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647946fa14
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
87 lines
2.6 KiB
LLVM
87 lines
2.6 KiB
LLVM
; RUN: opt < %s -instcombine -S | FileCheck %s
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
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declare i32 @__gxx_personality_v0(...)
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declare void @__cxa_call_unexpected(i8*)
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declare i64 @llvm.objectsize.i64(i8*, i1) nounwind readonly
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declare i8* @_Znwm(i64)
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; CHECK-LABEL: @f1(
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define i64 @f1() nounwind uwtable ssp personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
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entry:
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; CHECK: nvoke noalias i8* undef()
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%call = invoke noalias i8* undef()
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to label %invoke.cont unwind label %lpad
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invoke.cont:
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; CHECK: ret i64 0
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%0 = tail call i64 @llvm.objectsize.i64(i8* %call, i1 false)
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ret i64 %0
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lpad:
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%1 = landingpad { i8*, i32 }
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filter [0 x i8*] zeroinitializer
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%2 = extractvalue { i8*, i32 } %1, 0
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tail call void @__cxa_call_unexpected(i8* %2) noreturn nounwind
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unreachable
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}
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; CHECK-LABEL: @f2(
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define i64 @f2() nounwind uwtable ssp personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
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entry:
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; CHECK: nvoke noalias i8* null()
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%call = invoke noalias i8* null()
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to label %invoke.cont unwind label %lpad
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invoke.cont:
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; CHECK: ret i64 0
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%0 = tail call i64 @llvm.objectsize.i64(i8* %call, i1 false)
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ret i64 %0
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lpad:
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%1 = landingpad { i8*, i32 }
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filter [0 x i8*] zeroinitializer
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%2 = extractvalue { i8*, i32 } %1, 0
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tail call void @__cxa_call_unexpected(i8* %2) noreturn nounwind
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unreachable
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}
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; CHECK-LABEL: @f2_no_null_opt(
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define i64 @f2_no_null_opt() nounwind uwtable ssp #0 personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
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entry:
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; CHECK: invoke noalias i8* null()
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%call = invoke noalias i8* null()
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to label %invoke.cont unwind label %lpad
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invoke.cont:
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; CHECK: call i64 @llvm.objectsize.i64.p0i8(i8* %call, i1 false, i1 false)
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%0 = tail call i64 @llvm.objectsize.i64(i8* %call, i1 false)
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ret i64 %0
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lpad:
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%1 = landingpad { i8*, i32 }
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filter [0 x i8*] zeroinitializer
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%2 = extractvalue { i8*, i32 } %1, 0
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tail call void @__cxa_call_unexpected(i8* %2) noreturn nounwind
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unreachable
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}
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attributes #0 = { "null-pointer-is-valid"="true" }
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; CHECK-LABEL: @f3(
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define void @f3() nounwind uwtable ssp personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
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; CHECK: invoke void @llvm.donothing()
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%call = invoke noalias i8* @_Znwm(i64 13)
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to label %invoke.cont unwind label %lpad
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invoke.cont:
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ret void
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lpad:
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%1 = landingpad { i8*, i32 }
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filter [0 x i8*] zeroinitializer
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%2 = extractvalue { i8*, i32 } %1, 0
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tail call void @__cxa_call_unexpected(i8* %2) noreturn nounwind
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unreachable
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}
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