29d054bf12
This improvement adds "assume" after removal of branch basing on UB in successor block. Consider the following example: ``` pred: x = ... cond = x > 10 br cond, bb, other.succ bb: phi [nullptr, pred], ... // other possible preds load(phi) // UB if we came from pred other.succ: // here we know that x <= 10, but this knowledge is lost // after the branch is turned to unconditional unless we // preserve it with assume. ``` If we remove the branch basing on knowledge about UB in a successor block, then the fact that x <= 10 is other.succ might be lost if this condition is not inferrable from any dominating condition. To preserve this knowledge, we can add assume intrinsic with (possibly inverted) branch condition. Patch by Dmitry Bakunevich! Differential Revision: https://reviews.llvm.org/D109054 Reviewed By: lebedev.ri
68 lines
2.3 KiB
LLVM
68 lines
2.3 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 -S | FileCheck %s
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%0 = type { %1*, %2* }
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%1 = type { %0* }
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%2 = type { %0*, %2* }
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define void @eggs(i1 %arg, i1 %arg16, %0* %arg17, %0* %arg18, %0* %arg19) {
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; CHECK-LABEL: @eggs(
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; CHECK-NEXT: bb:
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; CHECK-NEXT: br i1 [[ARG:%.*]], label [[BB20:%.*]], label [[BB21:%.*]]
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; CHECK: bb20:
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; CHECK-NEXT: call void @wombat()
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; CHECK-NEXT: unreachable
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; CHECK: bb21:
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; CHECK-NEXT: [[I:%.*]] = icmp eq %0* [[ARG17:%.*]], null
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; CHECK-NEXT: [[TMP0:%.*]] = xor i1 [[I]], true
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; CHECK-NEXT: call void @llvm.assume(i1 [[TMP0]])
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; CHECK-NEXT: call void @hoge()
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; CHECK-NEXT: [[TMP1:%.*]] = xor i1 [[ARG16:%.*]], true
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; CHECK-NEXT: call void @llvm.assume(i1 [[TMP1]])
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; CHECK-NEXT: [[I27:%.*]] = getelementptr inbounds [[TMP0]], %0* [[ARG19:%.*]], i64 0, i32 0
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; CHECK-NEXT: [[I28:%.*]] = load %1*, %1** [[I27]], align 8
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; CHECK-NEXT: call void @pluto.1(%1* [[I28]])
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; CHECK-NEXT: call void @pluto()
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; CHECK-NEXT: ret void
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;
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bb:
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br i1 %arg, label %bb20, label %bb21
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bb20: ; preds = %bb
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call void @wombat()
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br label %bb24
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bb21: ; preds = %bb
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%i = icmp eq %0* %arg17, null
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br i1 %i, label %bb24, label %bb22
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bb22: ; preds = %bb21
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call void @hoge()
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br i1 %arg16, label %bb24, label %bb23
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bb23: ; preds = %bb22
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br label %bb24
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bb24: ; preds = %bb23, %bb22, %bb21, %bb20
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%i25 = phi i1 [ false, %bb21 ], [ false, %bb20 ], [ false, %bb23 ], [ false, %bb22 ]
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%i26 = phi %0* [ null, %bb21 ], [ null, %bb20 ], [ %arg19, %bb23 ], [ null, %bb22 ]
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%i27 = getelementptr inbounds %0, %0* %i26, i64 0, i32 0
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%i28 = load %1*, %1** %i27, align 8
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call void @pluto.1(%1* %i28)
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br i1 %i25, label %bb30, label %bb29
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bb29: ; preds = %bb24
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call void @pluto()
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ret void
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bb30: ; preds = %bb24
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call void @spam()
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ret void
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}
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declare void @wombat()
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declare void @pluto()
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declare void @spam()
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declare void @hoge()
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declare void @pluto.1(%1*)
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