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BasicAA: Recognize inttoptr as isEscapeSource

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Pointers escape when converted to integers, so a pointer produced by
converting an integer to a pointer must not be a local non-escaping
object.

Reviewed By: nikic, nlopes, aqjune

Differential Revision: https://reviews.llvm.org/D101541
This commit is contained in:
Joseph Tremoulet 2021-05-07 07:48:18 -07:00
parent 0a6f11aabd
commit bc302bfbef
2 changed files with 68 additions and 0 deletions
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8
llvm/lib/Analysis/BasicAliasAnalysis.cpp
View File

@ -129,6 +129,14 @@ static bool isEscapeSource(const Value *V) {
if (isa<LoadInst>(V))
return true;
// The inttoptr case works because isNonEscapingLocalObject considers all
// means of converting or equating a pointer to an int (ptrtoint, ptr store
// which could be followed by an integer load, ptr<->int compare) as
// escaping, and objects located at well-known addresses via platform-specific
// means cannot be considered non-escaping local objects.
if (isa<IntToPtrInst>(V))
return true;
return false;
}

60
llvm/test/Analysis/BasicAA/noalias-inttoptr.ll Normal file
View File

@ -0,0 +1,60 @@
; RUN: opt < %s -basic-aa -aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
target datalayout = "p:64:64"
declare void @escape(i8* %ptr)
; Verify that unescaped noalias parameter does not alias inttoptr
define void @test1(i8* noalias %P, i64 %Q_as_int) {
; CHECK-LABEL: Function: test1:
; CHECK: NoAlias: i8* %P, i8* %Q
%Q = inttoptr i64 %Q_as_int to i8*
store i8 0, i8* %P
store i8 1, i8* %Q
ret void
}
; Verify that unescaped alloca does not alias inttoptr
define void @test2(i64 %Q_as_int) {
; CHECK-LABEL: Function: test2:
; CHECK: NoAlias: i8* %P, i8* %Q
%P = alloca i8
%Q = inttoptr i64 %Q_as_int to i8*
store i8 0, i8* %P
store i8 1, i8* %Q
ret void
}
; Verify that escaped noalias parameter may alias inttoptr
define void @test3(i8* noalias %P, i64 %Q_as_int) {
; CHECK-LABEL: Function: test3:
; CHECK: MayAlias: i8* %P, i8* %Q
call void @escape(i8* %P)
%Q = inttoptr i64 %Q_as_int to i8*
store i8 0, i8* %P
store i8 1, i8* %Q
ret void
}
; Verify that escaped alloca may alias inttoptr
define void @test4(i64 %Q_as_int) {
; CHECK-LABEL: Function: test4:
; CHECK: MayAlias: i8* %P, i8* %Q
%P = alloca i8
call void @escape(i8* %P)
%Q = inttoptr i64 %Q_as_int to i8*
store i8 0, i8* %P
store i8 1, i8* %Q
ret void
}
; Verify that global may alias inttoptr
@G = external global i8
define void @test5(i64 %Q_as_int) {
; CHECK-LABEL: Function: test5:
; CHECK: MayAlias: i8* %Q, i8* @G
%Q = inttoptr i64 %Q_as_int to i8*
store i8 0, i8* @G
store i8 1, i8* %Q
ret void
}