[PATCH] D104097: [analyzer] Fix calculating offset for fields with an empty type
Georgy Komarov via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Sat Jul 3 20:58:05 PDT 2021
This revision was automatically updated to reflect the committed changes.
Closed by commit rGc558b1fca735: [analyzer] Fix calculating offset for fields with an empty type (authored by jubnzv).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D104097/new/
https://reviews.llvm.org/D104097
Files:
clang/lib/StaticAnalyzer/Checkers/PaddingChecker.cpp
clang/test/Analysis/padding_no_unique_address.cpp
Index: clang/test/Analysis/padding_no_unique_address.cpp
===================================================================
--- /dev/null
+++ clang/test/Analysis/padding_no_unique_address.cpp
@@ -0,0 +1,30 @@
+// RUN: %clang_analyze_cc1 -std=c++14 -triple x86_64-linux-gnu -analyzer-checker=optin.performance -analyzer-config optin.performance.Padding:AllowedPad=2 -verify %s
+
+class Empty {}; // no-warning
+
+// expected-warning at +1{{Excessive padding in 'struct NoUniqueAddressWarn1' (6 padding}}
+struct NoUniqueAddressWarn1 {
+ char c1;
+ [[no_unique_address]] Empty empty;
+ int i;
+ char c2;
+};
+
+// expected-warning at +1{{Excessive padding in 'struct NoUniqueAddressWarn2' (6 padding}}
+struct NoUniqueAddressWarn2 {
+ char c1;
+ [[no_unique_address]] Empty e1, e2;
+ int i;
+ char c2;
+};
+
+struct NoUniqueAddressNoWarn1 {
+ char c1;
+ [[no_unique_address]] Empty empty;
+ char c2;
+};
+
+struct NoUniqueAddressNoWarn2 {
+ char c1;
+ [[no_unique_address]] Empty e1, e2;
+};
Index: clang/lib/StaticAnalyzer/Checkers/PaddingChecker.cpp
===================================================================
--- clang/lib/StaticAnalyzer/Checkers/PaddingChecker.cpp
+++ clang/lib/StaticAnalyzer/Checkers/PaddingChecker.cpp
@@ -193,6 +193,11 @@
CharUnits PaddingSum;
CharUnits Offset = ASTContext.toCharUnitsFromBits(RL.getFieldOffset(0));
for (const FieldDecl *FD : RD->fields()) {
+ // Skip field that is a subobject of zero size, marked with
+ // [[no_unique_address]] or an empty bitfield, because its address can be
+ // set the same as the other fields addresses.
+ if (FD->isZeroSize(ASTContext))
+ continue;
// This checker only cares about the padded size of the
// field, and not the data size. If the field is a record
// with tail padding, then we won't put that number in our
@@ -249,7 +254,7 @@
RetVal.Field = FD;
auto &Ctx = FD->getASTContext();
auto Info = Ctx.getTypeInfoInChars(FD->getType());
- RetVal.Size = Info.Width;
+ RetVal.Size = FD->isZeroSize(Ctx) ? CharUnits::Zero() : Info.Width;
RetVal.Align = Info.Align;
assert(llvm::isPowerOf2_64(RetVal.Align.getQuantity()));
if (auto Max = FD->getMaxAlignment())
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