[clang] [analyzer] Retain address space information in getElementRegion (PR #151370)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat created https://github.com/llvm/llvm-project/pull/151370

The factory method `MemRegionManager::getElementRegion()` is the main way of constructing `ElementRegion` objects, which are widespread in the analysis and may represent array elements (as lvalues), pointer arithmetics and type conversions.

This factory method used to strip all qualifiers from the type associated with the element (after canonicalizing it), but the address space qualifier can affect the size of a pointer type, so stripping it caused an assertion failure (in `evalBinOpLL`):

clang: clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp:785: void assertEqualBitWidths(clang::ento::ProgramStateRef, clang::ento::Loc, clang::ento::Loc): Assertion `RhsBitwidth == LhsBitwidth && "RhsLoc and LhsLoc bitwidth must be same!"' failed.

>From 690e311be23ef506c1316d076991d3b557718474 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Don=C3=A1t=20Nagy?= <donat.nagy at ericsson.com>
Date: Wed, 30 Jul 2025 19:40:10 +0200
Subject: [PATCH] [analyzer] Retain address space information in
 getElementRegion

The factory method `MemRegionManager::getElementRegion()` is the main
way of constructing `ElementRegion` objects, which are widespread in the
analysis and may represent array elements (as lvalues), pointer
arithmetics and type conversions.

This factory method used to strip all qualifiers from the type
associated with the element (after canonicalizing it), but the address
space qualifier can affect the size of a pointer type, so stripping it
caused an assertion failure (in `evalBinOpLL`):

clang: clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp:785:
void assertEqualBitWidths(clang::ento::ProgramStateRef, clang::ento::Loc,
clang::ento::Loc): Assertion `RhsBitwidth == LhsBitwidth &&
"RhsLoc and LhsLoc bitwidth must be same!"' failed.

Co-authored-by: Vince Bridgers <vince.a.bridgers at ericsson.com>
---
 clang/lib/StaticAnalyzer/Core/MemRegion.cpp        | 10 ++++++++++
 clang/test/Analysis/element-region-address-space.c | 11 +++++++++++
 2 files changed, 21 insertions(+)
 create mode 100644 clang/test/Analysis/element-region-address-space.c

diff --git a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
index 3e68373028b10..0058a0ddfb0df 100644
--- a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
+++ b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
@@ -1219,6 +1219,16 @@ MemRegionManager::getElementRegion(QualType elementType, NonLoc Idx,
                                    const ASTContext &Ctx) {
   QualType T = Ctx.getCanonicalType(elementType).getUnqualifiedType();
 
+  // The address space must be preserved because some target-specific address
+  // spaces influence the size of the pointer value which is represented by the
+  // element region.
+  LangAS AS = elementType.getAddressSpace();
+  if (AS != LangAS::Default) {
+    Qualifiers Quals;
+    Quals.setAddressSpace(AS);
+    T = Ctx.getQualifiedType(T, Quals);
+  }
+
   llvm::FoldingSetNodeID ID;
   ElementRegion::ProfileRegion(ID, T, Idx, superRegion);
 
diff --git a/clang/test/Analysis/element-region-address-space.c b/clang/test/Analysis/element-region-address-space.c
new file mode 100644
index 0000000000000..fddc1bb840231
--- /dev/null
+++ b/clang/test/Analysis/element-region-address-space.c
@@ -0,0 +1,11 @@
+// RUN: %clang_analyze_cc1 -triple amdgcn-unknown-unknown \
+// RUN: -analyzer-checker=core,unix.Malloc -verify %s
+
+// expected-no-diagnostics
+//
+// By default, pointers are 64-bits.
+#define ADDRESS_SPACE_32BITS __attribute__((address_space(3)))
+
+int test(ADDRESS_SPACE_32BITS int *p, ADDRESS_SPACE_32BITS void *q) {
+  return p == q;
+}