add TableGen support to create relationship maps between instructions

Relationship maps are represented as InstrMapping records which are parsed by
TableGen and the information is used to construct mapping tables to represent
appropriate relations between instructions. These tables are emitted into
XXXGenInstrInfo.inc file along with the functions to query them.

Patch by Jyotsna Verma <jverma@codeaurora.org>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166685 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 49 insertions, 0 deletions

diff --git a/include/llvm/Target/Target.td b/include/llvm/Target/Target.td
index a68eb8339d..12f5c0eb30 100644
--- a/include/llvm/Target/Target.td
+++ b/include/llvm/Target/Target.td
@@ -998,6 +998,55 @@ class ProcessorModel<string n, SchedMachineModel m, list<SubtargetFeature> f>
 }
 
 //===----------------------------------------------------------------------===//
+// InstrMapping - This class is used to create mapping tables to relate
+// instructions with each other based on the values specified in RowFields,
+// ColFields, KeyCol and ValueCols.
+//
+class InstrMapping {
+  // FilterClass - Used to limit search space only to the instructions that
+  // define the relationship modeled by this InstrMapping record.
+  string FilterClass;
+
+  // RowFields - List of fields/attributes that should be same for all the
+  // instructions in a row of the relation table. Think of this as a set of
+  // properties shared by all the instructions related by this relationship
+  // model and is used to categorize instructions into subgroups. For instance,
+  // if we want to define a relation that maps 'Add' instruction to its
+  // predicated forms, we can define RowFields like this:
+  //
+  // let RowFields = BaseOp
+  // All add instruction predicated/non-predicated will have to set their BaseOp
+  // to the same value.
+  //
+  // def Add: { let BaseOp = 'ADD'; let predSense = 'nopred' }
+  // def Add_predtrue: { let BaseOp = 'ADD'; let predSense = 'true' }
+  // def Add_predfalse: { let BaseOp = 'ADD'; let predSense = 'false'  }
+  list<string> RowFields = [];
+
+  // List of fields/attributes that are same for all the instructions
+  // in a column of the relation table.
+  // Ex: let ColFields = 'predSense' -- It means that the columns are arranged
+  // based on the 'predSense' values. All the instruction in a specific
+  // column have the same value and it is fixed for the column according
+  // to the values set in 'ValueCols'.
+  list<string> ColFields = [];
+
+  // Values for the fields/attributes listed in 'ColFields'.
+  // Ex: let KeyCol = 'nopred' -- It means that the key instruction (instruction
+  // that models this relation) should be non-predicated.
+  // In the example above, 'Add' is the key instruction.
+  list<string> KeyCol = [];
+
+  // List of values for the fields/attributes listed in 'ColFields', one for
+  // each column in the relation table.
+  //
+  // Ex: let ValueCols = [['true'],['false']] -- It adds two columns in the
+  // table. First column requires all the instructions to have predSense
+  // set to 'true' and second column requires it to be 'false'.
+  list<list<string> > ValueCols = [];
+}
+
+//===----------------------------------------------------------------------===//
 // Pull in the common support for calling conventions.
 //
 include "llvm/Target/TargetCallingConv.td"