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6a55f3d913
Current findBestLoopTop can find and move one kind of block to top, a latch block has one successor. Another common case is:
* a latch block
* it has two successors, one is loop header, another is exit
* it has more than one predecessors
If it is below one of its predecessors P, only P can fall through to it, all other predecessors need a jump to it, and another conditional jump to loop header. If it is moved before loop header, all its predecessors jump to it, then fall through to loop header. So all its predecessors except P can reduce one taken branch.
Differential Revision: https://reviews.llvm.org/D43256
llvm-svn: 363471
94 lines
3.3 KiB
LLVM
94 lines
3.3 KiB
LLVM
; RUN: llc -march=hexagon < %s | FileCheck %s
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; Make sure that the loop in the end has only one basic block.
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; CHECK-LABEL: fred
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; CHECK: %b2
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; Rely on the comments, make sure the one for the loop header is present.
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; CHECK: %loop
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; CHECK: %should_merge
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; CHECK: %exit
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target triple = "hexagon"
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define i32 @fred(i32 %a0, i64* nocapture readonly %a1) #0 {
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b2:
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%v3 = bitcast i64* %a1 to i32*
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%v4 = getelementptr inbounds i32, i32* %v3, i32 1
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%v5 = zext i32 %a0 to i64
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br label %loop
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loop: ; preds = %should_merge, %b2
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%v7 = phi i32 [ 0, %b2 ], [ %v49, %should_merge ]
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%v8 = phi i32 [ 0, %b2 ], [ %v42, %should_merge ]
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%v9 = phi i32* [ %v4, %b2 ], [ %v53, %should_merge ]
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%v10 = phi i32 [ 0, %b2 ], [ %v30, %should_merge ]
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%v11 = phi i32* [ %v3, %b2 ], [ %v51, %should_merge ]
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%v12 = phi i32 [ 0, %b2 ], [ %v23, %should_merge ]
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%v13 = phi i32 [ 2, %b2 ], [ %v54, %should_merge ]
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%v14 = load i32, i32* %v11, align 4, !tbaa !0
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%v15 = load i32, i32* %v9, align 4, !tbaa !0
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%v16 = icmp ult i32 %v13, 30
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%v17 = zext i32 %v12 to i64
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%v18 = shl nuw i64 %v17, 32
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%v19 = zext i32 %v14 to i64
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%v20 = or i64 %v18, %v19
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%v21 = tail call i64 @llvm.hexagon.A2.addp(i64 %v20, i64 %v5)
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%v22 = lshr i64 %v21, 32
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%v23 = trunc i64 %v22 to i32
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%v24 = zext i32 %v10 to i64
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%v25 = shl nuw i64 %v24, 32
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%v26 = zext i32 %v15 to i64
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%v27 = or i64 %v25, %v26
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%v28 = tail call i64 @llvm.hexagon.A2.addp(i64 %v27, i64 %v5)
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%v29 = lshr i64 %v28, 32
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%v30 = trunc i64 %v29 to i32
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%v31 = getelementptr inbounds i32, i32* %v3, i32 %v13
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%v32 = load i32, i32* %v31, align 4, !tbaa !0
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%v33 = or i32 %v13, 1
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%v34 = getelementptr inbounds i32, i32* %v3, i32 %v33
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%v35 = load i32, i32* %v34, align 4, !tbaa !0
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%v36 = zext i32 %v8 to i64
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%v37 = shl nuw i64 %v36, 32
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%v38 = zext i32 %v32 to i64
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%v39 = or i64 %v37, %v38
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%v40 = tail call i64 @llvm.hexagon.A2.subp(i64 %v39, i64 %v5)
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%v41 = lshr i64 %v40, 32
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%v42 = trunc i64 %v41 to i32
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%v43 = zext i32 %v7 to i64
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%v44 = shl nuw i64 %v43, 32
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%v45 = zext i32 %v35 to i64
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%v46 = or i64 %v44, %v45
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%v47 = tail call i64 @llvm.hexagon.A2.subp(i64 %v46, i64 %v5)
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%v48 = lshr i64 %v47, 32
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%v49 = trunc i64 %v48 to i32
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br i1 %v16, label %should_merge, label %exit
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should_merge: ; preds = %loop
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%v50 = add nuw nsw i32 %v13, 2
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%v51 = getelementptr inbounds i32, i32* %v3, i32 %v50
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%v52 = add nuw nsw i32 %v13, 3
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%v53 = getelementptr inbounds i32, i32* %v3, i32 %v52
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%v54 = add nuw nsw i32 %v13, 4
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br label %loop
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exit: ; preds = %loop
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%v57 = tail call i64 @llvm.hexagon.A2.combinew(i32 %v42, i32 %v23)
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%v58 = tail call i64 @llvm.hexagon.A2.combinew(i32 %v49, i32 %v30)
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%v59 = tail call i64 @llvm.hexagon.A2.addp(i64 %v57, i64 %v58)
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%v60 = lshr i64 %v59, 32
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%v61 = trunc i64 %v60 to i32
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ret i32 %v61
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}
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declare i64 @llvm.hexagon.A2.addp(i64, i64) #1
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declare i64 @llvm.hexagon.A2.subp(i64, i64) #1
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declare i64 @llvm.hexagon.A2.combinew(i32, i32) #1
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attributes #0 = { nounwind readonly "target-cpu"="hexagonv60" "target-features"="-hvx,-long-calls" }
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attributes #1 = { nounwind readnone }
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!0 = !{!1, !1, i64 0}
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!1 = !{!"long", !2, i64 0}
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!2 = !{!"omnipotent char", !3, i64 0}
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!3 = !{!"Simple C/C++ TBAA"}
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