Add the ability to use logical expressions for capability attributes. This is to allow requirements to be expressed not just in terms of lists, but in terms of logical expressions. Eg)

void foo(void) __attribute__((requires_capability((FlightControl || Worker) && !Logger)));

This is WIP code.

llvm-svn: 208439

1 files changed, 112 insertions, 0 deletions

diff --git a/clang/lib/Analysis/ThreadSafetyLogical.cpp b/clang/lib/Analysis/ThreadSafetyLogical.cpp
new file mode 100644
index 00000000000..51a80776e77
--- /dev/null
+++ b/clang/lib/Analysis/ThreadSafetyLogical.cpp
@@ -0,0 +1,112 @@
+//===- ThreadSafetyLogical.cpp ---------------------------------*- C++ --*-===//

+//

+//                     The LLVM Compiler Infrastructure

+//

+// This file is distributed under the University of Illinois Open Source

+// License. See LICENSE.TXT for details.

+//

+//===----------------------------------------------------------------------===//

+// This file defines a representation for logical expressions with SExpr leaves

+// that are used as part of fact-checking capability expressions.

+//===----------------------------------------------------------------------===//

+

+#include "clang/Analysis/Analyses/ThreadSafetyLogical.h"

+

+using namespace llvm;

+using namespace clang::threadSafety::lexpr;

+

+// Implication.  We implement De Morgan's Laws by maintaining LNeg and RNeg

+// to keep track of whether LHS and RHS are negated.

+static bool implies(const LExpr *LHS, bool LNeg, const LExpr *RHS, bool RNeg) {

+  // In comments below, we write => for implication.

+

+  // Calculates the logical AND implication operator.

+  const auto LeftAndOperator = [=](const BinOp *A) {

+    return implies(A->left(), LNeg, RHS, RNeg) &&

+           implies(A->right(), LNeg, RHS, RNeg);

+  };

+  const auto RightAndOperator = [=](const BinOp *A) {

+    return implies(LHS, LNeg, A->left(), RNeg) &&

+           implies(LHS, LNeg, A->right(), RNeg);

+  };

+

+  // Calculates the logical OR implication operator.

+  const auto LeftOrOperator = [=](const BinOp *A) {

+    return implies(A->left(), LNeg, RHS, RNeg) ||

+           implies(A->right(), LNeg, RHS, RNeg);

+  };

+  const auto RightOrOperator = [=](const BinOp *A) {

+    return implies(LHS, LNeg, A->left(), RNeg) ||

+           implies(LHS, LNeg, A->right(), RNeg);

+  };

+

+  // Recurse on right.

+  switch (RHS->kind()) {

+  case LExpr::And:

+    // When performing right recursion:

+    //   C => A & B  [if]  C => A and C => B

+    // When performing right recursion (negated):

+    //   C => !(A & B)  [if]  C => !A | !B  [===]  C => !A or C => !B

+    return RNeg ? RightOrOperator(cast<And>(RHS))

+                : RightAndOperator(cast<And>(RHS));

+  case LExpr::Or:

+    // When performing right recursion:

+    //   C => (A | B)  [if]  C => A or C => B

+    // When performing right recursion (negated):

+    //   C => !(A | B)  [if]  C => !A & !B  [===]  C => !A and C => !B

+    return RNeg ? RightAndOperator(cast<Or>(RHS))

+                : RightOrOperator(cast<Or>(RHS));

+  case LExpr::Not:

+    // Note that C => !A is very different from !(C => A). It would be incorrect

+    // to return !implies(LHS, RHS).

+    return implies(LHS, LNeg, cast<Not>(RHS)->exp(), !RNeg);

+  case LExpr::Terminal:

+    // After reaching the terminal, it's time to recurse on the left.

+    break;

+  }

+

+  // RHS is now a terminal.  Recurse on Left.

+  switch (LHS->kind()) {

+  case LExpr::And:

+    // When performing left recursion:

+    //   A & B => C  [if]  A => C or B => C

+    // When performing left recursion (negated):

+    //   !(A & B) => C  [if]  !A | !B => C  [===]  !A => C and !B => C

+    return LNeg ? LeftAndOperator(cast<And>(LHS))

+                : LeftOrOperator(cast<And>(LHS));

+  case LExpr::Or:

+    // When performing left recursion:

+    //   A | B => C  [if]  A => C and B => C

+    // When performing left recursion (negated):

+    //   !(A | B) => C  [if]  !A & !B => C  [===]  !A => C or !B => C

+    return LNeg ? LeftOrOperator(cast<Or>(LHS))

+                : LeftAndOperator(cast<Or>(LHS));

+  case LExpr::Not:

+    // Note that A => !C is very different from !(A => C). It would be incorrect

+    // to return !implies(LHS, RHS).

+    return implies(cast<Not>(LHS)->exp(), !LNeg, RHS, RNeg);

+  case LExpr::Terminal:

+    // After reaching the terminal, it's time to perform identity comparisons.

+    break;

+  }

+

+  // A => A

+  // !A => !A

+  if (LNeg != RNeg)

+    return false;

+

+  // FIXME -- this should compare SExprs for equality, not pointer equality.

+  return cast<Terminal>(LHS)->expr() == cast<Terminal>(RHS)->expr();

+}

+

+namespace clang {

+namespace threadSafety {

+namespace lexpr {

+

+bool implies(const LExpr *LHS, const LExpr *RHS) {

+  // Start out by assuming that LHS and RHS are not negated.

+  return ::implies(LHS, false, RHS, false);

+}

+}

+}

+}