This changes the definition of t2DoLoopStart from
t2DoLoopStart rGPR
to
GPRlr = t2DoLoopStart rGPR
This will hopefully mean that low overhead loops are more tied together,
and we can more reliably generate loops without reverting or being at
the whims of the register allocator.
This is a fairly simple change in itself, but leads to a number of other
required alterations.
- The hardware loop pass, if UsePhi is set, now generates loops of the
form:
%start = llvm.start.loop.iterations(%N)
loop:
%p = phi [%start], [%dec]
%dec = llvm.loop.decrement.reg(%p, 1)
%c = icmp ne %dec, 0
br %c, loop, exit
- For this a new llvm.start.loop.iterations intrinsic was added, identical
to llvm.set.loop.iterations but produces a value as seen above, gluing
the loop together more through def-use chains.
- This new instrinsic conceptually produces the same output as input,
which is taught to SCEV so that the checks in MVETailPredication are not
affected.
- Some minor changes are needed to the ARMLowOverheadLoop pass, but it has
been left mostly as before. We should now more reliably be able to tell
that the t2DoLoopStart is correct without having to prove it, but
t2WhileLoopStart and tail-predicated loops will remain the same.
- And all the tests have been updated. There are a lot of them!
This patch on it's own might cause more trouble that it helps, with more
tail-predicated loops being reverted, but some additional patches can
hopefully improve upon that to get to something that is better overall.
Differential Revision: https://reviews.llvm.org/D89881
219 lines
11 KiB
YAML
219 lines
11 KiB
YAML
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
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# RUN: llc -mtriple=thumbv8.1m.main -mattr=+mve -run-pass=arm-low-overhead-loops %s -o - | FileCheck %s
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# I think this should be equivalent, but the calculation in the middle block
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# is too complex to process for now.
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--- |
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define dso_local i32 @wrong_vctp_liveout(i16* nocapture readonly %a, i16* nocapture readonly %b, i32 %N) local_unnamed_addr #0 {
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entry:
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%cmp9 = icmp eq i32 %N, 0
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%tmp = add i32 %N, 3
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%tmp1 = lshr i32 %tmp, 2
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%tmp2 = shl nuw i32 %tmp1, 2
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%tmp3 = add i32 %tmp2, -4
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%tmp4 = lshr i32 %tmp3, 2
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%tmp5 = add nuw nsw i32 %tmp4, 1
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br i1 %cmp9, label %for.cond.cleanup, label %vector.ph
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vector.ph: ; preds = %entry
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%start = call i32 @llvm.start.loop.iterations.i32(i32 %tmp5)
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br label %vector.body
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vector.body: ; preds = %vector.body, %vector.ph
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%lsr.iv1 = phi i32 [ %lsr.iv.next, %vector.body ], [ %start, %vector.ph ]
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%lsr.iv18 = phi i16* [ %scevgep19, %vector.body ], [ %b, %vector.ph ]
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%lsr.iv = phi i16* [ %scevgep, %vector.body ], [ %a, %vector.ph ]
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%vec.phi = phi <4 x i32> [ zeroinitializer, %vector.ph ], [ %tmp13, %vector.body ]
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%tmp7 = phi i32 [ %N, %vector.ph ], [ %tmp9, %vector.body ]
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%lsr.iv17 = bitcast i16* %lsr.iv to <4 x i16>*
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%lsr.iv1820 = bitcast i16* %lsr.iv18 to <4 x i16>*
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%tmp8 = call <4 x i1> @llvm.arm.mve.vctp32(i32 %tmp7)
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%tmp9 = sub i32 %tmp7, 4
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%wide.masked.load = call <4 x i16> @llvm.masked.load.v4i16.p0v4i16(<4 x i16>* %lsr.iv17, i32 2, <4 x i1> %tmp8, <4 x i16> undef)
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%tmp10 = sext <4 x i16> %wide.masked.load to <4 x i32>
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%wide.masked.load14 = call <4 x i16> @llvm.masked.load.v4i16.p0v4i16(<4 x i16>* %lsr.iv1820, i32 2, <4 x i1> %tmp8, <4 x i16> undef)
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%tmp11 = sext <4 x i16> %wide.masked.load14 to <4 x i32>
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%tmp12 = mul nsw <4 x i32> %tmp11, %tmp10
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%tmp13 = add <4 x i32> %tmp12, %vec.phi
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%scevgep = getelementptr i16, i16* %lsr.iv, i32 4
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%scevgep19 = getelementptr i16, i16* %lsr.iv18, i32 4
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%tmp14 = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 %lsr.iv1, i32 1)
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%tmp15 = icmp ne i32 %tmp14, 0
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%lsr.iv.next = add nsw i32 %lsr.iv1, -1
