[TableGen] Diagnose negative !listsplat count

[jayfoad]

No description provided.

[llvmbot]

@llvm/pr-subscribers-tablegen

Author: Jay Foad (jayfoad)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/163152.diff

2 Files Affected:

• (modified) llvm/lib/TableGen/Record.cpp (+5-3)
• (modified) llvm/test/TableGen/listsplat.td (+6)

diff --git a/llvm/lib/TableGen/Record.cpp b/llvm/lib/TableGen/Record.cpp
index 2ea3a24bb8eb2..cd64b227094a2 100644
--- a/llvm/lib/TableGen/Record.cpp
+++ b/llvm/lib/TableGen/Record.cpp
@@ -1363,9 +1363,11 @@ const Init *BinOpInit::Fold(const Record *CurRec) const {
   }
   case LISTSPLAT: {
     const auto *Value = dyn_cast<TypedInit>(LHS);
-    const auto *Size = dyn_cast<IntInit>(RHS);
-    if (Value && Size) {
-      SmallVector<const Init *, 8> Args(Size->getValue(), Value);
+    const auto *Count = dyn_cast<IntInit>(RHS);
+    if (Value && Count) {
+      if (Count->getValue() < 0)
+      PrintFatalError(Twine("!listsplat count ") + Count->getAsString() + " is negative");
+      SmallVector<const Init *, 8> Args(Count->getValue(), Value);
       return ListInit::get(Args, Value->getType());
     }
     break;
diff --git a/llvm/test/TableGen/listsplat.td b/llvm/test/TableGen/listsplat.td
index 5a93a4c722c05..43803d6e6fbe3 100644
--- a/llvm/test/TableGen/listsplat.td
+++ b/llvm/test/TableGen/listsplat.td
@@ -1,4 +1,5 @@
 // RUN: llvm-tblgen %s | FileCheck %s
+// RUN: not llvm-tblgen -DERROR1 %s 2>&1 | FileCheck --check-prefix=ERROR1 %s
 
 // CHECK: ------------- Classes -----------------
 // CHECK-NEXT: class X<int X:a = ?, int X:b = ?> {
@@ -73,3 +74,8 @@ def DYa1 : Y<"a", 1>;
 def DYa2 : Y<"a", 2>;
 
 def DZ : X<42, !size([1, 2, 3])>;
+
+#ifdef ERROR1
+// ERROR1: !listsplat count -1 is negative
+defvar E = !listsplat("", -1);
+#endif

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[jayfoad]

Without this fix the failure looks like:

LLVM ERROR: SmallVector unable to grow. Requested capacity (18446744073709551615) is larger than maximum value for size type (4294967295)
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and instructions to reproduce the bug.

[Sisyph]

Definitely an improved error message! LGTM