The test is reduced from the example in D82005.
Similar to 94f6d365e, the test here would assert in
the DomTree when we tried to convert a select to a
phi with an unreachable block operand.
We may want to add some kind of guard code in DomTree
itself to avoid this sort of problem.
As it's causing some bot failures (and per request from kbarton).
This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.
llvm-svn: 358546
In PR41304:
https://bugs.llvm.org/show_bug.cgi?id=41304
...we have a case where we want to fold a binop of select-shuffle (blended) values.
Rather than try to match commuted variants of the pattern, we can canonicalize the
shuffles and check for mask equality with commuted operands.
We don't produce arbitrary shuffle masks in instcombine, but select-shuffles are a
special case that the backend is required to handle because we already canonicalize
vector select to this shuffle form.
So there should be no codegen difference from this change. It's possible that this
improves CSE in IR though.
Differential Revision: https://reviews.llvm.org/D60016
llvm-svn: 357366
Summary:
When we fold vector constants that are operands of phi's that feed into select,
we need to set the correct insertion point for the *new* selects that get generated.
The correct insertion point is the incoming block for the phi.
Such cases can occur with patch r298845, which fixed folding of
vector constants, but the new selects could be inserted incorrectly (as the added
test case shows).
Reviewers: majnemer, spatel, sanjoy
Reviewed by: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34162
llvm-svn: 305591
Sanjay Patel