TableGen: Change { } to only accept bits<n> entries when n == 1.

Prior to this change, it was legal to do something like

  bits<2> opc = { 0, 1 };
  bits<2> opc2 = { 1, 0 };
  bits<2> a = { opc, opc2 };

This involved silently dropping bits from opc and opc2 which is very hard to debug.

Now the above test would be an error.  Having tested with an assert, none of LLVM/clang was relying on this behaviour.

Thanks to Adam Nemet for the above test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215083 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/TableGen/Record.cpp b/lib/TableGen/Record.cpp
index cf8ef9bbf279f8db3dcd2ab1234047303fba798c..8267a36426118d32a2ec23e225d6a1178eb99bfd 100644 (file)
--- a/lib/TableGen/Record.cpp
+++ b/lib/TableGen/Record.cpp
@@ -114,8 +114,11 @@ Init *BitRecTy::convertValue(IntInit *II) {
 
 Init *BitRecTy::convertValue(TypedInit *VI) {
   RecTy *Ty = VI->getType();
-  if (isa<BitRecTy>(Ty) || isa<BitsRecTy>(Ty) || isa<IntRecTy>(Ty))
+  if (isa<BitRecTy>(Ty))
     return VI;  // Accept variable if it is already of bit type!
+  if (auto *BitsTy = dyn_cast<BitsRecTy>(Ty))
+    // Accept only bits<1> expression.
+    return BitsTy->getNumBits() == 1 ? VI : nullptr;
   return nullptr;
 }
 

diff --git a/test/TableGen/BitsInit.td b/test/TableGen/BitsInit.td
new file mode 100644 (file)
index 0000000..28fd319
--- /dev/null
+++ b/test/TableGen/BitsInit.td
@@ -0,0 +1,22 @@
+
+// RUN: not llvm-tblgen %s 2>&1 > %t
+// RUN: FileCheck %s < %t
+
+def a {
+  bits<2> opc = { 0, 1 };
+  bits<2> opc2 = { 1, 0 };
+  bits<1> opc3 = { 1 };
+  bits<2> a = { opc, opc2 }; // error!
+  bits<2> b = { opc{0}, opc2{0} };
+  bits<2> c = { opc{1}, opc2{1} };
+  bits<2> c = { opc3{0}, opc3 };
+}
+
+// CHECK: def a {
+// CHECK:   bits<2> opc = { 0, 1 };
+// CHECK:   bits<2> opc2 = { 1, 0 };
+// CHECK:   bits<1> opc3 = { 1 };
+// CHECK:   bits<2> a = { ?, ? };
+// CHECK:   bits<2> b = { 1, 0 };
+// CHECK:   bits<2> c = { 1, 1 };
+// CHECK: }