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
73 lines
2.3 KiB
LLVM
73 lines
2.3 KiB
LLVM
; RUN: opt -basicaa -loop-versioning -S < %s | FileCheck %s
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target triple = "x86_64-unknown-linux-gnu"
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define void @fill(i8** %ls1.20, i8** %ls2.21, i8* %cse3.22) {
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; CHECK: bb1.lver.check:
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; CHECK: br i1 %memcheck.conflict, label %bb1.ph.lver.orig, label %bb1.ph
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bb1.ph:
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%ls1.20.promoted = load i8*, i8** %ls1.20
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%ls2.21.promoted = load i8*, i8** %ls2.21
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br label %bb1
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bb1:
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%_tmp302 = phi i8* [ %ls2.21.promoted, %bb1.ph ], [ %_tmp30, %bb1 ]
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%_tmp281 = phi i8* [ %ls1.20.promoted, %bb1.ph ], [ %_tmp28, %bb1 ]
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%_tmp14 = getelementptr i8, i8* %_tmp281, i16 -1
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%_tmp15 = load i8, i8* %_tmp14
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%add = add i8 %_tmp15, 1
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store i8 %add, i8* %_tmp281
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store i8 %add, i8* %_tmp302
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%_tmp28 = getelementptr i8, i8* %_tmp281, i16 1
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%_tmp30 = getelementptr i8, i8* %_tmp302, i16 1
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br i1 false, label %bb1, label %bb3.loopexit
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bb3.loopexit:
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%_tmp30.lcssa = phi i8* [ %_tmp30, %bb1 ]
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%_tmp15.lcssa = phi i8 [ %_tmp15, %bb1 ]
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%_tmp28.lcssa = phi i8* [ %_tmp28, %bb1 ]
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store i8* %_tmp28.lcssa, i8** %ls1.20
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store i8 %_tmp15.lcssa, i8* %cse3.22
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store i8* %_tmp30.lcssa, i8** %ls2.21
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br label %bb3
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bb3:
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ret void
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}
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define void @fill_no_null_opt(i8** %ls1.20, i8** %ls2.21, i8* %cse3.22) #0 {
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; CHECK-LABEL: fill_no_null_opt(
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; CHECK: bb1.lver.check:
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; CHECK: %lver.safe = or i1 %memcheck.conflict, %{{.*}}
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; CHECK: br i1 %lver.safe, label %bb1.ph.lver.orig, label %bb1.ph
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bb1.ph:
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%ls1.20.promoted = load i8*, i8** %ls1.20
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%ls2.21.promoted = load i8*, i8** %ls2.21
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br label %bb1
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bb1:
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%_tmp302 = phi i8* [ %ls2.21.promoted, %bb1.ph ], [ %_tmp30, %bb1 ]
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%_tmp281 = phi i8* [ %ls1.20.promoted, %bb1.ph ], [ %_tmp28, %bb1 ]
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%_tmp14 = getelementptr i8, i8* %_tmp281, i16 -1
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%_tmp15 = load i8, i8* %_tmp14
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%add = add i8 %_tmp15, 1
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store i8 %add, i8* %_tmp281
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store i8 %add, i8* %_tmp302
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%_tmp28 = getelementptr i8, i8* %_tmp281, i16 1
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%_tmp30 = getelementptr i8, i8* %_tmp302, i16 1
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br i1 false, label %bb1, label %bb3.loopexit
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bb3.loopexit:
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%_tmp30.lcssa = phi i8* [ %_tmp30, %bb1 ]
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%_tmp15.lcssa = phi i8 [ %_tmp15, %bb1 ]
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%_tmp28.lcssa = phi i8* [ %_tmp28, %bb1 ]
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store i8* %_tmp28.lcssa, i8** %ls1.20
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store i8 %_tmp15.lcssa, i8* %cse3.22
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store i8* %_tmp30.lcssa, i8** %ls2.21
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br label %bb3
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bb3:
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ret void
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}
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attributes #0 = { "null-pointer-is-valid"="true" }
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