_uint64 $lang 0xffffffffffffffff]" " = 0"
	    test_rshift_tl $lang \
		"print 1 >> [make_uint64 $lang 0xffffffffffffffff]" " = 0"
	    test_lshift_tl $lang \
		"print -1 << [make_uint64 $lang 0xffffffffffffffff]" " = 0"
	    test_rshift_tl $lang \
		"print -1 >> [make_uint64 $lang 0xffffffffffffffff]" " = -1"
	}
    }
}

test_shifts