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llvm-project/llvm/test/Analysis/BasicAA/gep-decomposition-limit.ll

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[BasicAA] Add test for decomposition limit (NFC) Test behavior before/at/after the GEP decomposition limit.
2020-11-10 03:42:57 +08:00
; RUN: opt -S -basic-aa -aa-eval -print-all-alias-modref-info -disable-output < %s 2>&1 | FileCheck %s
; CHECK-LABEL: Function: test
;; Before limit:
; CHECK-DAG: MustAlias: i8* %gep.add5, i8* %gep.inc5
; CHECK-DAG: NoAlias: i8* %gep.inc3, i8* %gep.inc5
; CHECK-DAG: NoAlias: i8* %gep.inc4, i8* %gep.inc5
;; At limit:
[BasicAA] Remove checks for GEP decomposition limit reached The GEP aliasing code currently checks for the GEP decomposition limit being reached (i.e., we did not reach the "final" underlying object). As far as I can see, these checks are not necessary. It is perfectly fine to work with a GEP whose base can still be further decomposed. Looking back through the commit history, these checks were originally introduced in 1a444489e9d90915cfdda0720489893896ef1503. However, I believe that the problem this was intended to address was later properly fixed with 1726fc698ccb85fe4bb23c200a50f28b57fc53cb, and the checks are no longer necessary since then (and were not the right fix in the first place). Differential Revision: https://reviews.llvm.org/D91010
2020-11-08 02:02:49 +08:00
; CHECK-DAG: MustAlias: i8* %gep.add6, i8* %gep.inc6
; CHECK-DAG: NoAlias: i8* %gep.inc4, i8* %gep.inc6
; CHECK-DAG: NoAlias: i8* %gep.inc5, i8* %gep.inc6
[BasicAA] Add test for decomposition limit (NFC) Test behavior before/at/after the GEP decomposition limit.
2020-11-10 03:42:57 +08:00
;; After limit:
; CHECK-DAG: MayAlias: i8* %gep.add7, i8* %gep.inc7
; CHECK-DAG: MayAlias: i8* %gep.inc5, i8* %gep.inc7
[BasicAA] Remove checks for GEP decomposition limit reached The GEP aliasing code currently checks for the GEP decomposition limit being reached (i.e., we did not reach the "final" underlying object). As far as I can see, these checks are not necessary. It is perfectly fine to work with a GEP whose base can still be further decomposed. Looking back through the commit history, these checks were originally introduced in 1a444489e9d90915cfdda0720489893896ef1503. However, I believe that the problem this was intended to address was later properly fixed with 1726fc698ccb85fe4bb23c200a50f28b57fc53cb, and the checks are no longer necessary since then (and were not the right fix in the first place). Differential Revision: https://reviews.llvm.org/D91010
2020-11-08 02:02:49 +08:00
; CHECK-DAG: NoAlias: i8* %gep.inc6, i8* %gep.inc7
[BasicAA] Add test for decomposition limit (NFC) Test behavior before/at/after the GEP decomposition limit.
2020-11-10 03:42:57 +08:00
define void @test(i8* %base) {
%gep.add5 = getelementptr i8, i8* %base, i64 5
%gep.add6 = getelementptr i8, i8* %base, i64 6
%gep.add7 = getelementptr i8, i8* %base, i64 7
%gep.inc1 = getelementptr i8, i8* %base, i64 1
%gep.inc2 = getelementptr i8, i8* %gep.inc1, i64 1
%gep.inc3 = getelementptr i8, i8* %gep.inc2, i64 1
%gep.inc4 = getelementptr i8, i8* %gep.inc3, i64 1
%gep.inc5 = getelementptr i8, i8* %gep.inc4, i64 1
%gep.inc6 = getelementptr i8, i8* %gep.inc5, i64 1
%gep.inc7 = getelementptr i8, i8* %gep.inc6, i64 1
ret void
}