c7b25e4359
We'd added support a while back from breaking the backedge if SCEV can prove the trip count is zero. However, we used the exact trip count which requires *all* exits be analyzeable. I noticed while writing test cases for another patch that this disallows cases where one exit is provably taken paired with another which is unknown. This patch adds the upper bound case. We could use a symbolic max trip count here instead, but we use an isKnownNonZero filter (presumably for compile time?) for the first-iteration reasoning. I decided this was a more obvious incremental step, and we could go back and untangle the schemes separately. Differential Revision: https://reviews.llvm.org/D108833
79 lines
1.9 KiB
LLVM
79 lines
1.9 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -loop-deletion -verify-loop-info -S | FileCheck %s
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target triple = "x86_64-unknown-linux-gnu"
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@G = external global i32
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define void @func_1() {
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; CHECK-LABEL: @func_1(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LBL_2368:%.*]]
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; CHECK: lbl_2368:
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; CHECK-NEXT: [[CMP289:%.*]] = icmp slt i32 undef, -5
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; CHECK-NEXT: br i1 [[CMP289]], label [[CLEANUP967:%.*]], label [[UNREACHABLE:%.*]]
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; CHECK: cleanup967:
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; CHECK-NEXT: switch i32 undef, label [[CLEANUP1169:%.*]] [
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; CHECK-NEXT: i32 20, label [[CLEANUP967_LBL_2368_CRIT_EDGE:%.*]]
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; CHECK-NEXT: ]
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; CHECK: cleanup967.lbl_2368_crit_edge:
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; CHECK-NEXT: unreachable
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; CHECK: cleanup1169:
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; CHECK-NEXT: ret void
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; CHECK: unreachable:
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; CHECK-NEXT: unreachable
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;
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entry:
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br label %lbl_2368
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lbl_2368:
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%cmp289 = icmp slt i32 undef, -5
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br i1 %cmp289, label %cleanup967, label %unreachable
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cleanup967:
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switch i32 undef, label %cleanup1169 [
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i32 20, label %lbl_2368
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]
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cleanup1169:
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ret void
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unreachable:
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unreachable
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}
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define void @func_2() {
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; CHECK-LABEL: @func_2(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[LBL_2368:%.*]]
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; CHECK: lbl_2368:
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; CHECK-NEXT: br i1 false, label [[CLEANUP967:%.*]], label [[UNREACHABLE:%.*]]
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; CHECK: cleanup967:
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; CHECK-NEXT: switch i32 undef, label [[CLEANUP1169:%.*]] [
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; CHECK-NEXT: i32 20, label [[CLEANUP967_LBL_2368_CRIT_EDGE:%.*]]
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; CHECK-NEXT: ]
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; CHECK: cleanup967.lbl_2368_crit_edge:
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; CHECK-NEXT: unreachable
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; CHECK: cleanup1169:
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; CHECK-NEXT: ret void
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; CHECK: unreachable:
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; CHECK-NEXT: unreachable
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;
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entry:
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br label %lbl_2368
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lbl_2368:
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br i1 false, label %cleanup967, label %unreachable
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cleanup967:
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switch i32 undef, label %cleanup1169 [
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i32 20, label %lbl_2368
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]
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cleanup1169:
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ret void
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unreachable:
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unreachable
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}
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