[llvm-commits] CVS: llvm/lib/Target/PowerPC/PowerPCInstrInfo.td

[Chris Lattner]

Changes in directory llvm/lib/Target/PowerPC:

PowerPCInstrInfo.td updated: 1.95 -> 1.96
---
Log message:

Introduce two new concepts:
1. Add support for defining Pattern's, which can match expressions when there
   is no instruction that directly implements something.  Instructions usually
   implicitly define patterns.
2. Add support for defining SDNodeXForm's, which are node transformations.
   This seperates the concept of a node xform out from the existing predicate
   support.

Using this new stuff, we add a few instruction patterns, one for testing, and
two for OR/XOR by an arbitrary immediate.



---
Diffs of the changes:  (+75 -11)

 PowerPCInstrInfo.td |   86 +++++++++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 75 insertions(+), 11 deletions(-)


Index: llvm/lib/Target/PowerPC/PowerPCInstrInfo.td
diff -u llvm/lib/Target/PowerPC/PowerPCInstrInfo.td:1.95 llvm/lib/Target/PowerPC/PowerPCInstrInfo.td:1.96
--- llvm/lib/Target/PowerPC/PowerPCInstrInfo.td:1.95	Thu Sep  8 18:17:26 2005
+++ llvm/lib/Target/PowerPC/PowerPCInstrInfo.td	Thu Sep  8 19:39:56 2005
@@ -109,24 +109,44 @@
 def sext_inreg : SDNode<"ISD::SIGN_EXTEND_INREG", SDTExtInreg>;
 def ctlz       : SDNode<"ISD::CTLZ"      , SDTIntUnaryOp>;
 
+//===----------------------------------------------------------------------===//
+// Selection DAG Node Transformation Functions.
+//
+// This mechanism allows targets to manipulate nodes in the output DAG once a
+// match has been formed.  This is typically used to manipulate immediate
+// values.
+//
+class SDNodeXForm<SDNode opc, code xformFunction> {
+  SDNode Opcode = opc;
+  code XFormFunction = xformFunction;
+}
+
+def NOOP_SDNodeXForm : SDNodeXForm<imm, [{}]>;
+
 
 //===----------------------------------------------------------------------===//
 // Selection DAG Pattern Fragments.
 //
+// Pattern fragments are reusable chunks of dags that match specific things.
+// They can take arguments and have C++ predicates that control whether they
+// match.  They are intended to make the patterns for common instructions more
+// compact and readable.
+//
 
 /// PatFrag - Represents a pattern fragment.  This can match something on the
 /// DAG, frame a single node to multiply nested other fragments.
 ///
-class PatFrag<dag ops, dag frag, code pred = [{}], code xform = [{}]> {
+class PatFrag<dag ops, dag frag, code pred = [{}],
+              SDNodeXForm xform = NOOP_SDNodeXForm> {
   dag Operands = ops;
   dag Fragment = frag;
   code Predicate = pred;
-  code OperandTransform = xform;
+  SDNodeXForm OperandTransform = xform;
 }
 
 // PatLeaf's are pattern fragments that have no operands.  This is just a helper
 // to define immediates and other common things concisely.
-class PatLeaf<dag frag, code pred = [{}], code xform = [{}]>
+class PatLeaf<dag frag, code pred = [{}], SDNodeXForm xform = NOOP_SDNodeXForm>
  : PatFrag<(ops), frag, pred, xform>;
 
 // Leaf fragments.
@@ -142,10 +162,39 @@
 def not  : PatFrag<(ops node:$in), (xor node:$in, immAllOnes)>;
 def ineg : PatFrag<(ops node:$in), (sub immZero, node:$in)>;
 
+//===----------------------------------------------------------------------===//
+// Selection DAG Pattern Support.
+//
+// Patterns are what are actually matched against the target-flavored
+// instruction selection DAG.  Instructions defined by the target implicitly
+// define patterns in most cases, but patterns can also be explicitly added when
+// an operation is defined by a sequence of instructions (e.g. loading a large
+// immediate value on RISC targets that do not support immediates as large as
+// their GPRs).
+//
+
+class Pattern<dag patternToMatch, list<dag> resultInstrs> {
+  dag       PatternToMatch = patternToMatch;
+  list<dag> ResultInstrs   = resultInstrs;
+}
+
+// Pat - A simple (but common) form of a pattern, which produces a simple result
+// not needing a full list.
+class Pat<dag pattern, dag result> : Pattern<pattern, [result]>;
 
 
 //===----------------------------------------------------------------------===//
-// PowerPC specific pattern fragments.
+// PowerPC specific transformation functions and pattern fragments.
+//
+def LO16 : SDNodeXForm<imm, [{
+  // Transformation function: get the low 16 bits.
+  return getI32Imm((unsigned short)N->getValue());
+}]>;
+
+def HI16 : SDNodeXForm<imm, [{
+  // Transformation function: shift the immediate value down into the low bits.
+  return getI32Imm((unsigned)N->getValue() >> 16);
+}]>;
 
 def immSExt16  : PatLeaf<(imm), [{
   // immSExt16 predicate - True if the immediate fits in a 16-bit sign extended
@@ -156,15 +205,13 @@
   // immZExt16 predicate - True if the immediate fits in a 16-bit zero extended
   // field.  Used by instructions like 'ori'.
   return (unsigned)N->getValue() == (unsigned short)N->getValue();
-}]>;
+}], LO16>;
+
 def imm16Shifted : PatLeaf<(imm), [{
   // imm16Shifted predicate - True if only bits in the top 16-bits of the
   // immediate are set.  Used by instructions like 'addis'.
   return ((unsigned)N->getValue() & 0xFFFF0000U) == (unsigned)N->getValue();
-}], [{
-  // Transformation function: shift the immediate value down into the low bits.
-  return getI32Imm((unsigned)N->getValue() >> 16);
-}]>;
+}], HI16>;
 
 /*
 // Example of a legalize expander: Only for PPC64.
@@ -176,8 +223,6 @@
                 Subtarget_PPC64>;
 */
 
-
-
 //===----------------------------------------------------------------------===//
 // PowerPC Flag Definitions.
 
@@ -712,6 +757,24 @@
                       (ops GPRC:$rA, GPRC:$rS, u6imm:$SH, u6imm:$ME),
                       "rldicr $rA, $rS, $SH, $ME">, isPPC64;
 
+//===----------------------------------------------------------------------===//
+// PowerPC Instruction Patterns
+//
+
+// REDUNDANT WITH INSTRUCTION DEFINITION, ONLY FOR TESTING.
+def : Pat<(sext_inreg GPRC:$in, i8),
+          (EXTSB GPRC:$in)>;
+          
+// or by an arbitrary immediate.
+def : Pat<(or GPRC:$in, imm:$imm),
+          (ORIS (ORI GPRC:$in, (LO16 imm:$imm)), (HI16 imm:$imm))>;
+// xor by an arbitrary immediate.
+def : Pat<(xor GPRC:$in, imm:$imm),
+          (XORIS (XORI GPRC:$in, (LO16 imm:$imm)), (HI16 imm:$imm))>;
+
+//===----------------------------------------------------------------------===//
+// PowerPCInstrInfo Definition
+//
 def PowerPCInstrInfo : InstrInfo {
   let PHIInst  = PHI;
 
@@ -720,3 +783,4 @@
 
   let isLittleEndianEncoding = 1;
 }
+