[llvm] r366398 - [RISCV] Avoid signed integer overflow UB in RISCVMatInt::generateInstSeq

[Alex Bradbury via llvm-commits]

Author: asb
Date: Wed Jul 17 21:02:58 2019
New Revision: 366398

URL: http://llvm.org/viewvc/llvm-project?rev=366398&view=rev
Log:
[RISCV] Avoid signed integer overflow UB in RISCVMatInt::generateInstSeq

Found by UBSan.

Modified:
    llvm/trunk/lib/Target/RISCV/Utils/RISCVMatInt.cpp

Modified: llvm/trunk/lib/Target/RISCV/Utils/RISCVMatInt.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/RISCV/Utils/RISCVMatInt.cpp?rev=366398&r1=366397&r2=366398&view=diff
==============================================================================
--- llvm/trunk/lib/Target/RISCV/Utils/RISCVMatInt.cpp (original)
+++ llvm/trunk/lib/Target/RISCV/Utils/RISCVMatInt.cpp Wed Jul 17 21:02:58 2019
@@ -64,7 +64,7 @@ void generateInstSeq(int64_t Val, bool I
   // performed when the recursion returns.
 
   int64_t Lo12 = SignExtend64<12>(Val);
-  int64_t Hi52 = (Val + 0x800) >> 12;
+  int64_t Hi52 = ((uint64_t)Val + 0x800ull) >> 12;
   int ShiftAmount = 12 + findFirstSet((uint64_t)Hi52);
   Hi52 = SignExtend64(Hi52 >> (ShiftAmount - 12), 64 - ShiftAmount);