Displaying 3 results from an estimated 3 matches for "aliasselect".
2019 Jun 03
2
Question about a AA result and its use in Dependence Analysis
...ment any alias analysis that cares about the precise point in the program; the answer applies to any point in the program dominated by the definitions of both values. This produces useful results because LLVM uses SSA form. Working from that definition, it's easy to see that the logic used in aliasSelect is valid, and that aliasPHI is returning the correct result for the given example. Maybe it's worth calling this out in the alias analysis documentation.
For information across loop iterations, the appropriate analysis is probably LoopAccessAnalysis.
-Eli
> -----Original Message-----
>...
2019 Jun 05
2
Question about a AA result and its use in Dependence Analysis
...ment any alias analysis that cares about the precise point in the program; the answer applies to any point in the program dominated by the definitions of both values. This produces useful results because LLVM uses SSA form. Working from that definition, it's easy to see that the logic used in aliasSelect is valid, and that aliasPHI is returning the correct result for the given example. Maybe it's worth calling this out in the alias analysis documentation.
+1
The flaw here seems to be in the way that DA is using AA. DependenceAnalysis's underlyingObjectsAlias is doing this:
// Check...
2019 Jun 03
2
Question about a AA result and its use in Dependence Analysis
It seems the same bug is there if we do pointer swapping with selects. Do you agree? (see example below)
define void @f() {
entry:
%a1 = alloca float, align 4
%a2 = alloca float, align 4
br label %loop
end:
ret void
loop:
%phi = phi i32 [ 0, %entry ], [ 1, %loop ]
%select_cond = icmp eq i32 %phi, 0
%ptr1 = select i1 %select_cond, float* %a1, float* %a2
%ptr2 = select i1