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llvm-mirror/test/CodeGen/ARM/vldm-liveness.mir
Eli Friedman c3db369888 [ARM] Check correct instructions for load/store rescheduling.
This code starts from the high end of the sorted vector of offsets, and
works backwards: it tries to find contiguous offsets, process them, then
pops them from the end of the vector. Most of the code agrees with this
order of processing, but one loop doesn't: it instead processes elements
from the low end of the vector (which are nodes with unrelated offsets).
Fix that loop to process the correct elements.
    
This has a few implications. One, we don't incorrectly return early when
processing multiple groups of offsets in the same block (which allows
rescheduling prera-ldst-insertpt.mir). Two, we pick the correct insert
point for loads, so they're correctly sorted (which affects the
scheduling of vldm-liveness.ll). I think it might also impact some of
the heuristics slightly.
    
Differential Revision: https://reviews.llvm.org/D30368

llvm-svn: 296701
2017-03-01 22:56:20 +00:00

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# RUN: llc -run-pass arm-ldst-opt -verify-machineinstrs %s -o - | FileCheck %s
# ARM load store optimizer was dealing with a sequence like:
# s1 = VLDRS [r0, 1], Q0<imp-def>
# s3 = VLDRS [r0, 2], Q0<imp-use,kill>, Q0<imp-def>
# s0 = VLDRS [r0, 0], Q0<imp-use,kill>, Q0<imp-def>
# s2 = VLDRS [r0, 4], Q0<imp-use,kill>, Q0<imp-def>
#
# It decided to combine the {s0, s1} loads into a single instruction in the
# third position. However, this leaves the instruction defining s3 with a stray
# imp-use of Q0, which is undefined.
#
# The verifier catches this, so this test just makes sure that appropriate
# liveness flags are added.
--- |
target triple = "thumbv7-apple-ios"
define arm_aapcs_vfpcc <4 x float> @foo(float* %ptr) {
ret <4 x float> undef
}
...
---
name: foo
alignment: 1
liveins:
- { reg: '%r0' }
body: |
bb.0 (%ir-block.0):
liveins: %r0
%s1 = VLDRS %r0, 1, 14, _, implicit-def %q0 :: (load 4)
%s3 = VLDRS %r0, 2, 14, _, implicit killed %q0, implicit-def %q0 :: (load 4)
; CHECK: %s3 = VLDRS %r0, 2, 14, _, implicit killed undef %q0, implicit-def %q0 :: (load 4)
%s0 = VLDRS %r0, 0, 14, _, implicit killed %q0, implicit-def %q0 :: (load 4)
; CHECK: VLDMSIA %r0, 14, _, def %s0, def %s1, implicit-def _
%s2 = VLDRS killed %r0, 4, 14, _, implicit killed %q0, implicit-def %q0 :: (load 4)
; CHECK: %s2 = VLDRS killed %r0, 4, 14, _, implicit killed %q0, implicit-def %q0 :: (load 4)
tBX_RET 14, _, implicit %q0
...