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Software pipelining is an optimization for improving ILP by overlapping loop iterations. Swing Modulo Scheduling (SMS) is an implementation of software pipelining that attempts to reduce register pressure and generate efficient pipelines with a low compile-time cost. This implementaion of SMS is a target-independent back-end pass. When enabled, the pass should run just prior to the register allocation pass, while the machine IR is in SSA form. If the pass is successful, then the original loop is replaced by the optimized loop. The optimized loop contains one or more prolog blocks, the pipelined kernel, and one or more epilog blocks. This pass is enabled for Hexagon only. To enable for other targets, a couple of target specific hooks must be implemented, and the pass needs to be called from the target's TargetMachine implementation. Differential Review: http://reviews.llvm.org/D16829 llvm-svn: 277169
43 lines
1.5 KiB
LLVM
43 lines
1.5 KiB
LLVM
; RUN: llc -march=hexagon -mcpu=hexagonv5 -enable-pipeliner \
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; RUN: -pipeliner-max-stages=2 < %s | FileCheck %s
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@A = global [8 x i32] [i32 4, i32 -3, i32 5, i32 -2, i32 -1, i32 2, i32 6, i32 -2], align 8
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define i32 @test(i32 %Left, i32 %Right) {
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entry:
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%add = add nsw i32 %Right, %Left
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%div = sdiv i32 %add, 2
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%cmp9 = icmp slt i32 %div, %Left
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br i1 %cmp9, label %for.end, label %for.body.preheader
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for.body.preheader:
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br label %for.body
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; CHECK: loop0(.LBB0_[[LOOP:.]],
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; CHECK: .LBB0_[[LOOP]]:
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; CHECK: [[REG1:(r[0-9]+)]] = max(r{{[0-9]+}}, [[REG1]])
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; CHECK: [[REG0:(r[0-9]+)]] = add([[REG2:(r[0-9]+)]], [[REG0]])
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; CHECK: [[REG2]] = memw
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; CHECK: endloop0
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for.body:
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%MaxLeftBorderSum.012 = phi i32 [ %MaxLeftBorderSum.1, %for.body ], [ 0, %for.body.preheader ]
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%i.011 = phi i32 [ %dec, %for.body ], [ %div, %for.body.preheader ]
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%LeftBorderSum.010 = phi i32 [ %add1, %for.body ], [ 0, %for.body.preheader ]
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%arrayidx = getelementptr inbounds [8 x i32], [8 x i32]* @A, i32 0, i32 %i.011
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%0 = load i32, i32* %arrayidx, align 4
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%add1 = add nsw i32 %0, %LeftBorderSum.010
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%cmp2 = icmp sgt i32 %add1, %MaxLeftBorderSum.012
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%MaxLeftBorderSum.1 = select i1 %cmp2, i32 %add1, i32 %MaxLeftBorderSum.012
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%dec = add nsw i32 %i.011, -1
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%cmp = icmp slt i32 %dec, %Left
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br i1 %cmp, label %for.end.loopexit, label %for.body
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for.end.loopexit:
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br label %for.end
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for.end:
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%MaxLeftBorderSum.0.lcssa = phi i32 [ 0, %entry ], [ %MaxLeftBorderSum.1, %for.end.loopexit ]
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ret i32 %MaxLeftBorderSum.0.lcssa
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}
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