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

Description

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

Details

Committed
qshanzJun 25 2019, 10:12 PM
Differential Revision
D63318: [DAGCombine] Teach DAGCombine to fold the aext + select pattern
Parents
rL364381: [HIP] Support attribute hip_pinned_shadow
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