Extend TableGen instruction selection matcher to improve handling

of complex instruction operands (e.g. address modes).

Currently, if a Pat pattern creates an instruction that has a complex
operand (i.e. one that consists of multiple sub-operands at the MI
level), this operand must match a ComplexPattern DAG pattern with the
correct number of output operands.

This commit extends TableGen to alternatively allow match a complex
operands against multiple separate operands at the DAG level.

This allows using Pat patterns to match pre-increment nodes like
pre_store (which must have separate operands at the DAG level) onto
an instruction pattern that uses a multi-operand memory operand,
like the following example on PowerPC (will be committed as a
follow-on patch):

  def STWU  : DForm_1<37, (outs ptr_rc:$ea_res), (ins GPRC:$rS, memri:$dst),
                    "stwu $rS, $dst", LdStStoreUpd, []>,
                    RegConstraint<"$dst.reg = $ea_res">, NoEncode<"$ea_res">;

  def : Pat<(pre_store GPRC:$rS, ptr_rc:$ptrreg, iaddroff:$ptroff),
            (STWU GPRC:$rS, iaddroff:$ptroff, ptr_rc:$ptrreg)>;

Here, the pair of "ptroff" and "ptrreg" operands is matched onto the
complex operand "dst" of class "memri" in the "STWU" instruction.

Approved by Jakob Stoklund Olesen.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177428 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 23 insertions, 10 deletions

diff --git a/utils/TableGen/DAGISelMatcherGen.cpp b/utils/TableGen/DAGISelMatcherGen.cpp
index 38ffa30ec8..8541390b41 100644
--- a/utils/TableGen/DAGISelMatcherGen.cpp
+++ b/utils/TableGen/DAGISelMatcherGen.cpp
@@ -734,20 +734,33 @@ EmitResultInstructionAsOperand(const TreePatternNode *N,
       continue;
     }
 
-    const TreePatternNode *Child = N->getChild(ChildNo);
-
     // Otherwise this is a normal operand or a predicate operand without
     // 'execute always'; emit it.
-    unsigned BeforeAddingNumOps = InstOps.size();
-    EmitResultOperand(Child, InstOps);
-    assert(InstOps.size() > BeforeAddingNumOps && "Didn't add any operands");
 
-    // If the operand is an instruction and it produced multiple results, just
-    // take the first one.
-    if (!Child->isLeaf() && Child->getOperator()->isSubClassOf("Instruction"))
-      InstOps.resize(BeforeAddingNumOps+1);
+    // For operands with multiple sub-operands we may need to emit
+    // multiple child patterns to cover them all.  However, ComplexPattern
+    // children may themselves emit multiple MI operands.
+    unsigned NumSubOps = 1;
+    if (OperandNode->isSubClassOf("Operand")) {
+      DagInit *MIOpInfo = OperandNode->getValueAsDag("MIOperandInfo");
+      if (unsigned NumArgs = MIOpInfo->getNumArgs())
+        NumSubOps = NumArgs;
+    }
+
+    unsigned FinalNumOps = InstOps.size() + NumSubOps;
+    while (InstOps.size() < FinalNumOps) {
+      const TreePatternNode *Child = N->getChild(ChildNo);
+      unsigned BeforeAddingNumOps = InstOps.size();
+      EmitResultOperand(Child, InstOps);
+      assert(InstOps.size() > BeforeAddingNumOps && "Didn't add any operands");
 
-    ++ChildNo;
+      // If the operand is an instruction and it produced multiple results, just
+      // take the first one.
+      if (!Child->isLeaf() && Child->getOperator()->isSubClassOf("Instruction"))
+        InstOps.resize(BeforeAddingNumOps+1);
+
+      ++ChildNo;
+    }
   }
 
   // If this node has input glue or explicitly specified input physregs, we