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llvm-project/llvm/test/Analysis/BasicAA/phi-aa.ll
Nikita Popov f197cf2126 [BasicAA] Merge aliasGEP code paths 
At this point, we can treat the case of GEP/GEP aliasing and
GEP/non-GEP aliasing in essentially the same way. The only
differences are that we need to do an additional negative GEP base
check, and that we perform a bailout on unknown sizes for the
GEP/non-GEP case (the latter exists only to limit compile-time).

This change is not quite NFC due to the peculiar effect that
the DecomposedGEP for V2 can actually be non-trivial even if V2
is not a GEP. The reason for this is that getUnderlyingObject()
can look through LCSSA phi nodes, while stripPointerCasts() doesn't.
This can lead to slightly better results if single-entry phi nodes
occur inside a loop, where looking through the phi node via aliasPhi()
would subject it to phi cycle equivalence restrictions. It would
probably make sense to adjust pointer cast stripping (for AA) to
handle this case, and ensure consistent results.
2021-02-14 19:35:36 +01:00

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; RUN: opt < %s -phi-values -basic-aa -aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
; RUN: opt < %s -aa-pipeline=basic-aa -passes='require<phi-values>,aa-eval' -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
; rdar://7282591
@X = common global i32 0
@Y = common global i32 0
@Z = common global i32 0
; CHECK-LABEL: foo
; CHECK: NoAlias: i32* %P, i32* @Z
define void @foo(i32 %cond) nounwind {
entry:
%"alloca point" = bitcast i32 0 to i32
%tmp = icmp ne i32 %cond, 0
br i1 %tmp, label %bb, label %bb1
bb:
br label %bb2
bb1:
br label %bb2
bb2:
%P = phi i32* [ @X, %bb ], [ @Y, %bb1 ]
%tmp1 = load i32, i32* @Z, align 4
store i32 123, i32* %P, align 4
%tmp2 = load i32, i32* @Z, align 4
br label %return
return:
ret void
}
; Pointers can vary in between iterations of loops.
; PR18068
; CHECK-LABEL: pr18068
; CHECK: MayAlias: i32* %0, i32* %arrayidx5
; CHECK: NoAlias: i32* %arrayidx13, i32* %arrayidx5
define i32 @pr18068(i32* %jj7, i32* %j) {
entry:
%oa5 = alloca [100 x i32], align 16
br label %codeRepl
codeRepl:
%0 = phi i32* [ %arrayidx13, %for.body ], [ %j, %entry ]
%targetBlock = call i1 @cond(i32* %jj7)
br i1 %targetBlock, label %for.body, label %bye
for.body:
%1 = load i32, i32* %jj7, align 4
%idxprom4 = zext i32 %1 to i64
%arrayidx5 = getelementptr inbounds [100 x i32], [100 x i32]* %oa5, i64 0, i64 %idxprom4
%2 = load i32, i32* %arrayidx5, align 4
%sub6 = sub i32 %2, 6
store i32 %sub6, i32* %arrayidx5, align 4
; %0 and %arrayidx5 can alias! It is not safe to DSE the above store.
%3 = load i32, i32* %0, align 4
store i32 %3, i32* %arrayidx5, align 4
%sub11 = add i32 %1, -1
%idxprom12 = zext i32 %sub11 to i64
%arrayidx13 = getelementptr inbounds [100 x i32], [100 x i32]* %oa5, i64 0, i64 %idxprom12
call void @inc(i32* %jj7)
br label %codeRepl
bye:
%.reload = load i32, i32* %jj7, align 4
ret i32 %.reload
}
declare i1 @cond(i32*)
declare void @inc(i32*)
; When we have a chain of phis in nested loops we should recognise if there's
; actually only one underlying value.
