Reapply [Verifier] Sanity check alloca size against DILocalVariable fragment size

Reapply now that generation of incorrect debuginfo for FnDef
in rustc has been fixed.

-----

Add a check that the DILocalVariable fragment size in dbg.declare
does not exceed the size of the alloca.

This would have caught the invalid debuginfo regenerated by rustc
in https://github.com/llvm/llvm-project/issues/64149.

Differential Revision: https://reviews.llvm.org/D158743

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 5a33284..188e4a4 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -6318,6 +6318,20 @@ void Verifier::visitDbgIntrinsic(StringRef Kind, DbgVariableIntrinsic &DII) {
   CheckDI(isType(Var->getRawType()), "invalid type ref", Var,
           Var->getRawType());
   verifyFnArgs(DII);
+
+  if (auto *Declare = dyn_cast<DbgDeclareInst>(&DII)) {
+    if (auto *Alloca = dyn_cast_or_null<AllocaInst>(Declare->getAddress())) {
+      DIExpression *Expr = Declare->getExpression();
+      std::optional<uint64_t> FragSize = Declare->getFragmentSizeInBits();
+      std::optional<TypeSize> AllocSize = Alloca->getAllocationSizeInBits(DL);
+      if (FragSize && AllocSize && !AllocSize->isScalable() &&
+          !Expr->isComplex()) {
+        CheckDI(*FragSize <= AllocSize->getFixedValue(),
+                "llvm.dbg.declare has larger fragment size than alloca size ",
+                &DII);
+      }
+    }
+  }
 }
 
 void Verifier::visitDbgLabelIntrinsic(StringRef Kind, DbgLabelInst &DLI) {