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br i1 %tmp15, label %vector.body, label %middle.block
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middle.block: ; preds = %vector.body
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%0 = add i32 %tmp9, 4
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%insert.idx = insertelement <4 x i32> undef, i32 %0, i32 0
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%idx.splat = shufflevector <4 x i32> %insert.idx, <4 x i32> undef, <4 x i32> zeroinitializer
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%n.minusone = add i32 %N, -1
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%insert.n = insertelement <4 x i32> undef, i32 %n.minusone, i32 0
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%n.splat = shufflevector <4 x i32> %insert.n, <4 x i32> undef, <4 x i32> zeroinitializer
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%tmp16 = icmp ult <4 x i32> %idx.splat, %n.splat
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%tmp17 = select <4 x i1> %tmp16, <4 x i32> %tmp13, <4 x i32> %vec.phi
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%tmp18 = call i32 @llvm.vector.reduce.add.v4i32(<4 x i32> %tmp17)
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br label %for.cond.cleanup
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for.cond.cleanup: ; preds = %middle.block, %entry
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%res.0.lcssa = phi i32 [ 0, %entry ], [ %tmp18, %middle.block ]
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ret i32 %res.0.lcssa
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}
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declare <4 x i16> @llvm.masked.load.v4i16.p0v4i16(<4 x i16>*, i32 immarg, <4 x i1>, <4 x i16>) #1
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declare i32 @llvm.vector.reduce.add.v4i32(<4 x i32>) #2
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declare i32 @llvm.start.loop.iterations.i32(i32) #3
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declare i32 @llvm.loop.decrement.reg.i32.i32.i32(i32, i32) #3
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declare <4 x i1> @llvm.arm.mve.vctp32(i32) #4
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...
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---
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name: wrong_vctp_liveout
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alignment: 2
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exposesReturnsTwice: false
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legalized: false
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regBankSelected: false
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selected: false
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failedISel: false
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tracksRegLiveness: true
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hasWinCFI: false
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registers: []
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liveins:
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- { reg: '$r0', virtual-reg: '' }
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- { reg: '$r1', virtual-reg: '' }
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- { reg: '$r2', virtual-reg: '' }
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frameInfo:
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isFrameAddressTaken: false
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isReturnAddressTaken: false
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hasStackMap: false
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hasPatchPoint: false
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stackSize: 8
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offsetAdjustment: 0
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maxAlignment: 4
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adjustsStack: false
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hasCalls: false
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stackProtector: ''
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maxCallFrameSize: 0
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cvBytesOfCalleeSavedRegisters: 0
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hasOpaqueSPAdjustment: false
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hasVAStart: false
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hasMustTailInVarArgFunc: false
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localFrameSize: 0
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savePoint: ''
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restorePoint: ''
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fixedStack: []
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stack:
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- { id: 0, name: '', type: spill-slot, offset: -4, size: 4, alignment: 4,
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stack-id: default, callee-saved-register: '$lr', callee-saved-restored: false,
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debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
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- { id: 1, name: '', type: spill-slot, offset: -8, size: 4, alignment: 4,
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stack-id: default, callee-saved-register: '$r7', callee-saved-restored: true,
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debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
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callSites: []
