[PATCH] D19968: [scan-build] fix warnings emitted on LLVM Hexagon code base

[Krzysztof Parzyszek via llvm-commits]

kparzysz added inline comments.

================
Comment at: lib/Target/Hexagon/HexagonInstrInfo.cpp:1304
@@ -1303,3 +1303,3 @@
   // that operand has been constant extended.
-  bool OpCExtended[4];
+  bool OpCExtended[4] = {false};
   if (NumOperands > 4)
----------------
apelete wrote:
> kparzysz wrote:
> > The array OpCExtended is initialized in the loop below (line 1308).
> This one was added to suppress a warning in the following case:
> 
> 1305.	​  if (NumOperands > 4)
> 1306.	​    NumOperands = 4;
> 1307.	​
> 1308.	​  for (int i = 0; i < NumOperands; i++)
> 1309.	​    OpCExtended[i] = (isOperandExtended(&MI, i) && isConstExtended(&MI));
> 1310.	​​  switch(Opc) {
> ...
> 1361.	​  case Hexagon::S4_storeiri_io:
> 1362.      return (OpCExtended[1] || isUInt<6>(MI.getOperand(1).getImm())) &&
> 1363.               (OpCExtended[2] || isInt<6>(MI.getOperand(2).getImm()));
> ...
> 1375.   }
> 
> If branches at lines 1305 and 1308 evaluate to 'false', then the branch condition at line 1362 would evaluate to a garbage value because OpCExtended wasn't initialized.
> 
> If this is OK for you, then I would need your help to commit this for me as I do not have commit access.
> 
> Thanks.
NumOperands is the number of operands in the instruction.  S4_storeiri_io has 3, so NumOperands will be 3.  The loop at 1308-1309 will initialize OpCExtended for i=0..2, so both references will be valid.


Repository:
  rL LLVM

http://reviews.llvm.org/D19968