diff options
Diffstat (limited to 'gcc/libgcc2.c')
| -rw-r--r-- | gcc/libgcc2.c | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/gcc/libgcc2.c b/gcc/libgcc2.c index 34b4cccc52f..9e7aa99ae94 100644 --- a/gcc/libgcc2.c +++ b/gcc/libgcc2.c @@ -3886,9 +3886,9 @@ next_stack_level (void *pc, frame_state *udata, frame_state *caller_udata, return 0; /* Now go back to our caller's stack frame. If our caller's CFA was - saved in a register in this stack frame or a previous one, - restore it; otherwise, assume CFA register was saved in SP and - restore it to our CFA value. */ + saved in a register in this stack frame or a previous one, restore it; + otherwise, assume CFA register is SP and restore it to our CFA value + (which is defined to be the value of SP in the caller's frame). */ p = saved_regs->reg[caller_udata->cfa_reg]; if (p) @@ -4107,7 +4107,12 @@ label: On the SPARC, this means flushing the register windows. */ __builtin_unwind_init (); - /* Now reset pc to the right throw point. */ + /* Now reset pc to the right throw point. The return address points to + the instruction after the call to __throw; we subtract 1 so that pc + points into the call insn itself. Since we work with PC ranges (as + opposed to specific call sites), it isn't important for it to point to + the very beginning of the call insn, and making it do so would be + hard on targets with variable length call insns. */ pc = __builtin_extract_return_addr (__builtin_return_address (0)) - 1; handler = throw_helper (eh, pc, my_udata, &offset); @@ -4157,7 +4162,12 @@ label: On the SPARC, this means flushing the register windows. */ __builtin_unwind_init (); - /* Now reset pc to the right throw point. */ + /* Now reset pc to the right throw point. The return address points to + the instruction after the call to __throw; we subtract 1 so that pc + points into the call insn itself. Since we work with PC ranges (as + opposed to specific call sites), it isn't important for it to point to + the very beginning of the call insn, and making it do so would be + hard on targets with variable length call insns. */ pc = __builtin_extract_return_addr (__builtin_return_address (0)) - 1; handler = throw_helper (eh, pc, my_udata, &offset); |