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constants: []
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machineFunctionInfo: {}
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body: |
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; CHECK-LABEL: name: wrong_vctp_liveout
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; CHECK: bb.0.entry:
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; CHECK: successors: %bb.1(0x80000000)
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; CHECK: liveins: $lr, $r0, $r1, $r2, $r7
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; CHECK: tCMPi8 renamable $r2, 0, 14 /* CC::al */, $noreg, implicit-def $cpsr
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; CHECK: t2IT 0, 4, implicit-def $itstate
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; CHECK: renamable $r0 = tMOVi8 $noreg, 0, 0 /* CC::eq */, $cpsr, implicit killed $r0, implicit $itstate
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; CHECK: tBX_RET 0 /* CC::eq */, killed $cpsr, implicit $r0, implicit killed $itstate
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; CHECK: bb.1.vector.ph:
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; CHECK: successors: %bb.2(0x80000000)
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; CHECK: liveins: $lr, $r0, $r1, $r2, $r7
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; CHECK: frame-setup tPUSH 14 /* CC::al */, $noreg, killed $r7, killed $lr, implicit-def $sp, implicit $sp
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; CHECK: frame-setup CFI_INSTRUCTION def_cfa_offset 8
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; CHECK: frame-setup CFI_INSTRUCTION offset $lr, -4
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; CHECK: frame-setup CFI_INSTRUCTION offset $r7, -8
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; CHECK: renamable $r3, dead $cpsr = tADDi3 renamable $r2, 3, 14 /* CC::al */, $noreg
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; CHECK: renamable $q1 = MVE_VMOVimmi32 0, 0, $noreg, undef renamable $q1
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; CHECK: renamable $r3 = t2BICri killed renamable $r3, 3, 14 /* CC::al */, $noreg, $noreg
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; CHECK: renamable $r12 = t2SUBri killed renamable $r3, 4, 14 /* CC::al */, $noreg, $noreg
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; CHECK: renamable $r3, dead $cpsr = tMOVi8 1, 14 /* CC::al */, $noreg
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; CHECK: renamable $r3 = nuw nsw t2ADDrs killed renamable $r3, killed renamable $r12, 19, 14 /* CC::al */, $noreg, $noreg
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; CHECK: dead $lr = t2DLS renamable $r3
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; CHECK: $r12 = tMOVr killed $r3, 14 /* CC::al */, $noreg
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; CHECK: $r3 = tMOVr $r2, 14 /* CC::al */, $noreg
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; CHECK: bb.2.vector.body:
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; CHECK: successors: %bb.2(0x7c000000), %bb.3(0x04000000)
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; CHECK: liveins: $q1, $r0, $r1, $r2, $r3, $r12
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; CHECK: renamable $vpr = MVE_VCTP32 renamable $r3, 0, $noreg
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; CHECK: $q0 = MVE_VORR killed $q1, killed $q1, 0, $noreg, undef $q0
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; CHECK: MVE_VPST 4, implicit $vpr
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; CHECK: renamable $r0, renamable $q1 = MVE_VLDRHS32_post killed renamable $r0, 8, 1, renamable $vpr :: (load 8 from %ir.lsr.iv17, align 2)
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; CHECK: renamable $r1, renamable $q2 = MVE_VLDRHS32_post killed renamable $r1, 8, 1, killed renamable $vpr :: (load 8 from %ir.lsr.iv1820, align 2)
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; CHECK: $lr = tMOVr $r12, 14 /* CC::al */, $noreg
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; CHECK: renamable $q1 = nsw MVE_VMULi32 killed renamable $q2, killed renamable $q1, 0, $noreg, undef renamable $q1
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; CHECK: renamable $r12 = nsw t2SUBri killed $r12, 1, 14 /* CC::al */, $noreg, $noreg
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; CHECK: renamable $r3, dead $cpsr = tSUBi8 killed renamable $r3, 4, 14 /* CC::al */, $noreg
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; CHECK: renamable $q1 = MVE_VADDi32 killed renamable $q1, renamable $q0, 0, $noreg, undef renamable $q1
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; CHECK: dead $lr = t2LEUpdate killed renamable $lr, %bb.2
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; CHECK: bb.3.middle.block:
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; CHECK: liveins: $q0, $q1, $r2, $r3
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; CHECK: renamable $r0, dead $cpsr = tSUBi3 killed renamable $r2, 1, 14 /* CC::al */, $noreg
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; CHECK: renamable $q2 = MVE_VDUP32 killed renamable $r0, 0, $noreg, undef renamable $q2
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; CHECK: renamable $r0, dead $cpsr = tADDi3 killed renamable $r3, 4, 14 /* CC::al */, $noreg
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; CHECK: renamable $vpr = MVE_VCMPu32r killed renamable $q2, killed renamable $r0, 8, 0, $noreg
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; CHECK: renamable $q0 = MVE_VPSEL killed renamable $q1, killed renamable $q0, 0, killed renamable $vpr
