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Whitney Tsang 509d3200f9 [LoopNest]: Analysis to discover properties of a loop nest.
Summary: This patch adds an analysis pass to collect loop nests and
summarize properties of the nest (e.g the nest depth, whether the nest
is perfect, what's the innermost loop, etc...).

The motivation for this patch was discussed at the latest meeting of the
LLVM loop group (https://ibm.box.com/v/llvm-loop-nest-analysis) where we
discussed
the unimodular loop transformation framework ( “A Loop Transformation
Theory and an Algorithm to Maximize Parallelism”, Michael E. Wolf and
Monica S. Lam, IEEE TPDS, October 1991). The unimodular framework
provides a convenient way to unify legality checking and code generation
for several loop nest transformations (e.g. loop reversal, loop
interchange, loop skewing) and their compositions. Given that the
unimodular framework is applicable to perfect loop nests this is one
property of interest we expose in this analysis. Several other utility
functions are also provided. In the future other properties of interest
can be added in a centralized place.
Authored By: etiotto
Reviewer: Meinersbur, bmahjour, kbarton, Whitney, dmgreen, fhahn,
reames, hfinkel, jdoerfert, ppc-slack
Reviewed By: Meinersbur
Subscribers: bryanpkc, ppc-slack, mgorny, hiraditya, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D68789
2020-03-03 18:25:19 +00:00

276 lines
9.9 KiB
LLVM

; RUN: opt < %s -passes='print<loopnest>' -disable-output 2>&1 | FileCheck %s
; Test a perfect 2-dim loop nest of the form:
; for(i=0; i<nx; ++i)
; for(j=0; j<nx; ++j)
; y[i][j] = x[i][j];
define void @perf_nest_2D_1(i32** %y, i32** %x, i64 signext %nx, i64 signext %ny) {
; CHECK-LABEL: IsPerfect=true, Depth=1, OutermostLoop: perf_nest_2D_1_loop_j, Loops: ( perf_nest_2D_1_loop_j )
; CHECK-LABEL: IsPerfect=true, Depth=2, OutermostLoop: perf_nest_2D_1_loop_i, Loops: ( perf_nest_2D_1_loop_i perf_nest_2D_1_loop_j )
entry:
br label %perf_nest_2D_1_loop_i
perf_nest_2D_1_loop_i:
%i = phi i64 [ 0, %entry ], [ %inc13, %inc_i ]
%cmp21 = icmp slt i64 0, %ny
br i1 %cmp21, label %perf_nest_2D_1_loop_j, label %inc_i
perf_nest_2D_1_loop_j:
%j = phi i64 [ 0, %perf_nest_2D_1_loop_i ], [ %inc, %inc_j ]
%arrayidx = getelementptr inbounds i32*, i32** %x, i64 %j
%0 = load i32*, i32** %arrayidx, align 8
%arrayidx6 = getelementptr inbounds i32, i32* %0, i64 %j
%1 = load i32, i32* %arrayidx6, align 4
%arrayidx8 = getelementptr inbounds i32*, i32** %y, i64 %j
%2 = load i32*, i32** %arrayidx8, align 8
%arrayidx11 = getelementptr inbounds i32, i32* %2, i64 %i
store i32 %1, i32* %arrayidx11, align 4
br label %inc_j
inc_j:
%inc = add nsw i64 %j, 1
%cmp2 = icmp slt i64 %inc, %ny
br i1 %cmp2, label %perf_nest_2D_1_loop_j, label %inc_i
inc_i:
