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Merge pull request #14495 from github/calumgrant/comp-generated-this

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C++: Fix ImplicitThisFieldAccess
This commit is contained in:
Mathias Vorreiter Pedersen
2023-10-20 15:25:26 +01:00
committed by GitHub
parent f562d5319f 8054a5d086
commit 6c10ba2fb1
6 changed files with 40 additions and 37 deletions
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4
cpp/ql/lib/change-notes/2023-10-20-implicit-this.md Normal file
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@@ -0,0 +1,4 @@
---
category: minorAnalysis
---
* More field accesses are identified as `ImplicitThisFieldAccess`.

10
cpp/ql/lib/semmle/code/cpp/exprs/Access.qll
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@@ -306,15 +306,13 @@ private predicate exprHasReferenceConversion(Expr e) { referenceConversion(e.get
* }
* };
* ```
* Note: the C++ front-end often automatically desugars `field` to
* `this->field`, so most accesses of `this->field` are instances
* of `PointerFieldAccess` (with `ThisExpr` as the qualifier), not
* `ImplicitThisFieldAccess`.
*/
class ImplicitThisFieldAccess extends FieldAccess {
override string getAPrimaryQlClass() { result = "ImplicitThisFieldAccess" }
ImplicitThisFieldAccess() { not exists(this.getQualifier()) }
ImplicitThisFieldAccess() {
this.getQualifier().(ThisExpr).isCompilerGenerated() or not exists(this.getQualifier())
}
}
/**
@@ -332,7 +330,7 @@ class PointerToFieldLiteral extends ImplicitThisFieldAccess {
// access without a qualifier. The only other unqualified field accesses it
// emits are for compiler-generated constructors and destructors. When we
// filter those out, there are only pointer-to-field literals left.
not this.isCompilerGenerated()
not this.isCompilerGenerated() and not exists(this.getQualifier())
}
override predicate isConstant() { any() }

3
cpp/ql/lib/semmle/code/cpp/valuenumbering/HashCons.qll
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@@ -372,7 +372,8 @@ private predicate analyzablePointerFieldAccess(PointerFieldAccess access) {
private predicate mk_PointerFieldAccess(HashCons qualifier, Field target, PointerFieldAccess access) {
analyzablePointerFieldAccess(access) and
target = access.getTarget() and
qualifier = hashCons(access.getQualifier().getFullyConverted())
qualifier = hashCons(access.getQualifier().getFullyConverted()) and
not access instanceof ImplicitThisFieldAccess
}
private predicate analyzableImplicitThisFieldAccess(ImplicitThisFieldAccess access) {

4
cpp/ql/test/examples/expressions/PrintAST.expected
View File

@@ -1298,7 +1298,7 @@ union_etc.cpp:
# 6| getExpr(): [AssignExpr] ... = ...
# 6| Type = [IntType] int
# 6| ValueCategory = lvalue
# 6| getLValue(): [PointerFieldAccess] x
# 6| getLValue(): [ImplicitThisFieldAccess,PointerFieldAccess] x
# 6| Type = [IntType] int
# 6| ValueCategory = lvalue
# 6| getQualifier(): [ThisExpr] this
@@ -1488,7 +1488,7 @@ union_etc.cpp:
