[PATCH] D60020: [DAGCombiner][X86] Canonicalize SSUBO with immediate RHS to SADDO by negating the immediate.

[Craig Topper via Phabricator via llvm-commits]

craig.topper marked an inline comment as done.
craig.topper added inline comments.


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Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:3049
+    return DAG.getNode(ISD::SADDO, DL, N->getVTList(), N0,
+                       DAG.getConstant(-N1C->getAPIntValue(), DL, VT));
+  }
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RKSimon wrote:
> Might be wrong here, but what happens with (subo x, INT_MIN) ? That can't be expressed as a +ve integer and we're dealing with overflows here....
I think you're right. This generates the opposite value for the overflow flag for INT_MIN.


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  https://reviews.llvm.org/D60020/new/

https://reviews.llvm.org/D60020