%inc13 = add nsw i64 %i, 1
%cmp = icmp slt i64 %inc13, %nx
br i1 %cmp, label %perf_nest_2D_1_loop_i, label %perf_nest_2D_1_loop_i_end
perf_nest_2D_1_loop_i_end:
ret void
}
; Test a perfect 2-dim loop nest of the form:
; for (i=0; i<100; ++i)
; for (j=0; j<100; ++j)
; y[i][j] = x[i][j];
define void @perf_nest_2D_2(i32** %y, i32** %x) {
; CHECK-LABEL: IsPerfect=true, Depth=1, OutermostLoop: perf_nest_2D_2_loop_j, Loops: ( perf_nest_2D_2_loop_j )
; CHECK-LABEL: IsPerfect=true, Depth=2, OutermostLoop: perf_nest_2D_2_loop_i, Loops: ( perf_nest_2D_2_loop_i perf_nest_2D_2_loop_j )
entry:
br label %perf_nest_2D_2_loop_i
perf_nest_2D_2_loop_i:
%i = phi i64 [ 0, %entry ], [ %inc13, %inc_i ]
br label %perf_nest_2D_2_loop_j
perf_nest_2D_2_loop_j:
%j = phi i64 [ 0, %perf_nest_2D_2_loop_i ], [ %inc, %inc_j ]
%arrayidx = getelementptr inbounds i32*, i32** %x, i64 %j
%0 = load i32*, i32** %arrayidx, align 8
%arrayidx6 = getelementptr inbounds i32, i32* %0, i64 %j
%1 = load i32, i32* %arrayidx6, align 4
%arrayidx8 = getelementptr inbounds i32*, i32** %y, i64 %j
%2 = load i32*, i32** %arrayidx8, align 8
%arrayidx11 = getelementptr inbounds i32, i32* %2, i64 %i
store i32 %1, i32* %arrayidx11, align 4
br label %inc_j
inc_j:
%inc = add nsw i64 %j, 1
%cmp2 = icmp slt i64 %inc, 100
br i1 %cmp2, label %perf_nest_2D_2_loop_j, label %loop_j_end
loop_j_end:
br label %inc_i
inc_i:
%inc13 = add nsw i64 %i, 1
%cmp = icmp slt i64 %inc13, 100
br i1 %cmp, label %perf_nest_2D_2_loop_i, label %perf_nest_2D_2_loop_i_end
perf_nest_2D_2_loop_i_end:
ret void
}
; Test a perfect 3-dim loop nest of the form:
; for (i=0; i<nx; ++i)
; for (j=0; j<ny; ++j)
; for (k=0; j<nk; ++k)
; y[j][j][k] = x[i][j][k];
;
define void @perf_nest_3D_1(i32*** %y, i32*** %x, i32 signext %nx, i32 signext %ny, i32 signext %nk) {
; CHECK-LABEL: IsPerfect=true, Depth=1, OutermostLoop: perf_nest_3D_1_loop_k, Loops: ( perf_nest_3D_1_loop_k )
; CHECK-NEXT: IsPerfect=true, Depth=2, OutermostLoop: perf_nest_3D_1_loop_j, Loops: ( perf_nest_3D_1_loop_j perf_nest_3D_1_loop_k )
; CHECK-NEXT: IsPerfect=true, Depth=3, OutermostLoop: perf_nest_3D_1_loop_i, Loops: ( perf_nest_3D_1_loop_i perf_nest_3D_1_loop_j perf_nest_3D_1_loop_k )
entry:
br label %perf_nest_3D_1_loop_i
perf_nest_3D_1_loop_i:
%i = phi i32 [ 0, %entry ], [ %inci, %for.inci ]
%cmp21 = icmp slt i32 0, %ny
br i1 %cmp21, label %perf_nest_3D_1_loop_j, label %for.inci
perf_nest_3D_1_loop_j:
%j = phi i32 [ 0, %perf_nest_3D_1_loop_i ], [ %incj, %for.incj ]
%cmp22 = icmp slt i32 0, %nk
br i1 %cmp22, label %perf_nest_3D_1_loop_k, label %for.incj
perf_nest_3D_1_loop_k:
%k = phi i32 [ 0, %perf_nest_3D_1_loop_j ], [ %inck, %for.inck ]
%idxprom = sext i32 %i to i64
%arrayidx = getelementptr inbounds i32**, i32*** %x, i64 %idxprom
%0 = load i32**, i32*** %arrayidx, align 8
