371fcb720e
That transformation is lossy, as discussed in https://github.com/llvm/llvm-project/issues/53853 and https://github.com/rust-lang/rust/issues/85133#issuecomment-904185574 This is an alternative to D119839, which would add a limited IPSCCP into SimplifyCFG. Unlike lowering switch to lookup, we still want this transformation to happen relatively early, but after giving a chance for the things like CVP to do their thing. It seems like deferring it just until the IPSCCP is enough for the tests at hand, but perhaps we need to be more aggressive and disable it until CVP. Fixes https://github.com/llvm/llvm-project/issues/53853 Refs. https://github.com/rust-lang/rust/issues/85133 Reviewed By: nikic Differential Revision: https://reviews.llvm.org/D119854
42 lines
1.2 KiB
LLVM
42 lines
1.2 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -switch-range-to-icmp -S | FileCheck %s
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; Check that simplifycfg deletes a dead 'seteq' instruction when it
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; folds a conditional branch into a switch instruction.
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declare void @foo()
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declare void @bar()
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define void @testcfg(i32 %V) {
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; CHECK-LABEL: @testcfg(
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; CHECK-NEXT: [[V_OFF:%.*]] = add i32 [[V:%.*]], -15
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; CHECK-NEXT: [[SWITCH:%.*]] = icmp ult i32 [[V_OFF]], 2
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; CHECK-NEXT: br i1 [[SWITCH]], label [[L2:%.*]], label [[L1:%.*]]
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; CHECK: common.ret:
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; CHECK-NEXT: ret void
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; CHECK: L1:
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; CHECK-NEXT: call void @foo()
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; CHECK-NEXT: br label [[COMMON_RET:%.*]]
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; CHECK: L2:
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; CHECK-NEXT: call void @bar()
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; CHECK-NEXT: br label [[COMMON_RET]]
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;
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%C = icmp eq i32 %V, 18
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%D = icmp eq i32 %V, 180
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%E = or i1 %C, %D
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br i1 %E, label %L1, label %Sw
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Sw: ; preds = %0
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switch i32 %V, label %L1 [
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i32 15, label %L2
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i32 16, label %L2
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]
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L1: ; preds = %Sw, %0
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call void @foo( )
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ret void
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L2: ; preds = %Sw, %Sw
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call void @bar( )
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ret void
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}
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