From 5b52f6d655e34de5c6fedbb71b6c94775cc10032 Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Tue, 24 Jan 2012 18:06:05 +0000
Subject: Add an (interleave A, B, ...) SetTheory operator.

This will interleave the elements from two or more lists.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148824 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Target/Target.td |  3 +++
 test/TableGen/SetTheory.td    |  7 +++++++
 utils/TableGen/SetTheory.cpp  | 19 +++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/include/llvm/Target/Target.td b/include/llvm/Target/Target.td
index f9f30a8bb7..84e6b1bfef 100644
--- a/include/llvm/Target/Target.td
+++ b/include/llvm/Target/Target.td
@@ -200,12 +200,15 @@ class RegisterClass<string namespace, list<ValueType> regTypes, int alignment,
 //
 // (decimate GPR, 2) - Pick every N'th element, starting with the first.
 //
+// (interleave A, B, ...) - Interleave the elements from each argument list.
+//
 // All of these operators work on ordered sets, not lists. That means
 // duplicates are removed from sub-expressions.
 
 // Set operators. The rest is defined in TargetSelectionDAG.td.
 def sequence;
 def decimate;
+def interleave;
 
 // RegisterTuples - Automatically generate super-registers by forming tuples of
 // sub-registers. This is useful for modeling register sequence constraints
diff --git a/test/TableGen/SetTheory.td b/test/TableGen/SetTheory.td
index a4acea907d..4d85aa3e6f 100644
--- a/test/TableGen/SetTheory.td
+++ b/test/TableGen/SetTheory.td
@@ -165,3 +165,10 @@ def S9d : Set<(sequence "S%ua", 7, 9)>;
 // CHECK: S9b = [ e7 e6 e5 e4 e3 ]
 // CHECK: S9c = [ e0 ]
 // CHECK: S9d = [ a b c d e0 e3 e6 e9 e4 e5 e7 ]
+
+// The 'interleave' operator is almost the inverse of 'decimate'.
+def interleave;
+def T0a : Set<(interleave S9a, S9b)>;
+def T0b : Set<(interleave S8e, S8d)>;
+// CHECK: T0a = [ e3 e7 e4 e6 e5 ]
+// CHECK: T0b = [ e0 e1 e2 e3 e4 e5 e6 e7 e8 e9 ]
diff --git a/utils/TableGen/SetTheory.cpp b/utils/TableGen/SetTheory.cpp
index 838b9246aa..0649fd1cfa 100644
--- a/utils/TableGen/SetTheory.cpp
+++ b/utils/TableGen/SetTheory.cpp
@@ -139,6 +139,24 @@ struct DecimateOp : public SetIntBinOp {
   }
 };
 
+// (interleave S1, S2, ...) Interleave elements of the arguments.
+struct InterleaveOp : public SetTheory::Operator {
+  void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
+    // Evaluate the arguments individually.
+    SmallVector<RecSet, 4> Args(Expr->getNumArgs());
+    unsigned MaxSize = 0;
+    for (unsigned i = 0, e = Expr->getNumArgs(); i != e; ++i) {
+      ST.evaluate(Expr->getArg(i), Args[i]);
+      MaxSize = std::max(MaxSize, unsigned(Args[i].size()));
+    }
+    // Interleave arguments into Elts.
+    for (unsigned n = 0; n != MaxSize; ++n)
+      for (unsigned i = 0, e = Expr->getNumArgs(); i != e; ++i)
+        if (n < Args[i].size())
+          Elts.insert(Args[i][n]);
+  }
+};
+
 // (sequence "Format", From, To) Generate a sequence of records by name.
 struct SequenceOp : public SetTheory::Operator {
   void apply(SetTheory &ST, DagInit *Expr, RecSet &Elts) {
@@ -211,6 +229,7 @@ SetTheory::SetTheory() {
   addOperator("rotl", new RotOp(false));
   addOperator("rotr", new RotOp(true));
   addOperator("decimate", new DecimateOp);
+  addOperator("interleave", new InterleaveOp);
   addOperator("sequence", new SequenceOp);
 }
 
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