# 33| getExpr(): [AssignExpr] ... = ...
# 33| Type = [IntType] int
# 33| ValueCategory = lvalue
# 33| getLValue(): [PointerFieldAccess] q
# 33| getLValue(): [ImplicitThisFieldAccess,PointerFieldAccess] q
# 33| Type = [IntType] int
# 33| ValueCategory = lvalue
# 33| getQualifier(): [ThisExpr] this

10
cpp/ql/test/library-tests/access/FieldAccess/FieldAccess.expected
View File

@@ -1,6 +1,6 @@
| FieldAccess.cpp:11:12:11:13 | p1 | ptr |
| FieldAccess.cpp:12:12:12:13 | p2 | ptr |
| FieldAccess.cpp:25:12:25:13 | x1 | ptr |
| FieldAccess.cpp:11:12:11:13 | p1 | ptr, this |
| FieldAccess.cpp:12:12:12:13 | p2 | ptr, this |
| FieldAccess.cpp:25:12:25:13 | x1 | ptr, this |
| FieldAccess.cpp:29:18:29:19 | x2 | ptr |
| FieldAccess.cpp:34:3:34:3 | d | this |
| FieldAccess.cpp:45:13:45:14 | x1 | ptr |
@@ -19,10 +19,10 @@
| FieldAccess.cpp:91:7:91:7 | x | val |
| FieldAccess.cpp:91:13:91:13 | y | ref |
| FieldAccess.cpp:92:8:92:8 | x | ptr |
| FieldAccess.cpp:92:12:92:12 | y | ptr |
| FieldAccess.cpp:92:12:92:12 | y | ptr, this |
| FieldAccess.cpp:93:8:93:8 | x | ptr |
| FieldAccess.cpp:93:18:93:18 | y | ptr |
| FieldAccess.cpp:94:11:94:11 | y | ptr |
| FieldAccess.cpp:94:20:94:20 | y | val |
| FieldAccess.cpp:113:5:113:5 | x | ptr |
| FieldAccess.cpp:113:5:113:5 | x | ptr, this |
| FieldAccess.cpp:116:3:116:3 | v | this |

46
cpp/ql/test/library-tests/ir/ir/PrintAST.expected
View File

@@ -83,7 +83,7 @@ bad_asts.cpp:
# 10| Type = [IntType] int
# 10| Value = [Literal] 6
# 10| ValueCategory = prvalue
# 10| getRightOperand(): [PointerFieldAccess] x
# 10| getRightOperand(): [ImplicitThisFieldAccess,PointerFieldAccess] x
# 10| Type = [IntType] int
# 10| ValueCategory = prvalue(load)
# 10| getQualifier(): [ThisExpr] this
@@ -108,7 +108,7 @@ bad_asts.cpp:
# 10| Type = [IntType] int
# 10| Value = [Literal] t
# 10| ValueCategory = prvalue
# 10| getRightOperand(): [PointerFieldAccess] x
# 10| getRightOperand(): [ImplicitThisFieldAccess,PointerFieldAccess] x
# 10| Type = [IntType] int
# 10| ValueCategory = prvalue(load)
# 10| getQualifier(): [ThisExpr] this
@@ -5718,7 +5718,7 @@ ir.cpp:
# 645| getExpr(): [AssignExpr] ... = ...
# 645| Type = [IntType] int
# 645| ValueCategory = lvalue
# 645| getLValue(): [PointerFieldAccess] m_a
# 645| getLValue(): [ImplicitThisFieldAccess,PointerFieldAccess] m_a
# 645| Type = [IntType] int
# 645| ValueCategory = lvalue
# 645| getQualifier(): [ThisExpr] this
@@ -5770,7 +5770,7 @@ ir.cpp:
# 649| getLValue(): [VariableAccess] x
# 649| Type = [IntType] int
# 649| ValueCategory = lvalue
# 649| getRValue(): [PointerFieldAccess] m_a
# 649| getRValue(): [ImplicitThisFieldAccess,PointerFieldAccess] m_a
# 649| Type = [IntType] int
# 649| ValueCategory = prvalue(load)
# 649| getQualifier(): [ThisExpr] this
@@ -9018,7 +9018,7 @@ ir.cpp:
# 1043| getArrayBase(): [FunctionCall] call to c_str
# 1043| Type = [PointerType] const char *
# 1043| ValueCategory = prvalue
# 1043| getQualifier(): [PointerFieldAccess] s
# 1043| getQualifier(): [ImplicitThisFieldAccess,PointerFieldAccess] s
# 1043| Type = [LValueReferenceType] const String &
# 1043| ValueCategory = prvalue(load)
# 1043| getQualifier(): [ThisExpr] this
@@ -9027,7 +9027,7 @@ ir.cpp:
