1. Fix pre-ra scheduler so it doesn't try to push instructions above calls to
"optimize for latency". Call instructions don't have the right latency and
this is more likely to use introduce spills.
2. Fix if-converter cost function. For ARM, it should use instruction latencies,
not # of micro-ops since multi-latency instructions is completely executed
even when the predicate is false. Also, some instruction will be "slower"
when they are predicated due to the register def becoming implicit input.
rdar://8598427
llvm-svn: 118135
at more than those which define CPSR. You can have this situation:
(1) subs ...
(2) sub r6, r5, r4
(3) movge ...
(4) cmp r6, 0
(5) movge ...
We cannot convert (2) to "subs" because (3) is using the CPSR set by
(1). There's an analogous situation here:
(1) sub r1, r2, r3
(2) sub r4, r5, r6
(3) cmp r4, ...
(5) movge ...
(6) cmp r1, ...
(7) movge ...
We cannot convert (1) to "subs" because of the intervening use of CPSR.
llvm-svn: 117950
- For now, loads of [r, r] addressing mode is the same as the
[r, r lsl/lsr/asr #] variants. ARMBaseInstrInfo::getOperandLatency() should
identify the former case and reduce the output latency by 1.
- Also identify [r, r << 2] case. This special form of shifter addressing mode
is "free".
llvm-svn: 117519
elements than the result vector type. So, when an instruction like:
%8 = shufflevector <2 x float> %4, <2 x float> %7, <4 x i32> <i32 1, i32 0, i32 3, i32 2>
is translated to a DAG, each operand is changed to a concat_vectors node that appends 2 undef elements. That is:
shuffle [a,b], [c,d] is changed to:
shuffle [a,b,u,u], [c,d,u,u]
That's probably the right thing for x86 but for NEON, we'd much rather have:
shuffle [a,b,c,d], undef
Teach the DAG combiner how to do that transformation for ARM. Radar 8597007.
llvm-svn: 117482
do not double-count the duplicate instructions by counting once from the
beginning and again from the end. Keep track of where the duplicates from
the beginning ended and don't go past that point when counting duplicates
at the end. Radar 8589805.
This change causes one of the MC/ARM/simple-fp-encoding tests to produce
different (better!) code without the vmovne instruction being tested.
I changed the test to produce vmovne and vmoveq instructions but moving
between register files in the opposite direction. That's not quite the same
but predicated versions of those instructions weren't being tested before,
so at least the test coverage is not any worse, just different.
llvm-svn: 117333
"long latency" enough to hoist even if it may increase spilling. Reloading
a value from spill slot is often cheaper than performing an expensive
computation in the loop. For X86, that means machine LICM will hoist
SQRT, DIV, etc. ARM will be somewhat aggressive with VFP and NEON
instructions.
- Enable register pressure aware machine LICM by default.
llvm-svn: 116781
have been printed with the "S" modifier after the predicate. With ARM's
unified syntax, they are supposed to go in the other order. We fixed this
for Thumb when we switched to unified syntax but missed changing it for
ARM. Apparently we don't generate these instructions often because no one
noticed until now. Thanks to Bill Wendling for the testcase!
llvm-svn: 116563
1. Cortex-A8 load / store multiplies can only issue on ALU0.
2. Eliminate A8_Issue, A8_LSPipe will correctly limit the load / store issues.
3. Correctly model all vld1 and vld2 variants.
llvm-svn: 116134
callee-saved registers at the end of the lists. Also prefer to avoid using
the low registers that are in register subclasses required by certain
instructions, so that those registers will more likely be available when needed.
This change makes a huge improvement in spilling in some cases. Thanks to
Jakob for helping me realize the problem.
Most of this patch is fixing the testsuite. There are quite a few places
where we're checking for specific registers. I changed those to wildcards
in places where that doesn't weaken the tests. The spill-q.ll and
thumb2-spill-q.ll tests stopped spilling with this change, so I added a bunch
of live values to force spills on those tests.
llvm-svn: 116055
allow target to correctly compute latency for cases where static scheduling
itineraries isn't sufficient. e.g. variable_ops instructions such as
ARM::ldm.
This also allows target without scheduling itineraries to compute operand
latencies. e.g. X86 can return (approximated) latencies for high latency
instructions such as division.
- Compute operand latencies for those defined by load multiple instructions,
e.g. ldm and those used by store multiple instructions, e.g. stm.
llvm-svn: 115755
Evan Cheng