[PATCH] D35998: [TableGen] AsmMatcher: fix OpIdx computation when HasOptionalOperands is true

[Alexandru Guduleasa via Phabricator via llvm-commits]

alexandru.guduleasa updated this revision to Diff 108707.
alexandru.guduleasa added a comment.

Added requested comment.


https://reviews.llvm.org/D35998

Files:
  utils/TableGen/AsmMatcherEmitter.cpp


Index: utils/TableGen/AsmMatcherEmitter.cpp
===================================================================
--- utils/TableGen/AsmMatcherEmitter.cpp
+++ utils/TableGen/AsmMatcherEmitter.cpp
@@ -1847,13 +1847,31 @@
   CvtOS << "  assert(Kind < CVT_NUM_SIGNATURES && \"Invalid signature!\");\n";
   CvtOS << "  const uint8_t *Converter = ConversionTable[Kind];\n";
   if (HasOptionalOperands) {
-    CvtOS << "  unsigned NumDefaults = 0;\n";
+    // If we have optional operands, these may not be present in the Operands
+    // vector.
+    // When we access a certain operand in this vector, we need to compensate
+    // for any missing operand (which will receive the default value).
+    // Since the operand order in the asm-string may not be the same as the
+    // operand order from the MCInst, we compute the array with the number
+    // of default operands before our current index.
+    size_t MaxNumOperands = 0;
+    for (const auto &MI : Infos) {
+      MaxNumOperands = std::max(MaxNumOperands, MI->AsmOperands.size());
+    }
+    CvtOS << "  unsigned DefaultsOffset[" << (MaxNumOperands) << "];\n";
+    CvtOS << "  assert(OptionalOperandsMask.size() == " << (MaxNumOperands)
+          << ");\n";
+    CvtOS << "  for (unsigned i = 0, NumDefaults = 0; i < " << (MaxNumOperands)
+          << "; ++i) {\n";
+    CvtOS << "    DefaultsOffset[i] = NumDefaults;\n";
+    CvtOS << "    NumDefaults += (OptionalOperandsMask[i] ? 1 : 0);\n";
+    CvtOS << "  }\n";
   }
   CvtOS << "  unsigned OpIdx;\n";
   CvtOS << "  Inst.setOpcode(Opcode);\n";
   CvtOS << "  for (const uint8_t *p = Converter; *p; p+= 2) {\n";
   if (HasOptionalOperands) {
-    CvtOS << "    OpIdx = *(p + 1) - NumDefaults;\n";
+    CvtOS << "    OpIdx = *(p + 1) - DefaultsOffset[*(p + 1) - 1];\n";
   } else {
     CvtOS << "    OpIdx = *(p + 1);\n";
   }
@@ -1988,7 +1999,6 @@
                 << "        " << Op.Class->DefaultMethod << "()"
                 << "->" << Op.Class->RenderMethod << "(Inst, "
                 << OpInfo.MINumOperands << ");\n"
-                << "        ++NumDefaults;\n"
                 << "      } else {\n"
                 << "        static_cast<" << TargetOperandClass
                 << "&>(*Operands[OpIdx])." << Op.Class->RenderMethod


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