# 1043| getQualifier().getFullyConverted(): [ReferenceDereferenceExpr] (reference dereference)
# 1043| Type = [SpecifiedType] const String
# 1043| ValueCategory = lvalue
# 1043| getArrayOffset(): [PointerFieldAccess] x
# 1043| getArrayOffset(): [ImplicitThisFieldAccess,PointerFieldAccess] x
# 1043| Type = [LValueReferenceType] int &
# 1043| ValueCategory = prvalue(load)
# 1043| getQualifier(): [ThisExpr] this
@@ -9076,13 +9076,13 @@ ir.cpp:
# 1045| getArrayBase(): [FunctionCall] call to c_str
# 1045| Type = [PointerType] const char *
# 1045| ValueCategory = prvalue
# 1045| getQualifier(): [PointerFieldAccess] s
# 1045| getQualifier(): [ImplicitThisFieldAccess,PointerFieldAccess] s
# 1045| Type = [SpecifiedType] const String
# 1045| ValueCategory = lvalue
# 1045| getQualifier(): [ThisExpr] this
# 1045| Type = [PointerType] const lambda [] type at line 1045, col. 21 *
# 1045| ValueCategory = prvalue(load)
# 1045| getArrayOffset(): [PointerFieldAccess] x
# 1045| getArrayOffset(): [ImplicitThisFieldAccess,PointerFieldAccess] x
# 1045| Type = [IntType] int
# 1045| ValueCategory = prvalue(load)
# 1045| getQualifier(): [ThisExpr] this
@@ -9114,7 +9114,7 @@ ir.cpp:
# 1047| getArrayBase(): [FunctionCall] call to c_str
# 1047| Type = [PointerType] const char *
# 1047| ValueCategory = prvalue
# 1047| getQualifier(): [PointerFieldAccess] s
# 1047| getQualifier(): [ImplicitThisFieldAccess,PointerFieldAccess] s
# 1047| Type = [LValueReferenceType] const String &
# 1047| ValueCategory = prvalue(load)
# 1047| getQualifier(): [ThisExpr] this
@@ -9167,7 +9167,7 @@ ir.cpp:
# 1049| getArrayBase(): [FunctionCall] call to c_str
# 1049| Type = [PointerType] const char *
# 1049| ValueCategory = prvalue
# 1049| getQualifier(): [PointerFieldAccess] s
# 1049| getQualifier(): [ImplicitThisFieldAccess,PointerFieldAccess] s
# 1049| Type = [SpecifiedType] const String
# 1049| ValueCategory = lvalue
# 1049| getQualifier(): [ThisExpr] this
@@ -9203,7 +9203,7 @@ ir.cpp:
# 1051| getArrayBase(): [FunctionCall] call to c_str
# 1051| Type = [PointerType] const char *
# 1051| ValueCategory = prvalue
# 1051| getQualifier(): [PointerFieldAccess] s
# 1051| getQualifier(): [ImplicitThisFieldAccess,PointerFieldAccess] s
# 1051| Type = [LValueReferenceType] const String &
# 1051| ValueCategory = prvalue(load)
# 1051| getQualifier(): [ThisExpr] this
@@ -9212,7 +9212,7 @@ ir.cpp:
# 1051| getQualifier().getFullyConverted(): [ReferenceDereferenceExpr] (reference dereference)
# 1051| Type = [SpecifiedType] const String
# 1051| ValueCategory = lvalue
# 1051| getArrayOffset(): [PointerFieldAccess] x
# 1051| getArrayOffset(): [ImplicitThisFieldAccess,PointerFieldAccess] x
# 1051| Type = [IntType] int
# 1051| ValueCategory = prvalue(load)
# 1051| getQualifier(): [ThisExpr] this
@@ -9244,7 +9244,7 @@ ir.cpp:
# 1054| getArrayBase(): [FunctionCall] call to c_str
# 1054| Type = [PointerType] const char *
# 1054| ValueCategory = prvalue
# 1054| getQualifier(): [PointerFieldAccess] s
# 1054| getQualifier(): [ImplicitThisFieldAccess,PointerFieldAccess] s
# 1054| Type = [LValueReferenceType] const String &
# 1054| ValueCategory = prvalue(load)
# 1054| getQualifier(): [ThisExpr] this
@@ -9259,7 +9259,7 @@ ir.cpp:
# 1054| getLeftOperand(): [AddExpr] ... + ...
# 1054| Type = [IntType] int
# 1054| ValueCategory = prvalue
# 1054| getLeftOperand(): [PointerFieldAccess] x
# 1054| getLeftOperand(): [ImplicitThisFieldAccess,PointerFieldAccess] x
# 1054| Type = [IntType] int
# 1054| ValueCategory = prvalue(load)
# 1054| getQualifier(): [ThisExpr] this
@@ -11490,7 +11490,7 @@ ir.cpp:
