[llvm] 13be274 - [AVR] Fix read of uninitialized variable AVRSubtarget:::ELFArch

[Dylan McKay via llvm-commits]

Author: Dylan McKay
Date: 2020-03-13T00:09:13+13:00
New Revision: 13be27482e5300ac8d7cafacd8a046a6611ad1c4

URL: https://github.com/llvm/llvm-project/commit/13be27482e5300ac8d7cafacd8a046a6611ad1c4
DIFF: https://github.com/llvm/llvm-project/commit/13be27482e5300ac8d7cafacd8a046a6611ad1c4.diff

LOG: [AVR] Fix read of uninitialized variable AVRSubtarget:::ELFArch

Found by the LLVM MemorySanitizer tests when switching AVR to a default
backend.

ELFArch must be initialized before the call to
initializeSubtargetDependencies().

The uninitialized read would occur deep within TableGen'd code.

Added: 
    

Modified: 
    llvm/lib/Target/AVR/AVRSubtarget.cpp
    llvm/lib/Target/AVR/AVRSubtarget.h

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AVR/AVRSubtarget.cpp b/llvm/lib/Target/AVR/AVRSubtarget.cpp
index 6a41036fdd6c..be5c4c06225b 100644
--- a/llvm/lib/Target/AVR/AVRSubtarget.cpp
+++ b/llvm/lib/Target/AVR/AVRSubtarget.cpp
@@ -29,7 +29,7 @@ namespace llvm {
 
 AVRSubtarget::AVRSubtarget(const Triple &TT, const std::string &CPU,
                            const std::string &FS, const AVRTargetMachine &TM)
-    : AVRGenSubtargetInfo(TT, CPU, FS), InstrInfo(), FrameLowering(),
+    : AVRGenSubtargetInfo(TT, CPU, FS), ELFArch(0), InstrInfo(), FrameLowering(),
       TLInfo(TM, initializeSubtargetDependencies(CPU, FS, TM)), TSInfo(),
 
       // Subtarget features
@@ -38,7 +38,7 @@ AVRSubtarget::AVRSubtarget(const Triple &TT, const std::string &CPU,
       m_hasMOVW(false), m_hasLPM(false), m_hasLPMX(false),  m_hasELPM(false),
       m_hasELPMX(false), m_hasSPM(false), m_hasSPMX(false), m_hasDES(false),
       m_supportsRMW(false), m_supportsMultiplication(false), m_hasBREAK(false),
-      m_hasTinyEncoding(false), ELFArch(false), m_FeatureSetDummy(false) {
+      m_hasTinyEncoding(false), m_FeatureSetDummy(false) {
   // Parse features string.
   ParseSubtargetFeatures(CPU, FS);
 }

diff  --git a/llvm/lib/Target/AVR/AVRSubtarget.h b/llvm/lib/Target/AVR/AVRSubtarget.h
index da9289af7c8d..aa813a15dc0a 100644
--- a/llvm/lib/Target/AVR/AVRSubtarget.h
+++ b/llvm/lib/Target/AVR/AVRSubtarget.h
@@ -81,6 +81,10 @@ class AVRSubtarget : public AVRGenSubtargetInfo {
   }
 
 private:
+
+  /// The ELF e_flags architecture.
+  unsigned ELFArch;
+
   AVRInstrInfo InstrInfo;
   AVRFrameLowering FrameLowering;
   AVRTargetLowering TLInfo;
@@ -107,9 +111,6 @@ class AVRSubtarget : public AVRGenSubtargetInfo {
   bool m_hasBREAK;
   bool m_hasTinyEncoding;
 
-  /// The ELF e_flags architecture.
-  unsigned ELFArch;
-
   // Dummy member, used by FeatureSet's. We cannot have a SubtargetFeature with
   // no variable, so we instead bind pseudo features to this variable.
   bool m_FeatureSetDummy;