From 6551a7dcb014b972909d340fab34f8b282722de2 Mon Sep 17 00:00:00 2001
From: Martin Kinkelin <mkinkelin@symmetryinvestments.com>
Date: Sun, 18 Aug 2024 15:20:16 +0200
Subject: [PATCH] Tighten checks for IR aggregate sizes

---
 ir/iraggr.cpp             |  7 ++++++-
 ir/irtypeclass.cpp        |  6 ++++++
 ir/irtypestruct.cpp       |  6 ++++++
 tests/compilable/gh4734.d | 20 ++++++++++++++++++++
 4 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 tests/compilable/gh4734.d

diff --git a/ir/iraggr.cpp b/ir/iraggr.cpp
index faca04f25c4..a19867af544 100644
--- a/ir/iraggr.cpp
+++ b/ir/iraggr.cpp
@@ -11,6 +11,7 @@
 
 #include "dmd/aggregate.h"
 #include "dmd/declaration.h"
+#include "dmd/errors.h"
 #include "dmd/expression.h"
 #include "dmd/identifier.h"
 #include "dmd/init.h"
@@ -217,8 +218,12 @@ IrAggr::createInitializerConstant(const VarInitMap &explicitInitializers) {
 
   // tail padding?
   const size_t structsize = aggrdecl->size(Loc());
-  if (offset < structsize)
+  if (offset < structsize) {
     add_zeros(constants, offset, structsize);
+  } else if (offset > structsize) {
+    error(Loc(), "ICE: IR aggregate constant size exceeds the frontend size");
+    fatal();
+  }
 
   // get LL field types
   llvm::SmallVector<llvm::Type *, 16> types;
diff --git a/ir/irtypeclass.cpp b/ir/irtypeclass.cpp
index e29b7460706..087c3b55919 100644
--- a/ir/irtypeclass.cpp
+++ b/ir/irtypeclass.cpp
@@ -12,6 +12,7 @@
 #include "dmd/aggregate.h"
 #include "dmd/declaration.h"
 #include "dmd/dsymbol.h"
+#include "dmd/errors.h"
 #include "dmd/mtype.h"
 #include "dmd/target.h"
 #include "dmd/template.h"
@@ -98,6 +99,11 @@ IrTypeClass *IrTypeClass::get(ClassDeclaration *cd) {
   isaStruct(t->type)->setBody(builder.defaultTypes(), builder.isPacked());
   t->varGEPIndices = builder.varGEPIndices();
 
+  if (instanceSize && getTypeAllocSize(t->type) != instanceSize) {
+    error(cd->loc, "ICE: class IR size does not match the frontend size");
+    fatal();
+  }
+
   IF_LOG Logger::cout() << "class type: " << *t->type << std::endl;
 
   return t;
diff --git a/ir/irtypestruct.cpp b/ir/irtypestruct.cpp
index ccbb5b9514c..fba984498a1 100644
--- a/ir/irtypestruct.cpp
+++ b/ir/irtypestruct.cpp
@@ -11,6 +11,7 @@
 
 #include "dmd/aggregate.h"
 #include "dmd/declaration.h"
+#include "dmd/errors.h"
 #include "dmd/init.h"
 #include "dmd/mtype.h"
 #include "dmd/template.h"
@@ -91,6 +92,11 @@ IrTypeStruct *IrTypeStruct::get(StructDeclaration *sd) {
     builder.addTailPadding(sd->structsize);
     isaStruct(t->type)->setBody(builder.defaultTypes(), builder.isPacked());
     t->varGEPIndices = builder.varGEPIndices();
+
+    if (getTypeAllocSize(t->type) != sd->structsize) {
+      error(sd->loc, "ICE: struct IR size does not match the frontend size");
+      fatal();
+    }
   }
 
   IF_LOG Logger::cout() << "final struct type: " << *t->type << std::endl;
diff --git a/tests/compilable/gh4734.d b/tests/compilable/gh4734.d
new file mode 100644
index 00000000000..49656e86077
--- /dev/null
+++ b/tests/compilable/gh4734.d
@@ -0,0 +1,20 @@
+// RUN: %ldc -c %s
+
+align(1) struct Item {
+    KV v;
+    uint i;
+}
+
+struct KV {
+    align(1) S* s;
+    uint k;
+}
+
+struct S {
+    Table table;
+}
+
+struct Table {
+    char a;
+    Item v;
+}