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[Preamble] Fix an undefined behavior when checking an empty preamble can be reused.
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Authored by hokein on Aug 20 2018, 5:28 AM.

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Summary

Passing nullptr to memcmp is UB.

Repository

rC Clang

Build Status

Buildable 21671
Build 21671: arc lint + arc unit

Use the std::equal to replace the memcmp.

LGTM. Thanks!

This revision is now accepted and ready to land.Aug 22 2018, 2:29 AM

This revision was automatically updated to reflect the committed changes.

Path

Size

lib/

Frontend/

3 lines

Show First 20 Lines • Show All 410 Lines • ▼ Show 20 Lines	bool PrecompiledPreamble::CanReuse(const CompilerInvocation &Invocation,
const llvm::MemoryBuffer *MainFileBuffer,		const llvm::MemoryBuffer *MainFileBuffer,
PreambleBounds Bounds,		PreambleBounds Bounds,
vfs::FileSystem *VFS) const {		vfs::FileSystem *VFS) const {

assert(		assert(
Bounds.Size <= MainFileBuffer->getBufferSize() &&		Bounds.Size <= MainFileBuffer->getBufferSize() &&
"Buffer is too large. Bounds were calculated from a different buffer?");		"Buffer is too large. Bounds were calculated from a different buffer?");

		if (Bounds.Size == 0)
		return PreambleBytes.size() == Bounds.Size;

auto PreambleInvocation = std::make_shared<CompilerInvocation>(Invocation);		auto PreambleInvocation = std::make_shared<CompilerInvocation>(Invocation);
PreprocessorOptions &PreprocessorOpts =		PreprocessorOptions &PreprocessorOpts =
PreambleInvocation->getPreprocessorOpts();		PreambleInvocation->getPreprocessorOpts();

// We've previously computed a preamble. Check whether we have the same		// We've previously computed a preamble. Check whether we have the same
// preamble now that we did before, and that there's enough space in		// preamble now that we did before, and that there's enough space in
// the main-file buffer within the precompiled preamble to fit the		// the main-file buffer within the precompiled preamble to fit the
// new main file.		// new main file.
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