2018-03-21 03:35:09 +08:00
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; RUN: llc -march=hexagon -enable-pipeliner -enable-bsb-sched=0 -join-liveintervals=false < %s | FileCheck %s
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[CodeGen] Add a new pass for PostRA sink
Summary:
This pass sinks COPY instructions into a successor block, if the COPY is not
used in the current block and the COPY is live-in to a single successor
(i.e., doesn't require the COPY to be duplicated). This avoids executing the
the copy on paths where their results aren't needed. This also exposes
additional opportunites for dead copy elimination and shrink wrapping.
These copies were either not handled by or are inserted after the MachineSink
pass. As an example of the former case, the MachineSink pass cannot sink
COPY instructions with allocatable source registers; for AArch64 these type
of copy instructions are frequently used to move function parameters (PhyReg)
into virtual registers in the entry block..
For the machine IR below, this pass will sink %w19 in the entry into its
successor (%bb.1) because %w19 is only live-in in %bb.1.
```
%bb.0:
%wzr = SUBSWri %w1, 1
%w19 = COPY %w0
Bcc 11, %bb.2
%bb.1:
Live Ins: %w19
BL @fun
%w0 = ADDWrr %w0, %w19
RET %w0
%bb.2:
%w0 = COPY %wzr
RET %w0
```
As we sink %w19 (CSR in AArch64) into %bb.1, the shrink-wrapping pass will be
able to see %bb.0 as a candidate.
With this change I observed 12% more shrink-wrapping candidate and 13% more dead copies deleted in spec2000/2006/2017 on AArch64.
Reviewers: qcolombet, MatzeB, thegameg, mcrosier, gberry, hfinkel, john.brawn, twoh, RKSimon, sebpop, kparzysz
Reviewed By: sebpop
Subscribers: evandro, sebpop, sfertile, aemerson, mgorny, javed.absar, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D41463
llvm-svn: 328237
2018-03-23 04:06:47 +08:00
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; XFAIL: *
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; This test is failing after post-ra machine sinking.
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2018-03-21 03:35:09 +08:00
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; Test that we generate the correct Phi values when there is a Phi that
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; references another Phi. We need to examine the other Phi to get the
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; correct value. We need to do this even if we haven't generated the
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; kernel code for the other Phi yet.
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2018-03-27 00:33:16 +08:00
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; CHECK: v[[REG0:[0-9]+]] = v[[REG1:[0-9]+]]
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2018-03-21 03:35:09 +08:00
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; CHECK: loop0
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2018-03-27 00:33:16 +08:00
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; Check for copy REG0 = REG1 (via vcombine):
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; CHECK: v{{[0-9]+}}:[[REG0]] = vcombine(v{{[0-9]+}},v[[REG1]])
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2018-03-21 03:35:09 +08:00
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; CHECK: endloop0
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; Function Attrs: nounwind
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define void @f0() #0 {
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b0:
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br i1 undef, label %b1, label %b2
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b1: ; preds = %b1, %b0
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%v0 = phi i32 [ %v7, %b1 ], [ 0, %b0 ]
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%v1 = phi <16 x i32> [ %v4, %b1 ], [ undef, %b0 ]
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%v2 = phi <16 x i32> [ %v1, %b1 ], [ undef, %b0 ]
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%v3 = tail call <16 x i32> @llvm.hexagon.V6.valignb(<16 x i32> %v1, <16 x i32> %v2, i32 62)
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%v4 = tail call <16 x i32> @llvm.hexagon.V6.vaddh(<16 x i32> undef, <16 x i32> undef)
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%v5 = tail call <16 x i32> @llvm.hexagon.V6.valignb(<16 x i32> %v4, <16 x i32> %v1, i32 2)
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%v6 = tail call <16 x i32> @llvm.hexagon.V6.vabsdiffh(<16 x i32> %v3, <16 x i32> %v5)
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store <16 x i32> %v6, <16 x i32>* null, align 64
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%v7 = add nsw i32 %v0, 1
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%v8 = icmp slt i32 %v7, undef
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br i1 %v8, label %b1, label %b2
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b2: ; preds = %b1, %b0
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ret void
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}
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; Function Attrs: nounwind readnone
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declare <16 x i32> @llvm.hexagon.V6.vaddh(<16 x i32>, <16 x i32>) #1
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; Function Attrs: nounwind readnone
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declare <16 x i32> @llvm.hexagon.V6.valignb(<16 x i32>, <16 x i32>, i32) #1
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; Function Attrs: nounwind readnone
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declare <16 x i32> @llvm.hexagon.V6.vabsdiffh(<16 x i32>, <16 x i32>) #1
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attributes #0 = { nounwind "target-cpu"="hexagonv60" "target-features"="+hvxv60,+hvx-length64b" }
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attributes #1 = { nounwind readnone }
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