On Fri, Nov 16, 2012 at 5:37 AM, Bin Cheng <bin.ch...@arm.com> wrote: > Hi, > This patch defines LOGICAL_OP_NON_SHORT_CIRCUIT for ARM target and prefers > short circuit for armv6-m and Thumb2+Os. > > I tested the patch on arm-none-eabi on armv6-m/Thumb2 for both Os/O2. The > patch introduces new fails on ARMv6-m: > > gcc/testsuite/gcc.dg/pr19105.c > gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-4.c > gcc/testsuite/gcc.dg/tree-ssa/vrp47.c > These tests depends on non-short-circuit IR, which is not generated > because we prefer short circuit on ARMv6-m now. I modified the tests to skip > them on ARMv6-m. > > gcc/testsuite/gcc.dg/uninit-pred-8_b.c > Root cause: tree-ssa-uninit.c computes control dependent chain for > uses/def of variable and checks whether each use is guarded by def. It has a > upper bound on the number of control dependent chains(MAX_NUM_CHAINS==8) and > just retreat to false warning if the number of chains exceeds > MAX_NUM_CHAINS. In our scenario, the number of chains exceeds MAX_NUM_CHAINS > because we prefer short circuit now, resulting in false warning information. > These false warning cannot be fully removed if the MAX_NUM_CHAINS exists, > but we can improve it in following way: There are lots of invalid control > dependent chains computed in tree-ssa-uninit.c now and should be pruned. I > have already implemented a quick fix and it works for our scenario. I can > take this problem once I get some time.
Please keep track of this in a separate bugzilla entry. > > > This is an backend patch and not a bug fix, I am not sure whether it can go > in trunk or I have to wait for GCC4.9? OK for trunk. Ramana > > Thanks > > 2012-11-16 Bin Cheng <bin.ch...@arm.com> > > * config/arm/arm-cores.def (cortex-m1, cortex-m0) > (cortex-m0plus): Use v6m. > * config/arm/arm-protos.h (tune_params): Add > logical_op_non_short_circuit. > * config/arm/arm.c (arm_slowmul_tune, arm_fastmul_tune) > (arm_strongarm_tune, arm_xscale_tune, arm_9e_tune, arm_v6t2_tune) > (arm_cortex_tune, arm_cortex_a15_tune, arm_cortex_a5_tune) > (arm_cortex_a9_tune, arm_fa726te_tune): Set > logical_op_non_short_circuit field. > (arm_v6m_tune): New tune_params struct. > * config/arm/arm.h (LOGICAL_OP_NON_SHORT_CIRCUIT): Define. > > gcc/testsuite/ChangeLog > 2012-11-16 Bin Cheng <bin.ch...@arm.com> > > * gcc.dg/pr19105.c: Skip on armv6-m. > * gcc.dg/tree-ssa/ssa-dom-thread-4.c: Ditto. > * gcc.dg/tree-ssa/vrp47.c: Ditto.