%idxprom7 = sext i32 %j to i64
%arrayidx8 = getelementptr inbounds i32*, i32** %0, i64 %idxprom7
%1 = load i32*, i32** %arrayidx8, align 8
%idxprom9 = sext i32 %k to i64
%arrayidx10 = getelementptr inbounds i32, i32* %1, i64 %idxprom9
%2 = load i32, i32* %arrayidx10, align 4
%idxprom11 = sext i32 %j to i64
%arrayidx12 = getelementptr inbounds i32**, i32*** %y, i64 %idxprom11
%3 = load i32**, i32*** %arrayidx12, align 8
%idxprom13 = sext i32 %j to i64
%arrayidx14 = getelementptr inbounds i32*, i32** %3, i64 %idxprom13
%4 = load i32*, i32** %arrayidx14, align 8
%idxprom15 = sext i32 %k to i64
%arrayidx16 = getelementptr inbounds i32, i32* %4, i64 %idxprom15
store i32 %2, i32* %arrayidx16, align 4
br label %for.inck
for.inck:
%inck = add nsw i32 %k, 1
%cmp5 = icmp slt i32 %inck, %nk
br i1 %cmp5, label %perf_nest_3D_1_loop_k, label %for.incj
for.incj:
%incj = add nsw i32 %j, 1
%cmp2 = icmp slt i32 %incj, %ny
br i1 %cmp2, label %perf_nest_3D_1_loop_j, label %for.inci
for.inci:
%inci = add nsw i32 %i, 1
%cmp = icmp slt i32 %inci, %nx
br i1 %cmp, label %perf_nest_3D_1_loop_i, label %perf_nest_3D_1_loop_i_end
perf_nest_3D_1_loop_i_end:
ret void
}
; Test a perfect 3-dim loop nest of the form:
; for (i=0; i<100; ++i)
; for (j=0; j<100; ++j)
; for (k=0; j<100; ++k)
; y[j][j][k] = x[i][j][k];
;
define void @perf_nest_3D_2(i32*** %y, i32*** %x) {
; CHECK-LABEL: IsPerfect=true, Depth=1, OutermostLoop: perf_nest_3D_2_loop_k, Loops: ( perf_nest_3D_2_loop_k )
; CHECK-NEXT: IsPerfect=true, Depth=2, OutermostLoop: perf_nest_3D_2_loop_j, Loops: ( perf_nest_3D_2_loop_j perf_nest_3D_2_loop_k )
; CHECK-NEXT: IsPerfect=true, Depth=3, OutermostLoop: perf_nest_3D_2_loop_i, Loops: ( perf_nest_3D_2_loop_i perf_nest_3D_2_loop_j perf_nest_3D_2_loop_k )
entry:
br label %perf_nest_3D_2_loop_i
perf_nest_3D_2_loop_i:
%i = phi i32 [ 0, %entry ], [ %inci, %for.inci ]
br label %perf_nest_3D_2_loop_j
perf_nest_3D_2_loop_j:
%j = phi i32 [ 0, %perf_nest_3D_2_loop_i ], [ %incj, %for.incj ]
br label %perf_nest_3D_2_loop_k
perf_nest_3D_2_loop_k:
%k = phi i32 [ 0, %perf_nest_3D_2_loop_j ], [ %inck, %for.inck ]
%idxprom = sext i32 %i to i64
%arrayidx = getelementptr inbounds i32**, i32*** %x, i64 %idxprom
%0 = load i32**, i32*** %arrayidx, align 8
%idxprom7 = sext i32 %j to i64
%arrayidx8 = getelementptr inbounds i32*, i32** %0, i64 %idxprom7
%1 = load i32*, i32** %arrayidx8, align 8
%idxprom9 = sext i32 %k to i64
%arrayidx10 = getelementptr inbounds i32, i32* %1, i64 %idxprom9
%2 = load i32, i32* %arrayidx10, align 4
%idxprom11 = sext i32 %j to i64
%arrayidx12 = getelementptr inbounds i32**, i32*** %y, i64 %idxprom11
%3 = load i32**, i32*** %arrayidx12, align 8
%idxprom13 = sext i32 %j to i64
%arrayidx14 = getelementptr inbounds i32*, i32** %3, i64 %idxprom13
