[PATCH] D17221: Don't combine fp_round (fp_round x) if f80 to f16 is generated

[Pirama Arumuga Nainar via llvm-commits]

pirama added inline comments.

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Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:9030
@@ +9029,3 @@
+    // x86.
+    if (N0.getOperand(0).getValueType() == MVT::f80 && VT == MVT::f16)
+      return SDValue();
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ab wrote:
> How do we know that the round is value-preserving?
The first round being value-preserving is a pre-requisite for the folding (the if statement below).  So, this patch doesn't change behavior if the first fp_round is not value-preserving.


http://reviews.llvm.org/D17221