[globalisel][tablegen] Predicates should start from GIPFP_Invalid+1 not GIPFP_Invalid

This fixes a warning when there are zero defined predicates and also fixes an
unnoticed bug where the first predicate in the table was unusable.

llvm-svn: 311684

2 files changed, 6 insertions, 3 deletions

diff --git a/llvm/test/TableGen/GlobalISelEmitter.td b/llvm/test/TableGen/GlobalISelEmitter.td
index ddfb4f8744a..4364f8645b8 100644
--- a/llvm/test/TableGen/GlobalISelEmitter.td
+++ b/llvm/test/TableGen/GlobalISelEmitter.td
@@ -111,10 +111,11 @@ def HasC : Predicate<"Subtarget->hasC()"> { let RecomputePerFunction = 1; }
 
 // CHECK-LABEL: // PatFrag predicates.
 // CHECK-NEXT:  enum {
-// CHECK-NEXT:    GIPFP_Predicate_simm8 = GIPFP_Invalid,
+// CHECK-NEXT:    GIPFP_Predicate_simm8 = GIPFP_Invalid + 1,
 // CHECK-NEXT:  };
 // CHECK-NEXT:  static bool Predicate_simm8(int64_t Imm) { return isInt<8>(Imm);   }
 // CHECK-NEXT:  static InstructionSelector::ImmediatePredicateFn ImmPredicateFns[] = {
+// CHECK-NEXT:    nullptr,
 // CHECK-NEXT:    Predicate_simm8,
 // CHECK-NEXT:  };
 
diff --git a/llvm/utils/TableGen/GlobalISelEmitter.cpp b/llvm/utils/TableGen/GlobalISelEmitter.cpp
index 17898beb7de..3402c496c8d 100644
--- a/llvm/utils/TableGen/GlobalISelEmitter.cpp
+++ b/llvm/utils/TableGen/GlobalISelEmitter.cpp
@@ -2731,7 +2731,7 @@ void GlobalISelEmitter::run(raw_ostream &OS) {
   {
     OS << "// PatFrag predicates.\n"
        << "enum {\n";
-    StringRef EnumeratorSeparator = " = GIPFP_Invalid,\n";
+    StringRef EnumeratorSeparator = " = GIPFP_Invalid + 1,\n";
     for (const auto *Record : RK.getAllDerivedDefinitions("PatFrag")) {
       if (!Record->getValueAsString("ImmediateCode").empty()) {
         OS << "  GIPFP_Predicate_" << Record->getName() << EnumeratorSeparator;
@@ -2744,7 +2744,9 @@ void GlobalISelEmitter::run(raw_ostream &OS) {
     if (!Record->getValueAsString("ImmediateCode").empty())
       OS << "  static bool Predicate_" << Record->getName() << "(int64_t Imm) {"
          << Record->getValueAsString("ImmediateCode") << "  }\n";
-  OS << "static InstructionSelector::ImmediatePredicateFn ImmPredicateFns[] = {\n";
+  OS << "static InstructionSelector::ImmediatePredicateFn ImmPredicateFns[] = "
+        "{\n"
+     << "  nullptr,\n";
   for (const auto *Record : RK.getAllDerivedDefinitions("PatFrag"))
     if (!Record->getValueAsString("ImmediateCode").empty())
       OS << "  Predicate_" << Record->getName() << ",\n";