mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2025-01-31 20:51:52 +01:00
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
29 lines
722 B
LLVM
29 lines
722 B
LLVM
; RUN: opt < %s -globalopt -S | FileCheck %s
|
|
|
|
@a = internal global i64* null, align 8
|
|
; CHECK: @a
|
|
|
|
; PR13968
|
|
define void @qux_no_null_opt() nounwind #0 {
|
|
; CHECK-LABEL: @qux_no_null_opt(
|
|
; CHECK: getelementptr i64*, i64** @a, i32 1
|
|
; CHECK: store i64* inttoptr (i64 1 to i64*), i64** @a
|
|
%b = bitcast i64** @a to i8*
|
|
%g = getelementptr i64*, i64** @a, i32 1
|
|
%cmp = icmp ne i8* null, %b
|
|
%cmp2 = icmp eq i8* null, %b
|
|
%cmp3 = icmp eq i64** null, %g
|
|
store i64* inttoptr (i64 1 to i64*), i64** @a, align 8
|
|
%l = load i64*, i64** @a, align 8
|
|
ret void
|
|
}
|
|
|
|
define i64* @bar() {
|
|
%X = load i64*, i64** @a, align 8
|
|
ret i64* %X
|
|
; CHECK-LABEL: @bar(
|
|
; CHECK: load
|
|
}
|
|
|
|
attributes #0 = { "null-pointer-is-valid"="true" }
|