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From: Andrew Burgess <aburgess@sourceware.org> To: gdb-cvs@sourceware.org Subject: [binutils-gdb] sim/ppc: fix for operator precedence warning from clang Date: Mon, 24 Oct 2022 16:19:57 +0000 (GMT) [thread overview] Message-ID: <20221024162001.A7716385840A@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=e0b3df3b4d77706abf5f077477b2ca227fc4e9d1 commit e0b3df3b4d77706abf5f077477b2ca227fc4e9d1 Author: Andrew Burgess <aburgess@redhat.com> Date: Wed Oct 19 15:12:57 2022 +0100 sim/ppc: fix for operator precedence warning from clang In the ppc simulator, clang was warning about some code like this: busy_ptr->nr_writebacks = 1 + (PPC_ONE_BIT_SET_P(out_vmask)) ? 1 : 2; The warning was: operator '?:' has lower precedence than '+'; '+' will be evaluated first I suspect that this is not the original authors intention. PPC_ONE_BIT_SET_P is going to be 0 or 1, so if we evaluate the '+' first, the condition will always be non-zero, so true. The whole expression could then be simplified to just '1', which doesn't make much sense. I suspect the answer the author was expecting was either 2 or 3. Why they didn't just write: busy_ptr->nr_writebacks = (PPC_ONE_BIT_SET_P(out_vmask)) ? 2 : 3; I have no clue, however, to keep the structure of the code unchanged, I've updated things to: busy_ptr->nr_writebacks = 1 + (PPC_ONE_BIT_SET_P (out_vmask) ? 1 : 2); which silences the warning from clang, and is, I am guessing, what the original author intended. Diff: --- sim/ppc/altivec.igen | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sim/ppc/altivec.igen b/sim/ppc/altivec.igen index 63fe95a53d5..f3ad32d8825 100644 --- a/sim/ppc/altivec.igen +++ b/sim/ppc/altivec.igen @@ -231,7 +231,7 @@ void::model-function::ppc_insn_vr_vscr:itable_index index, model_data *model_ptr busy_ptr->vscr_busy = 1; if (out_vmask) - busy_ptr->nr_writebacks = 1 + (PPC_ONE_BIT_SET_P(out_vmask)) ? 1 : 2; + busy_ptr->nr_writebacks = 1 + (PPC_ONE_BIT_SET_P (out_vmask) ? 1 : 2); if (WITH_TRACE && ppc_trace[trace_model]) model_trace_altivec_make_busy(model_ptr, vr_mask, 0);
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