[TableGen] Prevent invalid code generation when emitting AssemblerPredicate conditions.

Summary:
The loop which emits AssemblerPredicate conditions also links them together by emitting a '&&'.
If the 1st predicate is not an AssemblerPredicate, while the 2nd one is, nothing gets emitted for the 1st one, but we still emit the '&&' because of the 2nd predicate.
This generated code looks like "( && Cond2)" and is invalid.

Reviewers: dsanders

Reviewed By: dsanders

Subscribers: dsanders, llvm-commits

Differential Revision: http://reviews.llvm.org/D8294

llvm-svn: 234312

1 files changed, 31 insertions, 0 deletions

diff --git a/llvm/test/TableGen/AsmPredicateCondsEmission.td b/llvm/test/TableGen/AsmPredicateCondsEmission.td
new file mode 100644
index 00000000000..ba5898fbebd
--- /dev/null
+++ b/llvm/test/TableGen/AsmPredicateCondsEmission.td
@@ -0,0 +1,31 @@
+// RUN: llvm-tblgen -gen-disassembler -I %p/../../include %s | FileCheck %s
+
+// Check that we don't generate invalid code of the form "( && Cond2)" when
+// emitting AssemblerPredicate conditions. In the example below, the invalid
+// code would be: "return ( && (Bits & arch::AssemblerCondition2));".
+
+include "llvm/Target/Target.td"
+
+def archInstrInfo : InstrInfo { }
+
+def arch : Target {
+  let InstructionSet = archInstrInfo;
+}
+
+def Pred1 : Predicate<"Condition1">;
+def Pred2 : Predicate<"Condition2">,
+            AssemblerPredicate<"AssemblerCondition2">;
+
+def foo : Instruction {
+  let Size = 2;
+  let OutOperandList = (outs);
+  let InOperandList = (ins);
+  field bits<16> Inst;
+  let Inst = 0xAAAA;
+  let AsmString = "foo";
+  field bits<16> SoftFail = 0;
+  // This is the important bit:
+  let Predicates = [Pred1, Pred2];
+}
+
+// CHECK: return ((Bits & arch::AssemblerCondition2));