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4a161bf875
Summary: Previously we would do this simplification only if it did not introduce any new truncs (excepting new truncs which replace other cast ops). This change weakens this condition: If the number of truncs stays the same, but we're able to transform trunc(X + Y) to X + trunc(Y), that's still simpler, and it may open up additional transformations. While we're here, also clean up some duplicated code. Reviewers: sanjoy Subscribers: hiraditya, llvm-commits Differential Revision: https://reviews.llvm.org/D48160 llvm-svn: 334736
46 lines
1.6 KiB
LLVM
46 lines
1.6 KiB
LLVM
; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
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; The initial SCEV for the backedge count is
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; (zext i2 {(trunc i32 (1 + %a1) to i2),+,1}<%b2> to i32).
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; In howFarToZero, this was further converted to an add-rec, the complexity
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; of which defeated the calculation of the backedge taken count.
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; Since such zero-extensions preserve the values being extended, strip
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; them in howFarToZero to simplify the input SCEV.
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; Check that the backedge taken count was actually computed:
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; CHECK: Determining loop execution counts for: @f0
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; CHECK-NEXT: Loop %b2: backedge-taken count is (-1 + (-1 * (trunc i32 %a1 to i2)))
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64"
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define i32 @f0(i32 %a0, i32 %a1, i32* nocapture %a2) #0 {
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b0:
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%v0 = and i32 %a1, 3
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%v1 = icmp eq i32 %v0, 0
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br i1 %v1, label %b4, label %b1
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b1: ; preds = %b0
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%v2 = shl i32 %a0, 7
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%v3 = add i32 %v2, -128
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br label %b2
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b2: ; preds = %b2, %b1
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%v4 = phi i32 [ %a1, %b1 ], [ %v9, %b2 ]
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%v5 = phi i32* [ %a2, %b1 ], [ %v8, %b2 ]
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%v6 = getelementptr inbounds i32, i32* %v5, i32 0
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store i32 %v3, i32* %v6, align 4
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%v8 = getelementptr inbounds i32, i32* %v5, i32 1
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%v9 = add nsw i32 %v4, 1
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%v10 = and i32 %v9, 3
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%v11 = icmp eq i32 %v10, 0
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br i1 %v11, label %b3, label %b2
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b3: ; preds = %b2
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br label %b4
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b4: ; preds = %b3, %b0
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ret i32 0
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}
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attributes #0 = { norecurse nounwind }
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