77eeac3d9e
Summary: Support for this option is needed for building Linux kernel. This is a very frequently requested feature by kernel developers. More details : https://lkml.org/lkml/2018/4/4/601 GCC option description for -fdelete-null-pointer-checks: This Assume that programs cannot safely dereference null pointers, and that no code or data element resides at address zero. -fno-delete-null-pointer-checks is the inverse of this implying that null pointer dereferencing is not undefined. This feature is implemented in LLVM IR in this CL as the function attribute "null-pointer-is-valid"="true" in IR (Under review at D47894). The CL updates several passes that assumed null pointer dereferencing is undefined to not optimize when the "null-pointer-is-valid"="true" attribute is present. Reviewers: t.p.northover, efriedma, jyknight, chandlerc, rnk, srhines, void, george.burgess.iv Reviewed By: efriedma, george.burgess.iv Subscribers: eraman, haicheng, george.burgess.iv, drinkcat, theraven, reames, sanjoy, xbolva00, llvm-commits Differential Revision: https://reviews.llvm.org/D47895 llvm-svn: 336613
240 lines
7.5 KiB
LLVM
240 lines
7.5 KiB
LLVM
; RUN: opt -simplifycfg -S < %s | FileCheck %s
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declare void @bar() nounwind
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define i32 @test1(i32* %a, i32 %b, i32* %c, i32 %d) nounwind {
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entry:
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%tobool = icmp eq i32 %b, 0
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br i1 %tobool, label %if.else, label %if.then
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if.then: ; preds = %entry
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tail call void @bar() nounwind
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br label %if.end7
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if.else: ; preds = %entry
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%tobool3 = icmp eq i32 %d, 0
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br i1 %tobool3, label %if.end7, label %if.then4
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if.then4: ; preds = %if.else
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tail call void @bar() nounwind
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br label %if.end7
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if.end7: ; preds = %if.else, %if.then4, %if.then
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%x.0 = phi i32* [ %a, %if.then ], [ %c, %if.then4 ], [ null, %if.else ]
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%tmp9 = load i32, i32* %x.0
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ret i32 %tmp9
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; CHECK-LABEL: @test1(
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; CHECK: if.else:
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; CHECK: br label %if.end7
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; CHECK: phi i32* [ %a, %if.then ], [ %c, %if.else ]
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}
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define i32 @test1_no_null_opt(i32* %a, i32 %b, i32* %c, i32 %d) nounwind #0 {
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entry:
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%tobool = icmp eq i32 %b, 0
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br i1 %tobool, label %if.else, label %if.then
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if.then: ; preds = %entry
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tail call void @bar() nounwind
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br label %if.end7
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if.else: ; preds = %entry
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%tobool3 = icmp eq i32 %d, 0
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br i1 %tobool3, label %if.end7, label %if.then4
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if.then4: ; preds = %if.else
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tail call void @bar() nounwind
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br label %if.end7
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if.end7: ; preds = %if.else, %if.then4, %if.then
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%x.0 = phi i32* [ %a, %if.then ], [ %c, %if.then4 ], [ null, %if.else ]
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%tmp9 = load i32, i32* %x.0
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ret i32 %tmp9
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; CHECK-LABEL: @test1_no_null_opt(
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; CHECK: if.then:
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; CHECK: if.else:
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; CHECK: if.then4:
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; CHECK: br label %if.end7
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; CHECK: if.end7:
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; CHECK-NEXT: phi i32* [ %a, %if.then ], [ %c, %if.then4 ], [ null, %if.else ]
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}
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define i32 @test2(i32* %a, i32 %b, i32* %c, i32 %d) nounwind {
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entry:
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%tobool = icmp eq i32 %b, 0
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br i1 %tobool, label %if.else, label %if.then
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if.then: ; preds = %entry
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tail call void @bar() nounwind
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br label %if.end7
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if.else: ; preds = %entry
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%tobool3 = icmp eq i32 %d, 0
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br i1 %tobool3, label %if.end7, label %if.then4
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if.then4: ; preds = %if.else
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tail call void @bar() nounwind
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br label %if.end7
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if.end7: ; preds = %if.else, %if.then4, %if.then
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%x.0 = phi i32* [ %a, %if.then ], [ null, %if.then4 ], [ null, %if.else ]
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%tmp9 = load i32, i32* %x.0
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ret i32 %tmp9
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; CHECK-LABEL: @test2(
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; CHECK: if.else:
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; CHECK: unreachable
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; CHECK-NOT: phi
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}
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define i32 @test2_no_null_opt(i32* %a, i32 %b, i32* %c, i32 %d) nounwind #0 {
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entry:
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%tobool = icmp eq i32 %b, 0
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br i1 %tobool, label %if.else, label %if.then
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if.then: ; preds = %entry
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tail call void @bar() nounwind
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br label %if.end7
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if.else: ; preds = %entry
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%tobool3 = icmp eq i32 %d, 0
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br i1 %tobool3, label %if.end7, label %if.then4
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if.then4: ; preds = %if.else
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tail call void @bar() nounwind
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br label %if.end7
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if.end7: ; preds = %if.else, %if.then4, %if.then
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%x.0 = phi i32* [ %a, %if.then ], [ null, %if.then4 ], [ null, %if.else ]
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%tmp9 = load i32, i32* %x.0
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ret i32 %tmp9
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; CHECK-LABEL: @test2_no_null_opt(
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; CHECK: if.then:
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; CHECK: if.else:
