On Wed, Jan 4, 2012 at 7:20 PM, Aldy Hernandez <aldy...@gmail.com> wrote: > I fixed this PR, and then it got reopened because the testcase triggered a > different problem on Alpha, Mips, and other architectures. The problem is > actually totally different than the previous fix for 51472, and has nothing > to do with --param tm-max-aggregate-size. > > This problem here is that a load is transformed into a transactional memmove > in such a way that the subsequent SSA uses are pointing to the wrong thing. > For example, originally we have: > > global_var_ssa_999 = global_var; > *p = global_var_ssa_999; > > Through expand_assign_tm -> gimplify_addr -> force_gimple_operand_gsi, the > above gets transformed into this: > > D.1234 = global_var_ssa_999; <-- BOO HISS! Uninitialized. > __builtin__ITM_memmoveRtWt (&D.1234, &global_var, 16); > *p = global_var_ssa_999; <-- Wuuuut? > > We should either propagate D.1234 to the uses of global_var_ssa_999, or copy > D.1234 into global_var_ssa_999 and happily proceed. > Option B is pretty straightforward, and with the attached patch we end up > with: > > __builtin__ITM_memmoveRtWt (&D.1234, &global_var, 16); > global_var_ssa_999 = D.1234; > > The attached patch fixes the ICE on alpha-linux-gnu as tested with a > cross-cc1 build. Fully bootregtested on x86-64 Linux. > > OK?
You want is_gimple_reg () instead of is_gimple_non_addressable () as you can't simply make something addressable at this point. is_gimple_non_addressable looks like a weird redundant predicate to me - it's only used once and its use should be replaced (and the predicate removed). Richard.