; CHECK-LABEL: loop_phi_chain
; CHECK: NoAlias: i32* %val1, i32* @Y
; CHECK: NoAlias: i32* %val2, i32* @Y
; CHECK: NoAlias: i32* %val3, i32* @Y
define void @loop_phi_chain(i32 %a, i32 %b, i32 %c) {
entry:
br label %loop1
loop1:
%n1 = phi i32 [ 0, %entry ], [ %add1, %loop2 ]
%val1 = phi i32* [ @X, %entry ], [ %val2, %loop2 ]
%add1 = add i32 %n1, 1
%cmp1 = icmp ne i32 %n1, 32
br i1 %cmp1, label %loop2, label %end
loop2:
%n2 = phi i32 [ 0, %loop1 ], [ %add2, %loop3 ]
%val2 = phi i32* [ %val1, %loop1 ], [ %val3, %loop3 ]
%add2 = add i32 %n2, 1
%cmp2 = icmp ne i32 %n2, 32
br i1 %cmp2, label %loop3, label %loop1
loop3:
%n3 = phi i32 [ 0, %loop2 ], [ %add3, %loop3 ]
%val3 = phi i32* [ %val2, %loop2 ], [ %val3, %loop3 ]
store i32 0, i32* %val3, align 4
store i32 0, i32* @Y, align 4
%add3 = add i32 %n3, 1
%cmp3 = icmp ne i32 %n3, 32
br i1 %cmp3, label %loop3, label %loop2
end:
ret void
}
; CHECK-LABEL: phi_and_select
; CHECK: MustAlias: i32* %p, i32* %s
define void @phi_and_select(i1 %c, i1 %c2, i32* %x, i32* %y) {
entry:
br i1 %c, label %true, label %false
true:
br label %exit
false:
br label %exit
exit:
%p = phi i32* [ %x, %true ], [ %y, %false ]
%s = select i1 %c2, i32* %p, i32* %p
store i32 0, i32* %p
store i32 0, i32* %s
ret void
}
; CHECK-LABEL: phi_and_phi_cycle
; CHECK: NoAlias: i32* %p1, i32* %p2
define void @phi_and_phi_cycle(i32* noalias %x, i32* noalias %y) {
entry:
br label %loop
loop:
%p1 = phi i32* [ %x, %entry ], [ %p1.next, %loop ]
%p2 = phi i32* [ %y, %entry ], [ %p2.next, %loop ]
%p1.next = getelementptr i32, i32* %p1, i64 1
%p2.next = getelementptr i32, i32* %p1, i64 2
store i32 0, i32* %p1
store i32 0, i32* %p2
br label %loop
}
; CHECK-LABEL: phi_and_gep_unknown_size
; CHECK: Just Mod: call void @llvm.memset.p0i8.i32(i8* %g, i8 0, i32 %size, i1 false) <-> call void @llvm.memset.p0i8.i32(i8* %z, i8 0, i32 %size, i1 false)
; TODO: This should be NoModRef.
define void @phi_and_gep_unknown_size(i1 %c, i8* %x, i8* %y, i8* noalias %z, i32 %size) {
entry:
br i1 %c, label %true, label %false
true:
br label %exit
false:
br label %exit
exit:
%p = phi i8* [ %x, %true ], [ %y, %false ]
%g = getelementptr inbounds i8, i8* %p, i64 1
call void @llvm.memset.p0i8.i32(i8* %g, i8 0, i32 %size, i1 false)
call void @llvm.memset.p0i8.i32(i8* %z, i8 0, i32 %size, i1 false)
ret void
}
declare void @llvm.memset.p0i8.i32(i8*, i8, i32, i1)
; CHECK-LABEL: unsound_inequality
; CHECK: MayAlias: i32* %arrayidx13, i32* %phi
; CHECK: MayAlias: i32* %arrayidx5, i32* %phi
; CHECK: NoAlias: i32* %arrayidx13, i32* %arrayidx5
; When recursively reasoning about phis, we can't use predicates between
; two values as we might be comparing the two from different iterations.
define i32 @unsound_inequality(i32* %jj7, i32* %j) {
entry:
%oa5 = alloca [100 x i32], align 16
br label %for.body
for.body: ; preds = %for.body, %entry
%phi = phi i32* [ %arrayidx13, %for.body ], [ %j, %entry ]
%idx = load i32, i32* %jj7, align 4
%arrayidx5 = getelementptr inbounds [100 x i32], [100 x i32]* %oa5, i64 0, i32 %idx
store i32 0, i32* %arrayidx5, align 4
store i32 0, i32* %phi, align 4
%notequal = add i32 %idx, 1
%arrayidx13 = getelementptr inbounds [100 x i32], [100 x i32]* %oa5, i64 0, i32 %notequal
store i32 0, i32* %arrayidx13, align 4
br label %for.body
}
; CHECK-LABEL: single_arg_phi
; CHECK: MayAlias: i32* %ptr, i32* %ptr.next
; CHECK: MustAlias: i32* %ptr.next, i32* %ptr.next.phi
; TODO: The first one could be MustAlias as well.
define void @single_arg_phi(i32* %ptr.base) {
entry:
br label %loop
loop:
%ptr = phi i32* [ %ptr.base, %entry ], [ %ptr.next, %split ]
%ptr.next = getelementptr inbounds i32, i32* %ptr, i64 1
br label %split
split:
%ptr.phi = phi i32* [ %ptr, %loop ]
%ptr.next.phi = phi i32* [ %ptr.next, %loop ]
br label %loop
}
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