[clang] [analyzer] Fix crash analyzing _BitInt() in evalIntegralCast (PR #66782)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-static-analyzer-1

<details>
<summary>Changes</summary>

evalIntegralCast was using makeIntVal, and when _BitInt() types were introduced this exposed a crash in evalIntegralCast as a result.

Improve evalIntegralCast to use makeIntVal more efficiently to avoid the crash exposed by use of _BitInt.

This was caught with our internal randomized testing.

<src-root>/llvm/include/llvm/ADT/APInt.h:1510:
  int64_t llvm::APInt::getSExtValue() const: Assertion
  `getSignificantBits() <= 64 && "Too many bits for int64_t"' failed.a

...
 #<!-- -->9 <address> llvm::APInt::getSExtValue() const
  <src-root>/llvm/include/llvm/ADT/APInt.h:1510:5
  llvm::IntrusiveRefCntPtr<clang::ento::ProgramState const>,
  clang::ento::SVal, clang::QualType, clang::QualType)
  <src-root>/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp:607:24
  clang::Expr const*, clang::ento::ExplodedNode*, clang::ento::ExplodedNodeSet&)
  <src-root>/clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp:413:61
...

 Fixes: https://github.com/llvm/llvm-project/issues/61960

 Reviewed By: donat.nagy

---
Full diff: https://github.com/llvm/llvm-project/pull/66782.diff


2 Files Affected:

- (modified) clang/lib/StaticAnalyzer/Core/SValBuilder.cpp (+3-5) 
- (added) clang/test/Analysis/bitint-no-crash.c (+13) 


``````````diff
diff --git a/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp b/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
index 4fe828bdf7681fc..f827f43eaa7da67 100644
--- a/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
+++ b/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp
@@ -598,11 +598,9 @@ SVal SValBuilder::evalIntegralCast(ProgramStateRef state, SVal val,
   APSIntType ToType(getContext().getTypeSize(castTy),
                     castTy->isUnsignedIntegerType());
   llvm::APSInt ToTypeMax = ToType.getMaxValue();
-  NonLoc ToTypeMaxVal =
-      makeIntVal(ToTypeMax.isUnsigned() ? ToTypeMax.getZExtValue()
-                                        : ToTypeMax.getSExtValue(),
-                 castTy)
-          .castAs<NonLoc>();
+
+  NonLoc ToTypeMaxVal = makeIntVal(ToTypeMax);
+
   // Check the range of the symbol being casted against the maximum value of the
   // target type.
   NonLoc FromVal = val.castAs<NonLoc>();
diff --git a/clang/test/Analysis/bitint-no-crash.c b/clang/test/Analysis/bitint-no-crash.c
new file mode 100644
index 000000000000000..0a367fa930dc9b1
--- /dev/null
+++ b/clang/test/Analysis/bitint-no-crash.c
@@ -0,0 +1,13 @@
+ // RUN: %clang_analyze_cc1 -analyzer-checker=core \
+ // RUN:   -analyzer-checker=debug.ExprInspection \
+ // RUN:   -triple x86_64-pc-linux-gnu \
+ // RUN:   -verify %s
+
+// Don't crash when using _BitInt(). Pin to the x86_64 triple for now,
+// since not all architectures support _BitInt()
+// expected-no-diagnostics
+_BitInt(256) a;
+_BitInt(129) b;
+void c() {
+  b = a;
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/66782