Adds a batch of C tests that have been found to cover several hundred lines of Clang/LLVM that are not covered by the unit and regression tests of the main LLVM project, nor by the test suite when run with the -O3 configuration.

[arindamsharma8]

Summary

The tests were originally generated using our fuzzer, and were then reduced
using C-Reduce. These test have been checked for undefined behaviour-freedom
using Frama-C and code sanitisers, manually checked to eliminate
implementation-defined behaviour.

Most of the new coverage achieved by these 8 C code tests is in:
llvm-project/clang/lib/AST (2 testcases)
llvm-project/clang/lib/Sema (2 testcase)
llvm-project/llvm/lib/Analysis (1 testcase)
llvm-project/llvm/lib/CodeGen (4 testcases)
llvm-project/llvm/lib/Transforms(1 testcase)

[arindamsharma8]

Connected to https://reviews.llvm.org/D142638.

SingleSource/UnitTests/testcase-CodeGen-1.c

+// COVERAGE: llvm-project/llvm/lib/Analysis/InlineCost.cpp (1 new functions)
+// COVERAGE: llvm-project/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp (2 new functions)
+// COVERAGE: llvm-project/llvm/lib/CodeGen/TargetLoweringBase.cpp (2 new functions)
+extern void abort();
+#ifndef __SIZEOF_INT128__
+#define __int128 long long // Appears in test case of pr61375.c
+#endif
+unsigned __int128 a;
+void b() { a = (double)a + 0; }
+int main() {
+  b();
+  if (a)
+    abort();
+  return 0;
+}

SingleSource/UnitTests/testcase-CodeGen-1.reference_output

+exit 0

SingleSource/UnitTests/testcase-CodeGen-2.c

+// COVERAGE: llvm-project/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp (1 new functions)
+// COVERAGE: llvm-project/llvm/lib/CodeGen/TargetLoweringBase.cpp (1 new functions)
+extern void abort();
+#ifndef __SIZEOF_INT128__
+#define __int128 long long // Appears in test case of pr61375.c
+#endif
+float a;
+int main() {
+  __int128 b = a;
+  if (b + (double)10)
+    ++b;
+  while (b != 1)
+    abort();
+  return 0;
+}

SingleSource/UnitTests/testcase-CodeGen-2.reference_output

+exit 0

SingleSource/UnitTests/testcase-CodeGen-3.c

+// COVERAGE: llvm-project/clang/lib/AST/ExprConstant.cpp (1 new functions)
+// COVERAGE: llvm-project/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp (1 new functions)
+// COVERAGE: llvm-project/llvm/lib/CodeGen/TargetLoweringBase.cpp (1 new functions)
+#include "stdio.h"
+#ifdef __SIZEOF_INT128__
+typedef __int128 L;  // Appears in pr49218.c test case
+#else
+typedef long long L;
+#endif
+float f;
+int main() {
+  L i = f;
+  if (i <= 10 +
+                41 * +((long)(((int)10) >> ((int)10))) *
+                    ((long)(((int)(i)) % ((int)10))) -
+                ((long)(((double)(i)) + ((double)10))) -
+                ((long)(((int)10) ^ ((int)10))))
+    do {
+      ++i;
+      printf("%lld", (long long) i);
+    } while (i != 11);
+  return 0;
+}

SingleSource/UnitTests/testcase-CodeGen-3.reference_output

[phone]exit 0

SingleSource/UnitTests/testcase-Float2Int.c

+// COVERAGE: llvm-project/llvm/lib/Transforms/Scalar/Float2Int.cpp (1 new functions)
+#include "stdio.h"
+char b = 32;
+int main() {
+  for (b = ((long)(((double)(b)) * ((double)(b)))); b >= -29; b--)
+    printf("%d", (int)b);
+  printf("\n");
+  return 0;
+}

SingleSource/UnitTests/testcase-Float2Int.reference_output

+0-1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18-19-20-21-22-23-24-25-26-27-28-29
+exit 0

SingleSource/UnitTests/testcase-SelectionDAG.c

+// COVERAGE: llvm-project/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (1 new functions)
+int a;
+int main() {
+  int b = 0;
+  for (; a; a = 2 - (0 | a)) {
+    b++;
+    if (b <= 4)
+      continue;
+    break;
+  }
+  return b;
+}

SingleSource/UnitTests/testcase-SelectionDAG.reference_output

+exit 9

SingleSource/UnitTests/testcase-SimplifyIndVar.c

+// COVERAGE: llvm-project/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp (1 new functions)
+short a;
+void foo() {
+  if (a < 0)
+    __builtin_abort();
+}
+int main() {
+  int b = 8;
+  while (a++ <= 0) {
+    b++;
+    if (b <= 0 + 1 * (b % 40) * (double)0 - 0 - 0 -
+                 ((040) * ((b))) * ((((int)(b)) << ((int)(b)))) +
+                 ((long)(((double)(b)) - ((double)0))) +
+                 ((long)(((double)0) - ((double)(b)))) -
+                 ((short)(((double)(b)) - ((double)0))) +
+                 ((long)(((int)0) ^ ((int)0))) -
+                 ((long)(((double)(b)) + ((double)0))))
+      break;
+  }
+  foo();
+  if (b != 9)
+    __builtin_abort();
+  return 0;
+}

SingleSource/UnitTests/testcase-SimplifyIndVar.reference_output

+exit 0

SingleSource/UnitTests/testcase-StmtPrinter.c

+// COVERAGE: llvm-project/clang/lib/AST/StmtPrinter.cpp (1 new functions)
+char a, b, g, h, i;
+short c, d, k;
+int e, f, j;
+void l() {
+  k = i > 0 || d > 1 >> d << i;
+  for (; j; j++)
+    h = c < 0 || h || c << (8 + 2 - (long)0);
+  g = f + 1 + 2 * 0 * 0;
+  for (; f < 1; f = 1 + 2 - 0)
+    b = a + 1 + 2 * 0;
+  if (b == 0)
+    __builtin_abort();
+}
+int main() {
+  for (; e < 1; e++)
+    l();
+  if (h == 0)
+    __builtin_abort();
+  return 0;
+}

SingleSource/UnitTests/testcase-StmtPrinter.reference_output

+exit 0

SingleSource/UnitTests/testcase-clang-lib-1.c

+// COVERAGE: llvm-project/clang/include/clang/AST/EvaluatedExprVisitor.h (1 new functions)
+// COVERAGE: llvm-project/clang/lib/AST/ComputeDependence.cpp (1 new functions)
+// COVERAGE: llvm-project/clang/lib/AST/Expr.cpp (2 new functions)
+// COVERAGE: llvm-project/clang/lib/CodeGen/CGExprScalar.cpp (1 new functions)
+// COVERAGE: llvm-project/clang/lib/Parse/ParseExpr.cpp (1 new functions)
+// COVERAGE: llvm-project/clang/lib/Sema/SemaExpr.cpp (2 new functions)
+#include <stdio.h>
+typedef int (*fptr)(int);
+int foo(int i) { return i; }
+int main() {
+  int b = _Generic(foo, fptr : 3, int : 4);
+  printf("%d\n", b);
+  return 0;
+}

SingleSource/UnitTests/testcase-clang-lib-1.reference_output

+3
+exit 0