[PATCH] D56156: [DAGCombiner][X86][PowerPC] Teach visitSIGN_EXTEND_INREG to fold (sext_in_reg (aext/sext x)) -> (sext x) when x has more than 1 sign bit and the sext_inreg is from one of them.

Sun Dec 30 07:32:35 PST 2018

hfinkel added inline comments.

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Comment at: test/CodeGen/PowerPC/f128-truncateNconv.ll:358
 ; CHECK-NEXT:    mfvsrwz r3, v2
-; CHECK-NEXT:    extsh r3, r3
+; CHECK-NEXT:    extsw r3, r3
 ; CHECK-NEXT:    blr
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This test-case change looks technically correct (note that this will change behavior of programs with UB (if the value being converted to an integer wasn't really representable in the smaller integer size)).

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D56156/new/

https://reviews.llvm.org/D56156