0a5d52a757
This patch implements getCFInstrCost TTI hook that mostly affects LoopVectorizer decisions. It sets zero cost for PHI nodes and zero throughput cost for branches (assuming that branches are likely to be predicted). The implementation is similar to X86/AArch64/PowerPC targets and reduces loop cost by excluding induction PHIs/loop latch branches, which in turn leads to selecting smaller vectorization factor.
35 lines
1.5 KiB
LLVM
35 lines
1.5 KiB
LLVM
; REQUIRES: asserts
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; RUN: opt < %s -passes=loop-vectorize -mtriple riscv64 -riscv-v-vector-bits-min=128 -mattr="+v" -debug-only=loop-vectorize -S 2>&1 | FileCheck %s
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; CHECK: LV: Loop hints: force=enabled
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; CHECK: LV: Scalar loop costs: 4.
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; ChosenFactor.Cost is 4, but the real cost will be divided by the width, which is 2.
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; CHECK: LV: Vector loop of width 2 costs: 2.
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; Regardless of force vectorization or not, this loop will eventually be vectorized because of the cost model.
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; Therefore, the following message does not need to be printed even if vectorization is explicitly forced in the metadata.
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; CHECK-NOT: LV: Vectorization seems to be not beneficial, but was forced by a user.
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target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n64-S128"
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target triple = "riscv64-unknown-unknown"
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define i64 @foo(ptr nocapture noundef readonly %a, i64 noundef %N, i64 noundef %init) {
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entry:
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br label %for.body
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for.body: ; preds = %entry, %for.body
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%i.06 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
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%rd.05 = phi i64 [ %add, %for.body ], [ %init, %entry ]
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%arrayidx = getelementptr inbounds i64, ptr %a, i64 %i.06
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%0 = load i64, ptr %arrayidx, align 8
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%add = add nsw i64 %0, %rd.05
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%inc = add nuw i64 %i.06, 1
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%exitcond.not = icmp eq i64 %inc, %N
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br i1 %exitcond.not, label %for.end, label %for.body, !llvm.loop !0
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for.end: ; preds = %for.body
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ret i64 %add
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}
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!0 = !{!0, !1}
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!1 = !{!"llvm.loop.vectorize.enable", i1 true}
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