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* [binutils-gdb] sim/ppc: fix for operator precedence warning from clang
@ 2022-10-24 16:19 Andrew Burgess
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From: Andrew Burgess @ 2022-10-24 16:19 UTC (permalink / raw)
To: gdb-cvs
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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2022-10-24 16:19 [binutils-gdb] sim/ppc: fix for operator precedence warning from clang Andrew Burgess
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