%4 = load i32*, i32** %arrayidx14, align 8
%idxprom15 = sext i32 %k to i64
%arrayidx16 = getelementptr inbounds i32, i32* %4, i64 %idxprom15
store i32 %2, i32* %arrayidx16, align 4
br label %for.inck
for.inck:
%inck = add nsw i32 %k, 1
%cmp5 = icmp slt i32 %inck, 100
br i1 %cmp5, label %perf_nest_3D_2_loop_k, label %loop_k_end
loop_k_end:
br label %for.incj
for.incj:
%incj = add nsw i32 %j, 1
%cmp2 = icmp slt i32 %incj, 100
br i1 %cmp2, label %perf_nest_3D_2_loop_j, label %loop_j_end
loop_j_end:
br label %for.inci
for.inci:
%inci = add nsw i32 %i, 1
%cmp = icmp slt i32 %inci, 100
br i1 %cmp, label %perf_nest_3D_2_loop_i, label %perf_nest_3D_2_loop_i_end
perf_nest_3D_2_loop_i_end:
ret void
}
; Test a perfect loop nest with a live out reduction:
; for (i = 0; i<ni; ++i)
; if (0<nj) { // guard branch for the j-loop
; for (j=0; j<nj; j+=1)
; x+=(i+j);
; }
; return x;
define signext i32 @perf_nest_live_out(i32 signext %x, i32 signext %ni, i32 signext %nj) {
; CHECK-LABEL: IsPerfect=true, Depth=1, OutermostLoop: perf_nest_live_out_loop_j, Loops: ( perf_nest_live_out_loop_j )
; CHECK-LABEL: IsPerfect=true, Depth=2, OutermostLoop: perf_nest_live_out_loop_i, Loops: ( perf_nest_live_out_loop_i perf_nest_live_out_loop_j )
entry:
%cmp4 = icmp slt i32 0, %ni
br i1 %cmp4, label %perf_nest_live_out_loop_i.lr.ph, label %for.end7
perf_nest_live_out_loop_i.lr.ph:
br label %perf_nest_live_out_loop_i
perf_nest_live_out_loop_i:
%x.addr.06 = phi i32 [ %x, %perf_nest_live_out_loop_i.lr.ph ], [ %x.addr.1.lcssa, %for.inc5 ]
%i.05 = phi i32 [ 0, %perf_nest_live_out_loop_i.lr.ph ], [ %inc6, %for.inc5 ]
%cmp21 = icmp slt i32 0, %nj
br i1 %cmp21, label %perf_nest_live_out_loop_j.lr.ph, label %for.inc5
perf_nest_live_out_loop_j.lr.ph:
br label %perf_nest_live_out_loop_j
perf_nest_live_out_loop_j:
%x.addr.13 = phi i32 [ %x.addr.06, %perf_nest_live_out_loop_j.lr.ph ], [ %add4, %perf_nest_live_out_loop_j ]
%j.02 = phi i32 [ 0, %perf_nest_live_out_loop_j.lr.ph ], [ %inc, %perf_nest_live_out_loop_j ]
%add = add nsw i32 %i.05, %j.02
%add4 = add nsw i32 %x.addr.13, %add
%inc = add nsw i32 %j.02, 1
%cmp2 = icmp slt i32 %inc, %nj
br i1 %cmp2, label %perf_nest_live_out_loop_j, label %for.cond1.for.inc5_crit_edge
for.cond1.for.inc5_crit_edge:
%split = phi i32 [ %add4, %perf_nest_live_out_loop_j ]
br label %for.inc5
for.inc5:
%x.addr.1.lcssa = phi i32 [ %split, %for.cond1.for.inc5_crit_edge ], [ %x.addr.06, %perf_nest_live_out_loop_i ]
%inc6 = add nsw i32 %i.05, 1
%cmp = icmp slt i32 %inc6, %ni
br i1 %cmp, label %perf_nest_live_out_loop_i, label %for.cond.for.end7_crit_edge
for.cond.for.end7_crit_edge:
%split7 = phi i32 [ %x.addr.1.lcssa, %for.inc5 ]
br label %for.end7
for.end7:
%x.addr.0.lcssa = phi i32 [ %split7, %for.cond.for.end7_crit_edge ], [ %x, %entry ]
ret i32 %x.addr.0.lcssa
}