C++: Remove the C specific things in the Guards library.

github · Nov 20, 2024 · 93e78f5 · 93e78f5
1 parent 9787712
commit 93e78f5
Show file tree

Hide file tree

Showing 4 changed files with 5 additions and 1,017 deletions.
diff --git a/cpp/ql/lib/semmle/code/cpp/controlflow/IRGuards.qll b/cpp/ql/lib/semmle/code/cpp/controlflow/IRGuards.qll
@@ -911,55 +911,6 @@ private predicate simple_comparison_eq(
   value.(BooleanValue).getValue() = false
 }
 
-/**
- * Holds if `op` is an operand that is eventually used in a unary comparison
- * with a constant.
- */
-private predicate isRelevantUnaryComparisonOperand(Operand op) {
-  // Base case: `op` is an operand of a `CompareEQInstruction` or `CompareNEInstruction`,
-  // and the other operand is a constant.
-  exists(CompareInstruction eq, Instruction instr |
-    eq.hasOperands(op, instr.getAUse()) and
-    exists(int_value(instr))
-  |
-    eq instanceof CompareEQInstruction
-    or
-    eq instanceof CompareNEInstruction
-  )
-  or
-  // C doesn't have int-to-bool conversions, so `if(x)` will just generate:
-  // r2_1(glval<int>) = VariableAddress[x]
-  // r2_2(int)        = Load[x]                : &:r2_1, m1_6
-  // v2_3(void)       = ConditionalBranch      : r2_2
-  exists(ConditionalBranchInstruction branch | branch.getConditionOperand() = op)
-  or
-  // If `!x` is a relevant unary comparison then so is `x`.
-  exists(LogicalNotInstruction logicalNot |
-    isRelevantUnaryComparisonOperand(unique( | | logicalNot.getAUse())) and
-    logicalNot.getUnaryOperand() = op
-  )
-  or
-  // If `y` is a relevant unary comparison and `y = x` then so is `x`.
-  not op.isDefinitionInexact() and
-  exists(CopyInstruction copy |
-    isRelevantUnaryComparisonOperand(unique( | | copy.getAUse())) and
-    op = copy.getSourceValueOperand()
-  )
-  or
-  // If phi(x1, x2) is a relevant unary comparison then so are `x1` and `x2`.
-  not op.isDefinitionInexact() and
-  exists(PhiInstruction phi |
-    isRelevantUnaryComparisonOperand(unique( | | phi.getAUse())) and
-    op = phi.getAnInputOperand()
-  )
-  or
-  // If `__builtin_expect(x)` is a relevant unary comparison then so is `x`.
-  exists(BuiltinExpectCallInstruction call |
-    isRelevantUnaryComparisonOperand(unique( | | call.getAUse())) and
-    op = call.getConditionOperand()
-  )
-}
-
 /** Rearrange various simple comparisons into `op == k` form. */
 private predicate unary_simple_comparison_eq(
   ValueNumber test, Operand op, int k, AbstractValue value
@@ -972,14 +923,12 @@ private predicate unary_simple_comparison_eq(
     case.getValue().toInt() = k
   )
   or
-  isRelevantUnaryComparisonOperand(op) and
-  op.getDef() = test.getAnInstruction() and
-  (
-    k = 1 and
-    value.(BooleanValue).getValue() = true
+  exists(Instruction const | int_value(const) = k |
+    value.(BooleanValue).getValue() = true and
+    test.(CompareEQValueNumber).hasOperands(op, const.getAUse())
     or
-    k = 0 and
-    value.(BooleanValue).getValue() = false
+    value.(BooleanValue).getValue() = false and
+    test.(CompareNEValueNumber).hasOperands(op, const.getAUse())
   )
 }