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19046ec19c
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
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