# 1458| getExpr(): [AssignExpr] ... = ...
# 1458| Type = [IntType] int
# 1458| ValueCategory = lvalue
# 1458| getLValue(): [PointerFieldAccess] y
# 1458| getLValue(): [ImplicitThisFieldAccess,PointerFieldAccess] y
# 1458| Type = [IntType] int
# 1458| ValueCategory = lvalue
# 1458| getQualifier(): [ThisExpr] this
@@ -12302,7 +12302,7 @@ ir.cpp:
# 1567| <params>:
# 1567| getEntryPoint(): [BlockStmt] { ... }
# 1568| getStmt(0): [ReturnStmt] return ...
# 1568| getExpr(): [PointerFieldAccess] i
# 1568| getExpr(): [ImplicitThisFieldAccess,PointerFieldAccess] i
# 1568| Type = [IntType] int
# 1568| ValueCategory = lvalue
# 1568| getQualifier(): [ThisExpr] this
@@ -12315,7 +12315,7 @@ ir.cpp:
# 1571| <params>:
# 1571| getEntryPoint(): [BlockStmt] { ... }
# 1572| getStmt(0): [ReturnStmt] return ...
# 1572| getExpr(): [PointerFieldAccess] d
# 1572| getExpr(): [ImplicitThisFieldAccess,PointerFieldAccess] d
# 1572| Type = [DoubleType] double
# 1572| ValueCategory = lvalue
# 1572| getQualifier(): [ThisExpr] this
@@ -12328,7 +12328,7 @@ ir.cpp:
# 1575| <params>:
# 1575| getEntryPoint(): [BlockStmt] { ... }
# 1576| getStmt(0): [ReturnStmt] return ...
# 1576| getExpr(): [PointerFieldAccess] r
# 1576| getExpr(): [ImplicitThisFieldAccess,PointerFieldAccess] r
# 1576| Type = [LValueReferenceType] int &
# 1576| ValueCategory = prvalue(load)
# 1576| getQualifier(): [ThisExpr] this
@@ -12669,7 +12669,7 @@ ir.cpp:
# 1633| <params>:
# 1633| getEntryPoint(): [BlockStmt] { ... }
# 1634| getStmt(0): [ReturnStmt] return ...
# 1634| getExpr(): [PointerFieldAccess] i
# 1634| getExpr(): [ImplicitThisFieldAccess,PointerFieldAccess] i
# 1634| Type = [IntType] int
# 1634| ValueCategory = prvalue(load)
# 1634| getQualifier(): [ThisExpr] this
@@ -12679,7 +12679,7 @@ ir.cpp:
# 1637| <params>:
# 1637| getEntryPoint(): [BlockStmt] { ... }
# 1638| getStmt(0): [ReturnStmt] return ...
# 1638| getExpr(): [PointerFieldAccess] r
# 1638| getExpr(): [ImplicitThisFieldAccess,PointerFieldAccess] r
# 1638| Type = [LValueReferenceType] int &
# 1638| ValueCategory = prvalue(load)
# 1638| getQualifier(): [ThisExpr] this
@@ -13290,7 +13290,7 @@ ir.cpp:
# 1703| getQualifier(): [AddressOfExpr] & ...
# 1703| Type = [PointerType] const TrivialLambdaClass *
# 1703| ValueCategory = prvalue
# 1703| getOperand(): [PointerFieldAccess] (captured this)
# 1703| getOperand(): [ImplicitThisFieldAccess,PointerFieldAccess] (captured this)
# 1703| Type = [SpecifiedType] const TrivialLambdaClass
# 1703| ValueCategory = lvalue
# 1703| getQualifier(): [ThisExpr] this
@@ -13337,7 +13337,7 @@ ir.cpp:
# 1706| getQualifier(): [AddressOfExpr] & ...
# 1706| Type = [PointerType] const TrivialLambdaClass *
# 1706| ValueCategory = prvalue
# 1706| getOperand(): [PointerFieldAccess] (captured this)
# 1706| getOperand(): [ImplicitThisFieldAccess,PointerFieldAccess] (captured this)
# 1706| Type = [SpecifiedType] const TrivialLambdaClass
# 1706| ValueCategory = lvalue
# 1706| getQualifier(): [ThisExpr] this
@@ -13480,7 +13480,7 @@ ir.cpp:
# 1726| getExpr(): [AssignExpr] ... = ...
# 1726| Type = [IntType] int
# 1726| ValueCategory = lvalue
# 1726| getLValue(): [PointerFieldAccess] x
# 1726| getLValue(): [ImplicitThisFieldAccess,PointerFieldAccess] x
# 1726| Type = [IntType] int
# 1726| ValueCategory = lvalue
# 1726| getQualifier(): [ThisExpr] this