gdb/riscv: Don't error when decoding a 6 or 8 byte instruction
If the RISC-V prologue scanner finds a 6 or 8 byte instruction we currently throw an internal error, which is not great for the user. A mechanism already exists in the prologue scanner to leave instructions marked as unknown so that we can stop the prologue scan without raising an error, this is used for all 2 and 4 byte instructions that are not part of the small set the prologue scanner actually understands. This commit changes GDB so that all 6 and 8 byte instructions are marked as unknown, rather than causing an error. gdb/ChangeLog: * riscv-tdep.c (riscv_insn::decode): Gracefully ignore instructions of lengths 6 or 8 bytes. gdb/testsuite/ChangeLog: * gdb.arch/riscv-unwind-long-insn-6.s: New file. * gdb.arch/riscv-unwind-long-insn-8.s: New file. * gdb.arch/riscv-unwind-long-insn.c: New file. * gdb.arch/riscv-unwind-long-insn.exp: New file.
This commit is contained in:
Andrew Burgess
parent
fbe4d6650d
commit
312617a3d0
7 changed files with 194 additions and 4 deletions
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@ -1,3 +1,8 @@
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2019-06-05 Andrew Burgess <andrew.burgess@embecosm.com>
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* riscv-tdep.c (riscv_insn::decode): Gracefully ignore
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instructions of lengths 6 or 8 bytes.
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2019-06-04 Pedro Alves <palves@redhat.com>
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* common/gdb_unique_ptr.h (make_unique_xstrdup): New.
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@ -1385,10 +1385,12 @@ riscv_insn::decode (struct gdbarch *gdbarch, CORE_ADDR pc)
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m_opcode = OTHER;
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}
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else
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internal_error (__FILE__, __LINE__,
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_("unable to decode %d byte instructions in "
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"prologue at %s"), m_length,
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core_addr_to_string (pc));
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{
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/* This must be a 6 or 8 byte instruction, we don't currently decode
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any of these, so just ignore it. */
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gdb_assert (m_length == 6 || m_length == 8);
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m_opcode = OTHER;
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}
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}
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/* The prologue scanner. This is currently only used for skipping the
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@ -1,3 +1,10 @@
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2019-06-05 Andrew Burgess <andrew.burgess@embecosm.com>
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* gdb.arch/riscv-unwind-long-insn-6.s: New file.
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* gdb.arch/riscv-unwind-long-insn-8.s: New file.
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* gdb.arch/riscv-unwind-long-insn.c: New file.
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* gdb.arch/riscv-unwind-long-insn.exp: New file.
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2019-06-04 Christian Biesinger <cbiesinger@google.com>
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* gdb.python/py-type.exp: Test for new gdb.Type.objfile property.
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45
gdb/testsuite/gdb.arch/riscv-unwind-long-insn-6.s
Normal file
45
gdb/testsuite/gdb.arch/riscv-unwind-long-insn-6.s
Normal file
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@ -0,0 +1,45 @@
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/* Copyright 2019 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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.option nopic
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.text
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.align 1
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.globl bar
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.type bar, @function
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bar:
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tail 1f
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.size bar, .-func
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.align 1
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.globl func
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.type func, @function
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func:
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/* A fake 6 byte instruction. This is never executed, but the
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prologue scanner will try to decode it. These long
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instructions are ISA extensions, I use .byte rather than an
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actual instruction mnemonic so that the test can be compiled
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with a toolchain that doesn't include any long instruction
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extensions. */
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.byte 0x1f, 0x00, 0x00, 0x00, 0x00, 0x00
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1:
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addi sp,sp,-16
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sw s0,12(sp)
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addi s0,sp,16
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nop
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lw s0,12(sp)
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addi sp,sp,16
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jr ra
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.size func, .-func
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45
gdb/testsuite/gdb.arch/riscv-unwind-long-insn-8.s
Normal file
45
gdb/testsuite/gdb.arch/riscv-unwind-long-insn-8.s
Normal file
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@ -0,0 +1,45 @@
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/* Copyright 2019 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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.option nopic
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.text
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.align 1
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.globl bar
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.type bar, @function
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bar:
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tail 1f
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.size bar, .-func
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.align 1
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.globl func
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.type func, @function
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func:
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/* A fake 8 byte instruction. This is never executed, but the
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prologue scanner will try to decode it. These long
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instructions are ISA extensions, I use .byte rather than an
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actual instruction mnemonic so that the test can be compiled
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with a toolchain that doesn't include any long instruction
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extensions. */
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.byte 0x3f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
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1:
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addi sp,sp,-16
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sw s0,12(sp)
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addi s0,sp,16
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nop
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lw s0,12(sp)
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addi sp,sp,16
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jr ra
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.size func, .-func
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25
gdb/testsuite/gdb.arch/riscv-unwind-long-insn.c
Normal file
25
gdb/testsuite/gdb.arch/riscv-unwind-long-insn.c
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@ -0,0 +1,25 @@
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/* Copyright 2019 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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extern void func (void);
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extern void bar (void);
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int
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main ()
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{
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bar ();
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func ();
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return 0;
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}
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61
gdb/testsuite/gdb.arch/riscv-unwind-long-insn.exp
Normal file
61
gdb/testsuite/gdb.arch/riscv-unwind-long-insn.exp
Normal file
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@ -0,0 +1,61 @@
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# Copyright 2019 Free Software Foundation, Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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# This tests GDB's ability to handle 6 and 8 byte instructions in the
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# RISC-V prologue scanner. These instruction should be ignored, but
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# should not result in an error that interrupts the debug session.
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#
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# Each of the files riscv-unwind-long-insn-*.s include a function
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# (func) that contains a fake long instruction (6 or 8 bytes) in the
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# prologue. We trick GDB into parsing the fake instruction by tail
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# calling from a different function, 'bar' to the middle of 'func'.
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if {![istarget "riscv*-*-*"]} {
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verbose "Skipping ${gdb_test_file_name}."
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return
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}
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foreach_with_prefix {insn_size} {6 8} {
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standard_testfile riscv-unwind-long-insn.c \
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riscv-unwind-long-insn-${insn_size}.s
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set testfile "${testfile}-${insn_size}"
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if {[prepare_for_testing "failed to prepare" $testfile \
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"$srcfile $srcfile2" debug]} {
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return -1
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}
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if ![runto_main] then {
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fail "can't run to main"
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return 0
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}
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gdb_breakpoint "bar"
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gdb_continue_to_breakpoint "bar"
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# This next single instruction step takes us through a tail-call
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# from 'bar' into 'func'.
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gdb_test "si" "func \(\).*"
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# Now check that we have a sane backtrace.
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gdb_test "bt" \
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[multi_line \
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"#0\[ \t\]*func \\\(\\\) at .*$srcfile2:\[0-9\]+" \
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"#1\[ \t\]*$hex in main \\\(\\\) at .*$srcfile:\[0-9\]+"] \
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"Backtrace to the main frame"
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# Finally finish, and we should end up back in main.
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gdb_test "finish" "main \\\(\\\) at .*$srcfile:.*"
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}
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