b69919b537
GVN Load PRE can split the backedge causing breaking the loop structure where the latch contains the conditional branch with for example induction variable. Different optimizations expect this form of the loop, so it is better to preserve it for some time. This CL adds an option to control an ability to split backedge. Default value is true so technically it is NFC and current behavior is not changed. Reviewers: fedor.sergeev, mkazantsev, nikic, reames, fhahn Reviewed By: mkazasntsev Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D89854
58 lines
2.2 KiB
LLVM
58 lines
2.2 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -S -basic-aa -gvn -enable-split-backedge-in-load-pre=true < %s | FileCheck %s --check-prefix=ON
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; RUN: opt -S -basic-aa -gvn -enable-split-backedge-in-load-pre=false < %s | FileCheck %s --check-prefix=OFF
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target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32"
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define i32 @test(i1 %b, i1 %c, i32* noalias %p, i32* noalias %q) {
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; ON-LABEL: @test(
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; ON-NEXT: entry:
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; ON-NEXT: [[Y1:%.*]] = load i32, i32* [[P:%.*]], align 4
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; ON-NEXT: call void @use(i32 [[Y1]])
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; ON-NEXT: br label [[HEADER:%.*]]
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; ON: header:
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; ON-NEXT: [[Y:%.*]] = phi i32 [ [[Y_PRE:%.*]], [[SKIP_HEADER_CRIT_EDGE:%.*]] ], [ [[Y]], [[HEADER]] ], [ [[Y1]], [[ENTRY:%.*]] ]
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; ON-NEXT: call void @use(i32 [[Y]])
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; ON-NEXT: br i1 [[B:%.*]], label [[SKIP:%.*]], label [[HEADER]]
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; ON: skip:
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; ON-NEXT: call void @clobber(i32* [[P]], i32* [[Q:%.*]])
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; ON-NEXT: br i1 [[C:%.*]], label [[SKIP_HEADER_CRIT_EDGE]], label [[EXIT:%.*]]
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; ON: skip.header_crit_edge:
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; ON-NEXT: [[Y_PRE]] = load i32, i32* [[P]], align 4
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; ON-NEXT: br label [[HEADER]]
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; ON: exit:
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; ON-NEXT: ret i32 [[Y]]
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;
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; OFF-LABEL: @test(
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; OFF-NEXT: entry:
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; OFF-NEXT: [[Y1:%.*]] = load i32, i32* [[P:%.*]], align 4
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; OFF-NEXT: call void @use(i32 [[Y1]])
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; OFF-NEXT: br label [[HEADER:%.*]]
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; OFF: header:
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; OFF-NEXT: [[Y:%.*]] = load i32, i32* [[P]], align 4
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; OFF-NEXT: call void @use(i32 [[Y]])
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; OFF-NEXT: br i1 [[B:%.*]], label [[SKIP:%.*]], label [[HEADER]]
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; OFF: skip:
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; OFF-NEXT: call void @clobber(i32* [[P]], i32* [[Q:%.*]])
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; OFF-NEXT: br i1 [[C:%.*]], label [[HEADER]], label [[EXIT:%.*]]
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; OFF: exit:
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; OFF-NEXT: ret i32 [[Y]]
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;
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entry:
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%y1 = load i32, i32* %p
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call void @use(i32 %y1)
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br label %header
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header:
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%y = load i32, i32* %p
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call void @use(i32 %y)
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br i1 %b, label %skip, label %header
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skip:
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call void @clobber(i32* %p, i32* %q)
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br i1 %c, label %header, label %exit
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exit:
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ret i32 %y
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}
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declare void @use(i32) readonly
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declare void @clobber(i32* %p, i32* %q)
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