[AArch64][TableGen] Skip tied result operands for InstAlias

Summary:
This patch fixes an issue so that the right alias is printed when the instruction has tied operands. It checks the number of operands in the resulting instruction as opposed to the alias, and then skips over tied operands that should not be printed in the alias.

This allows to generate the preferred assembly syntax for the AArch64 'ins' instruction, which should always be displayed as 'mov' according to the ARM Architecture Reference Manual. Several unit tests have changed as a result, but only to reflect the preferred disassembly. Some other InstAlias patterns (movk/bic/orr) needed a slight adjustment to stop them becoming the default and breaking other unit tests.

Please note that the patch is mostly the same as https://reviews.llvm.org/D29219 which was reverted because of an issue found when running TableGen with the Address Sanitizer. That issue has been addressed in this iteration of the patch.


Reviewers: rengolin, stoklund, huntergr, SjoerdMeijer, rovka

Reviewed By: rengolin, SjoerdMeijer

Subscribers: fhahn, aemerson, javed.absar, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D40030

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@318650 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 15 insertions, 2 deletions

diff --git a/utils/TableGen/AsmWriterEmitter.cpp b/utils/TableGen/AsmWriterEmitter.cpp
index 52b4c39255f..723c0cd773f 100644
--- a/utils/TableGen/AsmWriterEmitter.cpp
+++ b/utils/TableGen/AsmWriterEmitter.cpp
@@ -820,8 +820,8 @@ void AsmWriterEmitter::EmitPrintAliasInstruction(raw_ostream &O) {
       }
 
       unsigned NumMIOps = 0;
-      for (auto &Operand : CGA.ResultOperands)
-        NumMIOps += Operand.getMINumOperands();
+      for (auto &ResultInstOpnd : CGA.ResultInst->Operands)
+        NumMIOps += ResultInstOpnd.MINumOperands;
 
       std::string Cond;
       Cond = std::string("MI->getNumOperands() == ") + utostr(NumMIOps);
@@ -831,6 +831,19 @@ void AsmWriterEmitter::EmitPrintAliasInstruction(raw_ostream &O) {
 
       unsigned MIOpNum = 0;
       for (unsigned i = 0, e = LastOpNo; i != e; ++i) {
+        // Skip over tied operands as they're not part of an alias declaration.
+        auto &Operands = CGA.ResultInst->Operands;
+        unsigned OpNum = Operands.getSubOperandNumber(MIOpNum).first;
+        if (Operands[OpNum].MINumOperands == 1 &&
+            Operands[OpNum].getTiedRegister() != -1) {
+          // Tied operands of different RegisterClass should be explicit within
+          // an instruction's syntax and so cannot be skipped.
+          int TiedOpNum = Operands[OpNum].getTiedRegister();
+          if (Operands[OpNum].Rec->getName() ==
+              Operands[TiedOpNum].Rec->getName())
+            ++MIOpNum;
+        }
+
         std::string Op = "MI->getOperand(" + utostr(MIOpNum) + ")";
 
         const CodeGenInstAlias::ResultOperand &RO = CGA.ResultOperands[i];