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Add argmemonly attribute.

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This change adds new attribute called "argmemonly". Function marked with this attribute can only access memory through it's argument pointers. This attribute directly corresponds to the "OnlyAccessesArgumentPointees" ModRef behaviour in alias analysis.

Differential Revision: http://reviews.llvm.org/D10398



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241979 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Igor Laevsky
2015-07-11 10:30:36 +00:00
parent 063b6a0120
commit 6690dbffe0
17 changed files with 167 additions and 35 deletions
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45
test/Analysis/BasicAA/modref.ll
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@@ -145,6 +145,51 @@ entry:
; CHECK: load i32, i32*
}
;; Check that aa correctly handles functions marked with argmemonly
;; attribute.
declare i32 @func_argmemonly(i32 * %P) argmemonly
;; Can not remove redundant load, function may write to it.
; CHECK-LABEL: @test8(
define i32 @test8(i32 *%P) {
%V1 = load i32, i32* %P
call i32 @func_argmemonly(i32* %P)
%V2 = load i32, i32* %P
%Diff = sub i32 %V1, %V2
ret i32 %Diff
; CHECK: load
; CHECK: load
; CHECK: sub
; CHECK: ret i32 %Diff
}
;; In this case load can be removed, function clobbers only %P2.
; CHECK-LABEL: @test9(
define i32 @test9(i32* %P, i32* noalias %P2) {
%V1 = load i32, i32* %P
call i32 @func_argmemonly(i32* %P2)
%V2 = load i32, i32* %P
%Diff = sub i32 %V1, %V2
ret i32 %Diff
; CHECK-NOT: load
; CHECK: ret i32 0
}
;; In this case load can *not* be removed. Function clobers only %P2 but it may
;; alias with %P.
; CHECK-LABEL: @test10(
define i32 @test10(i32* %P, i32* %P2) {
%V1 = load i32, i32* %P
call i32 @func_argmemonly(i32* %P2)
%V2 = load i32, i32* %P
%Diff = sub i32 %V1, %V2
ret i32 %Diff
; CHECK: load
; CHECK: load
; CHECK: sub
; CHECK: ret i32 %Diff
}
declare void @llvm.memset.p0i8.i32(i8* nocapture, i8, i32, i32, i1) nounwind
declare void @llvm.memset.p0i8.i8(i8* nocapture, i8, i8, i32, i1) nounwind
declare void @llvm.memcpy.p0i8.p0i8.i8(i8* nocapture, i8* nocapture, i8, i32, i1) nounwind