Fix SCEVExpander creating distinct duplicate PHI entries
This fixes SCEVExpander so that it does not create multiple distinct induction
variables for duplicate PHI entries. Specifically, given some code like this:
do.body6: ; preds = %do.body6, %do.body6, %if.then5
%end.0 = phi i8* [ undef, %if.then5 ], [ %incdec.ptr, %do.body6 ], [ %incdec.ptr, %do.body6 ]
...
Note that it is legal to have multiple entries for a basic block so long as the
associated value is the same. So the above input is okay, but expanding an
AddRec in this loop could produce code like this:
do.body6: ; preds = %do.body6, %do.body6, %if.then5
%indvar = phi i64 [ %indvar.next, %do.body6 ], [ %indvar.next1, %do.body6 ], [ 0, %if.then5 ]
%end.0 = phi i8* [ undef, %if.then5 ], [ %incdec.ptr, %do.body6 ], [ %incdec.ptr, %do.body6 ]
...
%indvar.next = add i64 %indvar, 1
%indvar.next1 = add i64 %indvar, 1
And this is not legal because there are two PHI entries for %do.body6 each with
a distinct value.
Unfortunately, I don't have an in-tree test case.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188614 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed