From eae1d34029c159306ce4a0472294de6cf9baedac Mon Sep 17 00:00:00 2001
From: Tim Northover <Tim.Northover@arm.com>
Date: Thu, 6 Sep 2012 15:17:49 +0000
Subject: Check for invalid alignment values when decoding VLDn/VSTn (single
 ln) instructions.

Patch by Chris Lidbury.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163321 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/Disassembler/ARMDisassembler.cpp | 46 ++++++++++++++++++++-----
 1 file changed, 38 insertions(+), 8 deletions(-)

(limited to 'lib/Target/ARM')

diff --git a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index c394ed1579..657c103462 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -3710,8 +3710,16 @@ static DecodeStatus DecodeVLD1LN(MCInst &Inst, unsigned Insn,
       if (fieldFromInstruction(Insn, 6, 1))
         return MCDisassembler::Fail; // UNDEFINED
       index = fieldFromInstruction(Insn, 7, 1);
-      if (fieldFromInstruction(Insn, 4, 2) != 0)
-        align = 4;
+
+      switch (fieldFromInstruction(Insn, 4, 2)) {
+        case 0 :
+          align = 0; break;
+        case 3:
+          align = 4; break;
+        default:
+          return MCDisassembler::Fail;
+      }
+      break;
   }
 
   if (!Check(S, DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)))
@@ -3769,8 +3777,16 @@ static DecodeStatus DecodeVST1LN(MCInst &Inst, unsigned Insn,
       if (fieldFromInstruction(Insn, 6, 1))
         return MCDisassembler::Fail; // UNDEFINED
       index = fieldFromInstruction(Insn, 7, 1);
-      if (fieldFromInstruction(Insn, 4, 2) != 0)
-        align = 4;
+
+      switch (fieldFromInstruction(Insn, 4, 2)) {
+        case 0: 
+          align = 0; break;
+        case 3:
+          align = 4; break;
+        default:
+          return MCDisassembler::Fail;
+      }
+      break;
   }
 
   if (Rm != 0xF) { // Writeback
@@ -4090,8 +4106,15 @@ static DecodeStatus DecodeVLD4LN(MCInst &Inst, unsigned Insn,
         inc = 2;
       break;
     case 2:
-      if (fieldFromInstruction(Insn, 4, 2))
-        align = 4 << fieldFromInstruction(Insn, 4, 2);
+      switch (fieldFromInstruction(Insn, 4, 2)) {
+        case 0:
+          align = 0; break;
+        case 3:
+          return MCDisassembler::Fail;
+        default:
+          align = 4 << fieldFromInstruction(Insn, 4, 2); break;
+      }
+
       index = fieldFromInstruction(Insn, 7, 1);
       if (fieldFromInstruction(Insn, 6, 1))
         inc = 2;
@@ -4164,8 +4187,15 @@ static DecodeStatus DecodeVST4LN(MCInst &Inst, unsigned Insn,
         inc = 2;
       break;
     case 2:
-      if (fieldFromInstruction(Insn, 4, 2))
-        align = 4 << fieldFromInstruction(Insn, 4, 2);
+      switch (fieldFromInstruction(Insn, 4, 2)) {
+        case 0:
+          align = 0; break;
+        case 3:
+          return MCDisassembler::Fail;
+        default:
+          align = 4 << fieldFromInstruction(Insn, 4, 2); break;
+      }
+
       index = fieldFromInstruction(Insn, 7, 1);
       if (fieldFromInstruction(Insn, 6, 1))
         inc = 2;
-- 
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