diff options
Diffstat (limited to 'gcc/unwind-dw2.c')
| -rw-r--r-- | gcc/unwind-dw2.c | 28 |
1 files changed, 21 insertions, 7 deletions
diff --git a/gcc/unwind-dw2.c b/gcc/unwind-dw2.c index 7596ef0..5a26d0b 100644 --- a/gcc/unwind-dw2.c +++ b/gcc/unwind-dw2.c @@ -1089,11 +1089,17 @@ uw_update_context_1 (struct _Unwind_Context *context, _Unwind_FrameState *fs) In very special situations (such as unwind info for signal return), there may be location expressions that use the stack pointer as well. - Given that other unwind mechanisms generally won't work if you try - to represent stack pointer saves and restores directly, we don't - bother conditionalizing this at all. */ - tmp_sp = (_Unwind_Ptr) context->cfa; - _Unwind_SetGRPtr (&orig_context, __builtin_dwarf_sp_column (), &tmp_sp); + Do this conditionally for one frame. This allows the unwind info + for one frame to save a copy of the stack pointer from the previous + frame, and be able to use much easier CFA mechanisms to do it. + Always zap the saved stack pointer value for the next frame; carrying + the value over from one frame to another doesn't make sense. */ + if (!_Unwind_GetGRPtr (&orig_context, __builtin_dwarf_sp_column ())) + { + tmp_sp = (_Unwind_Ptr) context->cfa; + _Unwind_SetGRPtr (&orig_context, __builtin_dwarf_sp_column (), &tmp_sp); + } + _Unwind_SetGRPtr (context, __builtin_dwarf_sp_column (), NULL); /* Compute this frame's CFA. */ switch (fs->cfa_how) @@ -1234,6 +1240,7 @@ uw_install_context_1 (struct _Unwind_Context *current, struct _Unwind_Context *target) { long i; + void *target_cfa; #if __GTHREADS { @@ -1256,11 +1263,18 @@ uw_install_context_1 (struct _Unwind_Context *current, memcpy (c, t, dwarf_reg_size_table[i]); } + /* If the last frame records a saved stack pointer, use it. */ + if (_Unwind_GetGRPtr (target, __builtin_dwarf_sp_column ())) + target_cfa = (void *)(_Unwind_Ptr) + _Unwind_GetGR (target, __builtin_dwarf_sp_column ()); + else + target_cfa = target->cfa; + /* We adjust SP by the difference between CURRENT and TARGET's CFA. */ if (STACK_GROWS_DOWNWARD) - return target->cfa - current->cfa + target->args_size; + return target_cfa - current->cfa + target->args_size; else - return current->cfa - target->cfa - target->args_size; + return current->cfa - target_cfa - target->args_size; } static inline _Unwind_Ptr |