[PATCH ARM]Define LOGICAL_OP_NON_SHORT_CIRCUIT for ARM target

[Bin Cheng]

> -----Original Message-----
> From: Ramana Radhakrishnan [mailto:ramana.gcc@googlemail.com]
> Sent: Wednesday, November 21, 2012 6:02 AM
> To: Bin Cheng
> Cc: gcc-patches@gcc.gnu.org
> Subject: Re: [PATCH ARM]Define LOGICAL_OP_NON_SHORT_CIRCUIT for ARM target
> 
> On Fri, Nov 16, 2012 at 5:37 AM, Bin Cheng <bin.cheng@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.
I will file a bug about this later.

> 
> >
> >
> > 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.cheng@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.cheng@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.

Committed as r193687 in TRUNK.
I did not change test case gcc.dg/pr19105.c because Jakub had a patch also
fixing this and already got approved/committed. See
http://gcc.gnu.org/ml/gcc-patches/2012-11/msg00361.html

Thanks