a3c964a278
When folding tail, branch taken count is computed during initial VPlan execution and recorded to be used by the compare computing the loop's mask. This recording should directly set the State, instead of reusing Value2VPValue mapping which serves original Values present prior to vectorization. The branch taken count may be a constant Value, which may be used elsewhere in the loop; trying to employ Value2VPValue for both leads to the issue reported in https://reviews.llvm.org/D76992#inline-721028 Differential Revision: https://reviews.llvm.org/D78847
75 lines
2.5 KiB
LLVM
75 lines
2.5 KiB
LLVM
; RUN: opt < %s -loop-vectorize -prefer-predicate-over-epilog -force-vector-width=4 -S | FileCheck %s
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; Check that a counting-down loop which has no primary induction variable
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; is vectorized with preferred predication.
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; CHECK-LABEL: vector.body:
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; CHECK-LABEL: middle.block:
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; CHECK-NEXT: br i1 true,
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target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
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define dso_local void @foo(i8* noalias nocapture readonly %A, i8* noalias nocapture readonly %B, i8* noalias nocapture %C, i32 %N) {
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entry:
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%cmp6 = icmp eq i32 %N, 0
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br i1 %cmp6, label %while.end, label %while.body.preheader
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while.body.preheader:
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br label %while.body
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while.body:
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%N.addr.010 = phi i32 [ %dec, %while.body ], [ %N, %while.body.preheader ]
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%C.addr.09 = phi i8* [ %incdec.ptr4, %while.body ], [ %C, %while.body.preheader ]
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%B.addr.08 = phi i8* [ %incdec.ptr1, %while.body ], [ %B, %while.body.preheader ]
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%A.addr.07 = phi i8* [ %incdec.ptr, %while.body ], [ %A, %while.body.preheader ]
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%incdec.ptr = getelementptr inbounds i8, i8* %A.addr.07, i32 1
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%0 = load i8, i8* %A.addr.07, align 1
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%incdec.ptr1 = getelementptr inbounds i8, i8* %B.addr.08, i32 1
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%1 = load i8, i8* %B.addr.08, align 1
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%add = add i8 %1, %0
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%incdec.ptr4 = getelementptr inbounds i8, i8* %C.addr.09, i32 1
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store i8 %add, i8* %C.addr.09, align 1
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%dec = add i32 %N.addr.010, -1
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%cmp = icmp eq i32 %dec, 0
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br i1 %cmp, label %while.end.loopexit, label %while.body
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while.end.loopexit:
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br label %while.end
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while.end:
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ret void
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}
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; Make sure a loop is successfully vectorized with fold-tail when the backedge
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; taken count is constant and used inside the loop. Issue revealed by D76992.
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;
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define void @reuse_const_btc(i8* %A) optsize {
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; CHECK-LABEL: @reuse_const_btc
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; CHECK: {{%.*}} = icmp ule <4 x i32> {{%.*}}, <i32 13, i32 13, i32 13, i32 13>
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; CHECK: {{%.*}} = select <4 x i1> {{%.*}}, <4 x i32> <i32 12, i32 12, i32 12, i32 12>, <4 x i32> <i32 13, i32 13, i32 13, i32 13>
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;
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entry:
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br label %loop
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loop:
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%riv = phi i32 [ 13, %entry ], [ %rivMinus1, %merge ]
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%sub = sub nuw nsw i32 20, %riv
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%arrayidx = getelementptr inbounds i8, i8* %A, i32 %sub
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%cond0 = icmp eq i32 %riv, 7
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br i1 %cond0, label %then, label %else
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then:
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br label %merge
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else:
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br label %merge
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merge:
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%blend = phi i32 [ 13, %then ], [ 12, %else ]
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%trunc = trunc i32 %blend to i8
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store i8 %trunc, i8* %arrayidx, align 1
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%rivMinus1 = add nuw nsw i32 %riv, -1
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%cond = icmp eq i32 %riv, 0
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br i1 %cond, label %exit, label %loop
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exit:
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ret void
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}
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