[PATCH] D41811: X86: Add pattern matching for PMADDWD

[Zvi Rackover via Phabricator via llvm-commits]

zvi added inline comments.


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Comment at: lib/Target/X86/X86ISelLowering.cpp:37062
+      SDValue Op, ArrayRef<unsigned> ExpectedIndices, SDValue &RetMul) {
+    if (Op->getOpcode() != ISD::BUILD_VECTOR)
+      return false;
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craig.topper wrote:
> What ensures the multiply has exactly 2X the elements of the build_vector? Couldn't it have more? Which would cause the truncate later to fail.
You're right! Will fix and add tests


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Comment at: lib/Target/X86/X86ISelLowering.cpp:37087
+  SDValue L, R;
+  const unsigned ExpectedEvenIndices[] = {0,  2,  4,  6,  8,  10, 12, 14,
+                                          16, 18, 20, 22, 24, 26, 28, 30};
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craig.topper wrote:
> Is there anything that guarantees even indices will be on the LHS?
Will add checks for both orderings. thanks


https://reviews.llvm.org/D41811