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r263172 - in /trunk/gcc: ChangeLog config/aarch...
- From: rearnsha at gcc dot gnu dot org
- To: gcc-cvs at gcc dot gnu dot org
- Date: Tue, 31 Jul 2018 17:36:09 -0000
- Subject: r263172 - in /trunk/gcc: ChangeLog config/aarch...
Author: rearnsha
Date: Tue Jul 31 17:36:09 2018
New Revision: 263172
URL: https://gcc.gnu.org/viewcvs?rev=263172&root=gcc&view=rev
Log:
AArch64 - disable CB[N]Z TB[N]Z when tracking speculation
The CB[N]Z and TB[N]Z instructions do not expose the comparison through
the condition code flags. This makes it impossible to track speculative
execution through such a branch. We can handle this relatively easily
by simply disabling the patterns in this case.
A side effect of this is that the split patterns for the atomic operations
need to also avoid generating these instructions. They mostly have simple
fall-backs for this already.
* config/aarch64/aarch64.md (cb<optab><mode>1): Disable when
aarch64_track_speculation is true.
(tb<optab><mode>1): Likewise.
* config/aarch64/aarch64.c (aarch64_split_compare_regs): Do not
generate CB[N]Z when tracking speculation.
(aarch64_split_compare_and_swap): Likewise.
(aarch64_split_atomic_op): Likewise.
Modified:
trunk/gcc/ChangeLog
trunk/gcc/config/aarch64/aarch64.c
trunk/gcc/config/aarch64/aarch64.md