[analyzer] Fix crash exposed by D140059

[vabridgers]

Summary

Change https://reviews.llvm.org/D140059 exposed the following crash in
Z3Solver, where bit widths were not checked consistently with that
change. This change makes the check consistent, and fixes the crash.

clang: <root>/llvm/include/llvm/ADT/APSInt.h:99:
  int64_t llvm::APSInt::getExtValue() const: Assertion
  `isRepresentableByInt64() && "Too many bits for int64_t"' failed.
...
Stack dump:
0. Program arguments: clang -cc1 -internal-isystem <root>/lib/clang/16/include
  -nostdsysteminc -analyze -analyzer-checker=core,unix.Malloc,debug.ExprInspection
  -analyzer-config crosscheck-with-z3=true -verify reproducer.c

 #0 0x00000000045b3476 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int)
  <root>/llvm/lib/Support/Unix/Signals.inc:567:22
 #1 0x00000000045b3862 PrintStackTraceSignalHandler(void*)
  <root>/llvm/lib/Support/Unix/Signals.inc:641:1
 #2 0x00000000045b14a5 llvm::sys::RunSignalHandlers()
  <root>/llvm/lib/Support/Signals.cpp:104:20
 #3 0x00000000045b2eb4 SignalHandler(int)
  <root>/llvm/lib/Support/Unix/Signals.inc:412:1
 ...
 #9 0x0000000004be2eb3 llvm::APSInt::getExtValue() const
  <root>/llvm/include/llvm/ADT/APSInt.h:99:5
  <root>/llvm/lib/Support/Z3Solver.cpp:740:53
  clang::ASTContext&, clang::ento::SymExpr const*, llvm::APSInt const&, llvm::APSInt const&, bool)
  <root>/clang/include/clang/StaticAnalyzer/Core/PathSensitive/SMTConv.h:552:61

[steakhal]

I would not mind less artificial-looking test code, but I'll let you decide if you want to make action about it.

Have you thought about the rest of the callsites of getBitWidth()? Are they also vulnerable to similar bugs?

[steakhal]

I'm backporting this to clang-16.
https://github.com/llvm/llvm-project/issues/61149

clang/test/Analysis/z3-crosscheck.c

void floatUnaryLNotInEq(int h, int l) {
   int j;
   clang_analyzer_dump(!(float)h); // expected-warning{{Unknown}}
   clang_analyzer_dump((float)l); // expected-warning-re {{(float) (reg_${{[0-9]+}}<int l>)}}
   if ((!(float)h) != (float)l) {  // should not crash
     j += 10;
     // expected-warning@-1{{garbage}}
   }
 }
+
+// don't crash, and also produce a core.CallAndMessage finding
+void a(int);
+typedef struct {
+  int b;
+} c;
+c *d;
+void e() {
+  (void)d->b;
+  int f;
+  a(f); // expected-warning {{1st function call argument is an uninitialized value [core.CallAndMessage]}}
+}

llvm/lib/Support/Z3Solver.cpp

SMTExprRef mkBoolean(const bool b) override {
     return newExprRef(Z3Expr(Context, b ? Z3_mk_true(Context.Context)
                                         : Z3_mk_false(Context.Context)));
   }
 
   SMTExprRef mkBitvector(const llvm::APSInt Int, unsigned BitWidth) override {
     const Z3_sort Z3Sort = toZ3Sort(*getBitvectorSort(BitWidth)).Sort;
 
     // Slow path, when 64 bits are not enough.
-    if (LLVM_UNLIKELY(Int.getBitWidth() > 64u)) {
+    if (LLVM_UNLIKELY(!Int.isRepresentableByInt64())) {
       SmallString<40> Buffer;
       Int.toString(Buffer, 10);
       return newExprRef(Z3Expr(
           Context, Z3_mk_numeral(Context.Context, Buffer.c_str(), Z3Sort)));
     }
 
     const int64_t BitReprAsSigned = Int.getExtValue();
     const uint64_t BitReprAsUnsigned =