Add sanity checkings for Thumb2 Load/Store Register Exclusive family of operations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129531 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/ARM/Disassembler/ThumbDisassemblerCore.h

@@ -1232,29 +1232,66 @@ static bool DisassembleThumb2LdStEx(MCInst &MI, unsigned Opcode, uint32_t insn,
   bool isSW = (Opcode == ARM::t2LDREX || Opcode == ARM::t2STREX);
   bool isDW = (Opcode == ARM::t2LDREXD || Opcode == ARM::t2STREXD);
 
+  unsigned Rt  = decodeRd(insn);
+  unsigned Rt2 = decodeRs(insn); // But note that this is Rd for t2STREX.
+  unsigned Rd  = decodeRm(insn);
+  unsigned Rn  = decodeRn(insn);
+
+  // Some sanity checking first.
+  if (isStore) {
+    // if d == n || d == t then UNPREDICTABLE
+    // if d == n || d == t || d == t2 then UNPREDICTABLE
+    if (isDW) {
+      if (Rd == Rn || Rd == Rt || Rd == Rt2) {
+        DEBUG(errs() << "if d == n || d == t || d == t2 then UNPREDICTABLE\n");
+        return false;
+      }
+    } else {
+      if (isSW) {
+        if (Rt2 == Rn || Rt2 == Rt) {
+          DEBUG(errs() << "if d == n || d == t then UNPREDICTABLE\n");
+          return false;
+        }
+      } else {
+        if (Rd == Rn || Rd == Rt) {
+          DEBUG(errs() << "if d == n || d == t then UNPREDICTABLE\n");
+          return false;
+        }
+      }
+    }
+  } else {
+    // Load
+    // A8.6.71 LDREXD
+    // if t == t2 then UNPREDICTABLE
+    if (isDW && Rt == Rt2) {
+      DEBUG(errs() << "if t == t2 then UNPREDICTABLE\n");
+      return false;
+    }
+  }
+
   // Add the destination operand for store.
   if (isStore) {
     MI.addOperand(MCOperand::CreateReg(
                     getRegisterEnum(B, OpInfo[OpIdx].RegClass,
-                                    isSW ? decodeRs(insn) : decodeRm(insn))));
+                                    isSW ? Rt2 : Rd)));
     ++OpIdx;
   }
 
   // Source operand for store and destination operand for load.
   MI.addOperand(MCOperand::CreateReg(getRegisterEnum(B, OpInfo[OpIdx].RegClass,
-                                                     decodeRd(insn))));
+                                                     Rt)));
   ++OpIdx;
 
   // Thumb2 doubleword complication: with an extra source/destination operand.
   if (isDW) {
     MI.addOperand(MCOperand::CreateReg(getRegisterEnum(B,OpInfo[OpIdx].RegClass,
-                                                       decodeRs(insn))));
+                                                       Rt2)));
     ++OpIdx;
   }
 
   // Finally add the pointer operand.
   MI.addOperand(MCOperand::CreateReg(getRegisterEnum(B, OpInfo[OpIdx].RegClass,
-                                                     decodeRn(insn))));
+                                                     Rn)));
   ++OpIdx;
 
   return true;

test/MC/Disassembler/ARM/invalid-t2LDREXD-thumb.txt

@@ -0,0 +1,10 @@
+# RUN: llvm-mc --disassemble %s -triple=thumb-apple-darwin9 |& grep {invalid instruction encoding}
+
+# Opcode=1934 Name=t2LDREXD Format=ARM_FORMAT_THUMBFRM(25)
+#  31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0 
+# -------------------------------------------------------------------------------------------------
+# | 1: 1: 1: 0| 1: 0: 0: 0| 1: 1: 0: 1| 0: 0: 1: 0| 1: 0: 0: 0| 1: 0: 0: 0| 0: 1: 1: 1| 1: 1: 1: 1|
+# -------------------------------------------------------------------------------------------------
+# 
+# if t == t2 then UNPREDICTABLE
+0xd2 0xe8 0x7f 0x88

test/MC/Disassembler/ARM/invalid-t2STREXB-thumb.txt

@@ -0,0 +1,10 @@
+# RUN: llvm-mc --disassemble %s -triple=thumb-apple-darwin9 |& grep {invalid instruction encoding}
+
+# Opcode=2127 Name=t2STREXB Format=ARM_FORMAT_THUMBFRM(25)
+#  31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0 
+# -------------------------------------------------------------------------------------------------
+# | 1: 1: 1: 0| 1: 0: 0: 0| 1: 1: 0: 0| 0: 0: 1: 0| 1: 0: 0: 0| 1: 1: 1: 1| 0: 1: 0: 0| 0: 0: 1: 0|
+# -------------------------------------------------------------------------------------------------
+# 
+# if d == n || d == t then UNPREDICTABLE
+0xc2 0xe8 0x42 0x8f

test/MC/Disassembler/ARM/invalid-t2STREXD-thumb.txt

@@ -0,0 +1,10 @@
+# RUN: llvm-mc --disassemble %s -triple=thumb-apple-darwin9 |& grep {invalid instruction encoding}
+
+# Opcode=2128 Name=t2STREXD Format=ARM_FORMAT_THUMBFRM(25)
+#  31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10  9  8  7  6  5  4  3  2  1  0 
+# -------------------------------------------------------------------------------------------------
+# | 1: 1: 1: 0| 1: 0: 0: 0| 1: 1: 0: 0| 0: 0: 1: 0| 0: 1: 1: 1| 1: 0: 0: 0| 0: 1: 1: 1| 1: 0: 0: 0|
+# -------------------------------------------------------------------------------------------------
+# 
+# if d == n || d == t || d == t2 then UNPREDICTABLE
+mc-input.txt:1:1: warning: invalid instruction encoding

test/MC/Disassembler/ARM/thumb-tests.txt

@@ -158,6 +158,9 @@
 # CHECK:	ldrex	r8, [r2]
 0x52 0xe8 0x00 0x8f
 
+# CHECK:	ldrexd	r8, r9, [r2]
+0xd2 0xe8 0x7f 0x89
+
 # CHECK:	strexd	r1, r7, r8, [r2]
 0xc2 0xe8 0x71 0x78