[ubsan] Add -fsanitize-undefined-strip-path-components=N
Summary:
This option allows the user to control how much of the file name is
emitted by UBSan. Tuning this option allows one to save space in the
resulting binary, which is helpful for restricted execution
environments.
With a positive N, UBSan skips the first N path components.
With a negative N, UBSan only keeps the last N path components.
Reviewers: rsmith
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D19666
llvm-svn: 269309
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 3ecd8e3..8896eb4 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -32,6 +32,7 @@
#include "llvm/IR/MDBuilder.h"
#include "llvm/Support/ConvertUTF.h"
#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/Path.h"
#include "llvm/Transforms/Utils/SanitizerStats.h"
using namespace clang;
@@ -2367,7 +2368,33 @@
PresumedLoc PLoc = getContext().getSourceManager().getPresumedLoc(Loc);
if (PLoc.isValid()) {
- auto FilenameGV = CGM.GetAddrOfConstantCString(PLoc.getFilename(), ".src");
+ StringRef FilenameString = PLoc.getFilename();
+
+ int PathComponentsToStrip =
+ CGM.getCodeGenOpts().EmitCheckPathComponentsToStrip;
+ if (PathComponentsToStrip < 0) {
+ assert(PathComponentsToStrip != INT_MIN);
+ int PathComponentsToKeep = -PathComponentsToStrip;
+ auto I = llvm::sys::path::rbegin(FilenameString);
+ auto E = llvm::sys::path::rend(FilenameString);
+ while (I != E && --PathComponentsToKeep)
+ ++I;
+
+ FilenameString = FilenameString.substr(I - E);
+ } else if (PathComponentsToStrip > 0) {
+ auto I = llvm::sys::path::begin(FilenameString);
+ auto E = llvm::sys::path::end(FilenameString);
+ while (I != E && PathComponentsToStrip--)
+ ++I;
+
+ if (I != E)
+ FilenameString =
+ FilenameString.substr(I - llvm::sys::path::begin(FilenameString));
+ else
+ FilenameString = llvm::sys::path::filename(FilenameString);
+ }
+
+ auto FilenameGV = CGM.GetAddrOfConstantCString(FilenameString, ".src");
CGM.getSanitizerMetadata()->disableSanitizerForGlobal(
cast<llvm::GlobalVariable>(FilenameGV.getPointer()));
Filename = FilenameGV.getPointer();