[PATCH] gdb/testsuite: Fix gdb.rocm/displaced-stepping.exp

[Lancelot SIX <lancelot.six@amd.com>]

The gdb.rocm/displaced-stepping.exp testcase currently fails with:

  with debug displaced on -- stepi
  Unhandled dwarf expression opcode 0xe9
  (gdb) FAIL: gdb.rocm/displaced-stepping.exp: with debug displaced on -- stepi

This is because when doing the stepi, GDB computes the current frame ID
in set_step_info.  This will go and evaluate the CFA for the current
frame, which reads AMDGPU debug info, which is not supported by GDB
currently.

Current AMDGPU DWARF requires changes expected to be available in the
future DWARF-6 standard (address space support), as well as llvm private
opcodes (DW_OP_LLVM_user DW_OP_LLVM_form_aspace_address):

    $ llvm-dwarfdump --debug-frame displaced-stepping.0.hip-amdgcn-amd-amdhsa--gfx1031
    [...]
    00000014 00000018 00000018 FDE cie=00000000 pc=00001a00...00001b64
      Format:       DWARF32
      DW_CFA_def_cfa_expression: DW_OP_lit0, DW_OP_lit6, DW_OP_LLVM_user DW_OP_LLVM_form_aspace_address

At this point, there is no way to support this in GDB, so instead this
patch proposes to fix the failure by instructing the compiler to not
produce any unwind table.

Tested on x86_64-linux + AMDGPU-gfx1031.

Change-Id: I2e62270f39c9e96324ae01d401bafb46cfff596c
---
 gdb/testsuite/gdb.rocm/displaced-stepping.exp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gdb/testsuite/gdb.rocm/displaced-stepping.exp b/gdb/testsuite/gdb.rocm/displaced-stepping.exp
index 2466a678f19..a72c19e5314 100644
--- a/gdb/testsuite/gdb.rocm/displaced-stepping.exp
+++ b/gdb/testsuite/gdb.rocm/displaced-stepping.exp
@@ -23,7 +23,8 @@ require allow_hip_tests
 
 # Since GDB doesn't yet understand DWARF expressions generated by the HIP
 # compiler, purposefully generate the binary without debug info.
-if {[build_executable "failed to prepare" $testfile $srcfile {hip}]} {
+if {[build_executable "failed to prepare" $testfile $srcfile \
+	{hip "additional_flags=-fno-unwind-tables -fno-asynchronous-unwind-tables"}]} {
     return
 }
 

base-commit: cfd8ea4e101d9793895d9b8b016da5c2ec6a672a
-- 
2.43.0