[llvm] r364635 - [ARM] Fix integer UB in MVE load/store immediate handling.

[Simon Tatham via llvm-commits]

Author: statham
Date: Fri Jun 28 02:28:39 2019
New Revision: 364635

URL: http://llvm.org/viewvc/llvm-project?rev=364635&view=rev
Log:
[ARM] Fix integer UB in MVE load/store immediate handling.

Modified:
    llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
    llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp

Modified: llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp?rev=364635&r1=364634&r2=364635&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp (original)
+++ llvm/trunk/lib/Target/ARM/Disassembler/ARMDisassembler.cpp Fri Jun 28 02:28:39 2019
@@ -4182,7 +4182,7 @@ static DecodeStatus DecodeT2Imm7(MCInst
   else if (!(Val & 0x80))
     imm *= -1;
   if (imm != INT32_MIN)
-    imm <<= shift;
+    imm *= (1U << shift);
   Inst.addOperand(MCOperand::createImm(imm));
 
   return MCDisassembler::Success;
@@ -4448,7 +4448,7 @@ static DecodeStatus DecodeMveAddrModeQ(M
       imm *= -1;
   }
   if (imm != INT32_MIN)
-    imm <<= shift;
+    imm *= (1U << shift);
   Inst.addOperand(MCOperand::createImm(imm));
 
   return S;

Modified: llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp?rev=364635&r1=364634&r2=364635&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp (original)
+++ llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp Fri Jun 28 02:28:39 2019
@@ -1621,12 +1621,15 @@ getT2AddrModeImmOpValue(const MCInst &MI
   // If the immediate is B bits long, we need B+1 bits in order
   // to represent the (inverse of the) sign bit.
   Value <<= (Bits + 1);
-  int32_t tmp = (int32_t)MO2.getImm() >> Shift;
-  if (tmp < 0)
+  int32_t tmp = (int32_t)MO2.getImm();
+  if (tmp == INT32_MIN) { // represents subtracting zero rather than adding it
+    tmp = 0;
+  } else if (tmp < 0) {
     tmp = abs(tmp);
-  else
+  } else {
     Value |= (1U << Bits); // Set the ADD bit
-  Value |= tmp & ((1U << Bits) - 1);
+  }
+  Value |= (tmp >> Shift) & ((1U << Bits) - 1);
   return Value;
 }