[analyzer] Fix crash analyzing _BitInt() in evalIntegralCast

[vabridgers]

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

This is a reapply of a previous patch that failed post merge on the arm buildbots, because arm cannot handle large
BitInts. Pinning the triple for the testcase solves that problem.

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

This was caught with our internal randomized testing.

/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

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

Fixes: #61960

Reviewed By: donat.nagy

[llvmbot]

@llvm/pr-subscribers-clang

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

Changes

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: #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 --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;
+}

[NagyDonat]

This commit was reverted once (see discussion on earlier pull request #65887), because the buildbot linaro-clang-armv8-quick couldn't handle the large _BitInt()s in the testcase. Pinning to the x86_64 triple solves this problem, so it's safe to resubmit the commit now.