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Work around Stmt::getID assertion failure on long string literals. (#552)
Fixes #544.
1 parent e0fb426 commit 8c66180

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4 files changed

+140
-1
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4 files changed

+140
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‎clang/include/clang/3C/Utils.h

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@@ -223,4 +223,9 @@ void getPrintfStringArgIndices(const clang::CallExpr *CE,
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const clang::ASTContext &Context,
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std::set<unsigned> &StringArgIndices);
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// Use instead of Stmt::getID since Stmt::getID fails an assertion on long
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// string literals (https://bugs.llvm.org/show_bug.cgi?id=49926).
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int64_t getStmtIdWorkaround(const clang::Stmt *St,
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const clang::ASTContext &Context);
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#endif

‎clang/lib/3C/ProgramInfo.cpp

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@@ -812,7 +812,7 @@ ProgramInfo::getExprKey(Expr *E, ASTContext *C) const {
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// is compiled multiple times with different defines
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std::string Name = C->getSourceManager().getFileEntryForID(
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C->getSourceManager().getMainFileID())->getName().str();
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return std::make_pair(E->getID(*C), Name);
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return std::make_pair(getStmtIdWorkaround(E, *C), Name);
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}
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bool ProgramInfo::hasPersistentConstraints(Expr *E, ASTContext *C) const {

‎clang/lib/3C/Utils.cpp

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@@ -563,3 +563,29 @@ void getPrintfStringArgIndices(const CallExpr *CE, const FunctionDecl *Callee,
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Context.getTargetInfo(), false);
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}
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}
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int64_t getStmtIdWorkaround(const Stmt *St, const ASTContext &Context) {
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// Stmt::getID uses Context.getAllocator().identifyKnownAlignedObject(St) to
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// derive a unique ID for St from its pointer in a way that should be
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// reproducible if the exact same source file is loaded in the exact same
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// environment, since if AST building is deterministic, the sequence of memory
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// allocations should be identical.
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// Context.getAllocator().identifyKnownObject(St) generates an ID that is
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// normally the offset of the Stmt object within the allocator's memory slabs,
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// so it is divisible by alignof(Stmt). identifyKnownAlignedObject wraps
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// identifyKnownObject to divide the ID by alignof(Stmt) (after asserting that
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// it is divisible), probably in an effort to produce smaller IDs to make some
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// data structures more efficient. However, if the Stmt is allocated in a
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// custom-size slab because it exceeds the default slab size of 4096, then
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// identifyKnownObject returns -1 minus the offset, which is _not_ divisible
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// by alignof(Stmt) because of the -1. Unfortunately,
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// identifyKnownAlignedObject doesn't account for this rare case, and its
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// assertion fails (https://bugs.llvm.org/show_bug.cgi?id=49926).
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//
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// Since 3C doesn't currently use the ID in a data structure that benefits
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// from smaller IDs, we may as well just use identifyKnownObject. If we wanted
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// smaller IDs, the solution would probably be to have
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// identifyKnownAlignedObject fix the alignment of negative IDs by subtracting
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// (alignof(Stmt) - 1) before dividing.
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return Context.getAllocator().identifyKnownObject(St);
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}

‎clang/test/3C/long_string_literal.c

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@@ -0,0 +1,108 @@
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// Test that 3C doesn't crash on long string literals
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// (https://github.com/correctcomputation/checkedc-clang/issues/544).
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// We only care that this doesn't crash.
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// RUN: 3c -base-dir=%S %s --
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// 100 lines * 50 characters, to make sure we exceed the default slab size of
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// 4096.
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char x[] = "01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789"
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"01234567890123456789012345678901234567890123456789";

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