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; CHECK: if.then4:
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; CHECK: if.end7:
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; CHECK-NEXT: phi i32* [ %a, %if.then ], [ null, %if.then4 ], [ null, %if.else ]
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}
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define i32 @test3(i32* %a, i32 %b, i32* %c, i32 %d) nounwind {
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entry:
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%tobool = icmp eq i32 %b, 0
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br i1 %tobool, label %if.else, label %if.then
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if.then: ; preds = %entry
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tail call void @bar() nounwind
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br label %if.end7
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if.else: ; preds = %entry
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%tobool3 = icmp eq i32 %d, 0
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br i1 %tobool3, label %if.end7, label %if.then4
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if.then4: ; preds = %if.else
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tail call void @bar() nounwind
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br label %if.end7
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if.end7: ; preds = %if.else, %if.then4, %if.then
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%x.0 = phi i32* [ %a, %if.then ], [ null, %if.then4 ], [ null, %if.else ]
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tail call void @bar() nounwind
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%tmp9 = load i32, i32* %x.0
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ret i32 %tmp9
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; CHECK-LABEL: @test3(
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; CHECK: if.end7:
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; CHECK: phi i32* [ %a, %if.then ], [ null, %if.then4 ], [ null, %if.else ]
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}
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define i32 @test3_no_null_opt(i32* %a, i32 %b, i32* %c, i32 %d) nounwind #0 {
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entry:
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%tobool = icmp eq i32 %b, 0
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br i1 %tobool, label %if.else, label %if.then
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if.then: ; preds = %entry
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tail call void @bar() nounwind
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br label %if.end7
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if.else: ; preds = %entry
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%tobool3 = icmp eq i32 %d, 0
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br i1 %tobool3, label %if.end7, label %if.then4
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if.then4: ; preds = %if.else
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tail call void @bar() nounwind
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br label %if.end7
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if.end7: ; preds = %if.else, %if.then4, %if.then
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%x.0 = phi i32* [ %a, %if.then ], [ null, %if.then4 ], [ null, %if.else ]
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tail call void @bar() nounwind
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%tmp9 = load i32, i32* %x.0
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ret i32 %tmp9
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; CHECK-LABEL: @test3_no_null_opt(
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; CHECK: if.then:
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; CHECK: if.else:
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; CHECK: if.then4:
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; CHECK: if.end7:
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; CHECK-NEXT: phi i32* [ %a, %if.then ], [ null, %if.then4 ], [ null, %if.else ]
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}
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define i32 @test4(i32* %a, i32 %b, i32* %c, i32 %d) nounwind {
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entry:
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%tobool = icmp eq i32 %b, 0
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br i1 %tobool, label %if.else, label %if.then
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if.then: ; preds = %entry
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tail call void @bar() nounwind
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br label %if.end7
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if.else: ; preds = %entry
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%tobool3 = icmp eq i32 %d, 0
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br i1 %tobool3, label %if.end7, label %if.then4
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if.then4: ; preds = %if.else
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tail call void @bar() nounwind
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br label %if.end7
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if.end7: ; preds = %if.else, %if.then4, %if.then
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%x.0 = phi i32* [ %a, %if.then ], [ null, %if.then4 ], [ null, %if.else ]
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%gep = getelementptr i32, i32* %x.0, i32 10
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%tmp9 = load i32, i32* %gep
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%tmp10 = or i32 %tmp9, 1
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store i32 %tmp10, i32* %gep
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ret i32 %tmp9
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; CHECK-LABEL: @test4(
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; CHECK-NOT: phi
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}
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define i32 @test4_no_null_opt(i32* %a, i32 %b, i32* %c, i32 %d) nounwind #0 {
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entry:
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%tobool = icmp eq i32 %b, 0
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br i1 %tobool, label %if.else, label %if.then
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if.then: ; preds = %entry
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tail call void @bar() nounwind
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br label %if.end7
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if.else: ; preds = %entry
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%tobool3 = icmp eq i32 %d, 0
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br i1 %tobool3, label %if.end7, label %if.then4
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if.then4: ; preds = %if.else
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tail call void @bar() nounwind
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br label %if.end7
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if.end7: ; preds = %if.else, %if.then4, %if.then
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%x.0 = phi i32* [ %a, %if.then ], [ null, %if.then4 ], [ null, %if.else ]
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%gep = getelementptr i32, i32* %x.0, i32 10
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%tmp9 = load i32, i32* %gep
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%tmp10 = or i32 %tmp9, 1
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store i32 %tmp10, i32* %gep
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ret i32 %tmp9
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; CHECK-LABEL: @test4_no_null_opt(
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; CHECK: if.then:
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; CHECK: if.else:
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; CHECK: if.then4:
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; CHECK: if.end7:
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; CHECK-NEXT: phi i32* [ %a, %if.then ], [ null, %if.then4 ], [ null, %if.else ]
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}
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attributes #0 = { "null-pointer-is-valid"="true" }
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