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; CHECK: renamable $r0 = MVE_VADDVu32no_acc killed renamable $q0, 0, $noreg
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; CHECK: tPOP_RET 14 /* CC::al */, $noreg, def $r7, def $pc, implicit killed $r0
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bb.0.entry:
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successors: %bb.1(0x80000000)
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liveins: $r0, $r1, $r2, $lr, $r7
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tCMPi8 renamable $r2, 0, 14, $noreg, implicit-def $cpsr
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t2IT 0, 4, implicit-def $itstate
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renamable $r0 = tMOVi8 $noreg, 0, 0, $cpsr, implicit killed $r0, implicit $itstate
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tBX_RET 0, killed $cpsr, implicit $r0, implicit killed $itstate
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bb.1.vector.ph:
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successors: %bb.2(0x80000000)
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liveins: $r0, $r1, $r2, $lr, $r7
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frame-setup tPUSH 14, $noreg, killed $r7, killed $lr, implicit-def $sp, implicit $sp
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frame-setup CFI_INSTRUCTION def_cfa_offset 8
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frame-setup CFI_INSTRUCTION offset $lr, -4
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frame-setup CFI_INSTRUCTION offset $r7, -8
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renamable $r3, dead $cpsr = tADDi3 renamable $r2, 3, 14, $noreg
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renamable $q1 = MVE_VMOVimmi32 0, 0, $noreg, undef renamable $q1
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renamable $r3 = t2BICri killed renamable $r3, 3, 14, $noreg, $noreg
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renamable $r12 = t2SUBri killed renamable $r3, 4, 14, $noreg, $noreg
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renamable $r3, dead $cpsr = tMOVi8 1, 14, $noreg
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renamable $r3 = nuw nsw t2ADDrs killed renamable $r3, killed renamable $r12, 19, 14, $noreg, $noreg
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$lr = t2DoLoopStart renamable $r3
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$r12 = tMOVr killed $r3, 14, $noreg
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$r3 = tMOVr $r2, 14, $noreg
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bb.2.vector.body:
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successors: %bb.2(0x7c000000), %bb.3(0x04000000)
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liveins: $q1, $r0, $r1, $r2, $r3, $r12
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renamable $vpr = MVE_VCTP32 renamable $r3, 0, $noreg
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$q0 = MVE_VORR killed $q1, $q1, 0, $noreg, undef $q0
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MVE_VPST 4, implicit $vpr
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renamable $r0, renamable $q1 = MVE_VLDRHS32_post killed renamable $r0, 8, 1, renamable $vpr :: (load 8 from %ir.lsr.iv17, align 2)
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renamable $r1, renamable $q2 = MVE_VLDRHS32_post killed renamable $r1, 8, 1, killed renamable $vpr :: (load 8 from %ir.lsr.iv1820, align 2)
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$lr = tMOVr $r12, 14, $noreg
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renamable $q1 = nsw MVE_VMULi32 killed renamable $q2, killed renamable $q1, 0, $noreg, undef renamable $q1
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renamable $r12 = nsw t2SUBri killed $r12, 1, 14, $noreg, $noreg
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renamable $r3, dead $cpsr = tSUBi8 killed renamable $r3, 4, 14, $noreg
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renamable $q1 = MVE_VADDi32 killed renamable $q1, renamable $q0, 0, $noreg, undef renamable $q1
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renamable $lr = t2LoopDec killed renamable $lr, 1
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t2LoopEnd killed renamable $lr, %bb.2, implicit-def dead $cpsr
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tB %bb.3, 14, $noreg
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bb.3.middle.block:
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liveins: $q0, $q1, $r2, $r3
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renamable $r0, dead $cpsr = tSUBi3 killed renamable $r2, 1, 14, $noreg
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renamable $q2 = MVE_VDUP32 killed renamable $r0, 0, $noreg, undef renamable $q2
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renamable $r0, dead $cpsr = tADDi3 killed renamable $r3, 4, 14, $noreg
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renamable $vpr = MVE_VCMPu32r killed renamable $q2, killed renamable $r0, 8, 0, $noreg
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renamable $q0 = MVE_VPSEL killed renamable $q1, killed renamable $q0, 0, killed renamable $vpr
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renamable $r0 = MVE_VADDVu32no_acc killed renamable $q0, 0, $noreg
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tPOP_RET 14, $noreg, def $r7, def $pc, implicit killed $r0
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...
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