[PATCH] D48467: [X86] Recognize an fnma in the presence of an intervening shuffle.

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


================
Comment at: lib/Target/X86/X86ISelLowering.cpp:31185
+    return Negate(Op0, Op1);
+}
+
----------------
Please move the isFNEG as a NFC commit


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Comment at: lib/Target/X86/X86ISelLowering.cpp:31210
+      break;
+    }
+  if (!UsedByFMA)
----------------
Can this be written as a llvm::any_of pattern?


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Comment at: lib/Target/X86/X86ISelLowering.cpp:31214
+
+  ShuffleVectorSDNode *SVOp = dyn_cast<ShuffleVectorSDNode>(N);
+  auto NegOp0 = isFNEG(N->getOperand(0).getNode());
----------------
Early out if !SVOp || !SVOp->isSplat()


================
Comment at: lib/Target/X86/X86ISelLowering.cpp:31215
+  ShuffleVectorSDNode *SVOp = dyn_cast<ShuffleVectorSDNode>(N);
+  auto NegOp0 = isFNEG(N->getOperand(0).getNode());
+
----------------
Don't use auto for non-obvious (casts etc.) cases.


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Comment at: lib/Target/X86/X86ISelLowering.cpp:31218
+  if (SVOp && SVOp->isSplat() && NegOp0.getNode() &&
+      N->getOperand(1).isUndef()) {
+    EVT VT = N->getValueType(0);
----------------
Its unlikely that Op1 isn't undef, but if you have cases of this you could handle both ops but testing SVOp->getSplatIndex()


Repository:
  rL LLVM

https://reviews.llvm.org/D48467