[PATCH] D74803: TableGen: Fix logic for default operands

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: simon_tatham, SjoerdMeijer, dsanders, paquette.
Herald added a subscriber: wdng.
Herald added a project: LLVM.
arsenm added a child revision: D74804: AMDGPU: Use undef_tied_input on VOP3P instructions.

This was checking for default operands in the current DAG instruction,
rather than the correct result operand list. I'm not entirely sure how
this managed to work before, but was failing for me when multiple
default operands were overridden.


https://reviews.llvm.org/D74803

Files:
  llvm/utils/TableGen/CodeGenDAGPatterns.cpp


Index: llvm/utils/TableGen/CodeGenDAGPatterns.cpp
===================================================================
--- llvm/utils/TableGen/CodeGenDAGPatterns.cpp
+++ llvm/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -2520,6 +2520,9 @@
       }
     }
 
+    unsigned NumResults = Inst.getNumResults();
+    unsigned NumFixedOperands = InstInfo.Operands.size();
+
     // If one or more operands with a default value appear at the end of the
     // formal operand list for an instruction, we allow them to be overridden
     // by optional operands provided in the pattern.
@@ -2528,14 +2531,15 @@
     // operand A with a default, then we don't allow A to be overridden,
     // because there would be no way to specify whether the next operand in
     // the pattern was intended to override A or skip it.
-    unsigned NonOverridableOperands = Inst.getNumOperands();
-    while (NonOverridableOperands > 0 &&
-           CDP.operandHasDefault(Inst.getOperand(NonOverridableOperands-1)))
+    unsigned NonOverridableOperands = NumFixedOperands;
+    while (NonOverridableOperands > NumResults &&
+           CDP.operandHasDefault(InstInfo.Operands[NonOverridableOperands-1].Rec))
       --NonOverridableOperands;
 
     unsigned ChildNo = 0;
-    for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i) {
-      Record *OperandNode = Inst.getOperand(i);
+    assert(NumResults <= NumFixedOperands);
+    for (unsigned i = NumResults, e = NumFixedOperands; i != e; ++i) {
+      Record *OperandNode = InstInfo.Operands[i].Rec;
 
       // If the operand has a default value, do we use it? We must use the
       // default if we've run out of children of the pattern DAG to consume,


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