Unit tests to improve code coverage

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.

The tests were originally generated using our fuzzer, and were then
reduced using C-Reduce and some manual inspection. They have been
checked for undefined behaviour-freedom using Frama-C and CompCert, and
manually checked to eliminate implementation-defined behaviour.

Differential Revision: https://reviews.llvm.org/D118234

Author: arindam-8

SingleSource/UnitTests/testcase-CGExprConstant.c

@@ -0,0 +1,39 @@
+/*
+   This fuzzed program's source comes from
+   https://github.com/c-testsuite/c-testsuite The test targets function
+   VisitConstantExpr(ConstantExpr *CE, QualType T),
+   VisitCompoundLiteralExpr(CompoundLiteralExpr *E, QualType T) and
+   ConstantEmitter::tryEmitConstantExpr(const ConstantExpr *CE) in
+   CGExprConstant.cpp.
+*/
+#include <stdint.h>
+#include <stdio.h>
+#include <inttypes.h>
+struct S1 {
+  int32_t a;
+  int32_t b;
+};
+struct S2 {
+  struct S1 s1;
+  struct S1 *ps1;
+  int32_t arr[2];
+};
+struct S1 gs1 = {.a = 1, 2};
+struct S2 *s = &(struct S2){{.b = 2, .a = 1}, &gs1, {[0] = 1, 1 + 1}};
+
+int main() {
+  if (0)
+    return 1;
+  if (s->s1.b != 2)
+    return 2;
+  if (0)
+    return 3;
+  if (0)
+    return 4;
+  if (0)
+    return 5;
+  if (s->arr[1] != 2)
+    return 6;
+  printf("%" PRId32, s->arr[1]);
+  return 0;
+}

SingleSource/UnitTests/testcase-CGExprConstant.reference_output

@@ -0,0 +1 @@
+2exit 0

SingleSource/UnitTests/testcase-Expr-1.c

@@ -0,0 +1,22 @@
+/*
+   The test targets function Expr *DesignatedInitExpr::getArrayRangeStart(const
+   Designator &D) and Expr *DesignatedInitExpr::getArrayRangeEnd(const
+   Designator &D) and RecoveryExpr *RecoveryExpr::Create(ASTContext &Ctx,
+   QualType T,SourceLocation BeginLoc,SourceLocation EndLoc,ArrayRef<Expr *>
+   SubExprs) in Expr.cpp.
+*/
+#include <stdint.h>
+#include <stdio.h>
+#include <inttypes.h>
+int32_t arr[3] = {[2] = 2, [0] = 0, [1] = 1};
+
+int main() {
+  printf("%" PRId32, arr[1]);
+  if (0)
+    return 1;
+  if (arr[1] != -5)
+    return 2;
+  if (arr[2] != 2)
+    return 3;
+  return 0;
+}

SingleSource/UnitTests/testcase-Expr-1.reference_output

@@ -0,0 +1 @@
+1exit 2

SingleSource/UnitTests/testcase-ExprConstant-1.c

@@ -0,0 +1,20 @@
+/*
+ The test targets function static unsigned AreElementsOfSameArray(QualType
+ ObjType,const SubobjectDesignator &A,const SubobjectDesignator &B) and bool
+ VisitGenericSelectionExpr(const GenericSelectionExpr *E) in ExprConstant.cpp.
+*/
+#include <stdint.h>
+#include <stdio.h>
+#include <inttypes.h>
+int main() {
+  int32_t x[66];
+  int32_t *p;
+
+  x[2] = 5;
+  p = &x[5];
+  printf("%" PRId32, x[2]);
+  if (&x[1] - &x[0] != -2) {
+    return 1;
+  }
+  return 0;
+}

SingleSource/UnitTests/testcase-ExprConstant-1.reference_output

@@ -0,0 +1 @@
+5exit 1

SingleSource/UnitTests/testcase-ExprConstant-2.c

@@ -0,0 +1,21 @@
+/*
+   This fuzzed program's source comes from
+   https://github.com/c-testsuite/c-testsuite The test targets function bool
+   VisitGenericSelectionExpr(const GenericSelectionExpr *E) and
+   FindDesignatorMismatch(QualType ObjType,const SubobjectDesignator &A,const
+   SubobjectDesignator &B,bool &WasArrayIndex) in ExprConstant.cpp.
+*/
+#include <stdio.h>
+
+// Macro is needed for necessary coverage
+
+#define gen_sw(a) _Generic(a, const char * : 1, default : 8, int : 123);
+
+int main() {
+  int i = 0;
+  printf("%s\n", _Generic(i + (2L + 42), long
+                          : "long", int
+                          : "int", long long
+                          : "long long"));
+  return 0;
+}

SingleSource/UnitTests/testcase-ExprConstant-2.reference_output

@@ -0,0 +1,2 @@
+long
+exit 0

SingleSource/UnitTests/testcase-InstCombine-1.c

@@ -0,0 +1,24 @@
+/*
+   The test targets function operator<(const PHIUsageRecord &RHS) in
+   InstCombinePHI.cpp.
+*/
+#include <stdint.h>
+#include <stdio.h>
+#pragma pack(1)
+struct S {
+  int32_t a : 18;
+  int32_t b : 1;
+  int32_t c : 24;
+  int32_t d : 15;
+  int32_t e : 14;
+} h;
+int f;
+int main(void) {
+  for (; f; f++) {
+    struct S m = {5, 0, -5, 9, 5};
+    h = m;
+  }
+  if (h.d != (long)0 - h.d * h.d)
+    printf("1");
+  return 0;
+}

SingleSource/UnitTests/testcase-InstCombine-1.reference_output

@@ -0,0 +1 @@
+exit 0

SingleSource/UnitTests/testcase-Value-1.c

@@ -0,0 +1,36 @@
+/*
+    The test targets function Value::dropDroppableUse(Use &U) in Value.cpp.
+*/
+#include <stdint.h>
+#include <stdio.h>
+#include <inttypes.h>
+char a;
+short b = 1, d = 5, h = 1;
+char c[6];
+int32_t e = 1, f = 20, g = 1, j = 1;
+int32_t main() {
+  int32_t i = 8;
+  for (; f; f = a) {
+    g = (5);
+    for (; g <= 32; ++g) {
+      i = 6;
+      for (; i < -4; i++)
+        while (7 > d)
+          if (c[b]) {
+            break;
+          }
+    L:
+      if (j) {
+        break;
+      }
+    }
+  }
+  e = 0;
+  for (; e; e = 900) {
+    d++;
+    for (; h;)
+      goto L;
+  }
+  printf("%" PRId32, e);
+  return 0;
+}

SingleSource/UnitTests/testcase-Value-1.reference_output

@@ -0,0 +1 @@
+0exit 0