tree 645c94482b2523f977c43607e647feb2036bc90e
parent 8af0cf9929da687fe5f8013ca673f9201fefc8fa
author QingShan Zhang <qshanz@cn.ibm.com> 1561525973 +0000
committer QingShan Zhang <qshanz@cn.ibm.com> 1561525973 +0000

Teach the DAGCombine to fold this pattern(c1 and c2 is constant).

// fold (sext (select cond, c1, c2)) -> (select cond, sext c1, sext c2)
// fold (zext (select cond, c1, c2)) -> (select cond, zext c1, zext c2)
// fold (aext (select cond, c1, c2)) -> (select cond, sext c1, sext c2)
Sign extend the operands if it is any_extend, to keep the signess of the operands that, the other combine rule would apply. The any_extend is handled as zero extend for constants. i.e.

t1: i8 = select t0, Constant:i8<-1>, Constant:i8<0>
t2: i64 = any_extend t1
 -->
t3: i64 = select t0, Constant:i64<-1>, Constant:i64<0>
 -->
t4: i64 = sign_extend_inreg t3

Differential Revision: https://reviews.llvm.org/D63318


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364382 91177308-0d34-0410-b5e6-96231b3b80d8