llvm: Add support for "-fno-delete-null-pointer-checks"
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
diff --git a/llvm/test/Transforms/Inline/attributes.ll b/llvm/test/Transforms/Inline/attributes.ll
index 0df3cfa..c2808ba 100644
--- a/llvm/test/Transforms/Inline/attributes.ll
+++ b/llvm/test/Transforms/Inline/attributes.ll
@@ -333,6 +333,50 @@
; CHECK-NEXT: ret i32
}
+; Calle with "null-pointer-is-valid"="true" attribute should not be inlined
+; into a caller without this attribute. Exception: alwaysinline callee
+; can still be inlined.
+
+define i32 @null-pointer-is-valid_callee0(i32 %i) "null-pointer-is-valid"="true" {
+ ret i32 %i
+; CHECK: @null-pointer-is-valid_callee0(i32 %i)
+; CHECK-NEXT: ret i32
+}
+
+define i32 @null-pointer-is-valid_callee1(i32 %i) alwaysinline "null-pointer-is-valid"="true" {
+ ret i32 %i
+; CHECK: @null-pointer-is-valid_callee1(i32 %i)
+; CHECK-NEXT: ret i32
+}
+
+define i32 @null-pointer-is-valid_callee2(i32 %i) {
+ ret i32 %i
+; CHECK: @null-pointer-is-valid_callee2(i32 %i)
+; CHECK-NEXT: ret i32
+}
+
+define i32 @test_null-pointer-is-valid0(i32 %i) {
+ %1 = call i32 @null-pointer-is-valid_callee0(i32 %i)
+ ret i32 %1
+; CHECK: @test_null-pointer-is-valid0(
+; CHECK: call i32 @null-pointer-is-valid_callee0
+; CHECK-NEXT: ret i32
+}
+
+define i32 @test_null-pointer-is-valid1(i32 %i) {
+ %1 = call i32 @null-pointer-is-valid_callee1(i32 %i)
+ ret i32 %1
+; CHECK: @test_null-pointer-is-valid1(
+; CHECK-NEXT: ret i32
+}
+
+define i32 @test_null-pointer-is-valid2(i32 %i) "null-pointer-is-valid"="true" {
+ %1 = call i32 @null-pointer-is-valid_callee2(i32 %i)
+ ret i32 %1
+; CHECK: @test_null-pointer-is-valid2(
+; CHECK-NEXT: ret i32
+}
+
; CHECK: attributes [[FPMAD_FALSE]] = { "less-precise-fpmad"="false" }
; CHECK: attributes [[FPMAD_TRUE]] = { "less-precise-fpmad"="true" }
; CHECK: attributes [[NOIMPLICITFLOAT]] = { noimplicitfloat }