Add sanity check for Ld/St Dual forms of Thumb2 instructions.

rdar://problem/9273947

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129411 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/Disassembler/ThumbDisassemblerCore.h b/lib/Target/ARM/Disassembler/ThumbDisassemblerCore.h
index e29d84604ecde544e2c303914ac6547efb84fa8c..42d7a73bf5f819cf42f76c1476ead81da69c36d4 100644 (file)
--- a/lib/Target/ARM/Disassembler/ThumbDisassemblerCore.h
+++ b/lib/Target/ARM/Disassembler/ThumbDisassemblerCore.h
@@ -1275,6 +1275,35 @@ static bool DisassembleThumb2LdStDual(MCInst &MI, unsigned Opcode,
          && OpInfo[3].RegClass < 0
          && "Expect >= 4 operands and first 3 as reg operands");
 
+  // Thumnb allows for specifying Rt and Rt2, unlike ARM (which has Rt2==Rt+1).
+  unsigned Rt  = decodeRd(insn);
+  unsigned Rt2 = decodeRs(insn);
+  unsigned Rn  = decodeRn(insn);
+
+  // Some sanity checking first.
+
+  // A8.6.67 LDRD (literal) has its W bit as (0).
+  if (Opcode == ARM::t2LDRDi8 || Opcode == ARM::t2LDRD_PRE || Opcode == ARM::t2LDRD_POST) {
+    if (Rn == 15 && slice(insn, 21, 21) != 0)
+      return false;
+  } else {
+    // For Dual Store, PC cannot be used as the base register.
+    if (Rn == 15) {
+      DEBUG(errs() << "if n == 15 then UNPREDICTABLE\n");
+      return false;
+    }
+  }
+  if (Rt == Rt2) {
+    DEBUG(errs() << "if t == t2 then UNPREDICTABLE\n");
+    return false;
+  }
+  if (Opcode != ARM::t2LDRDi8 && Opcode != ARM::t2STRDi8) {
+    if (Rn == Rt || Rn == Rt2) {
+      DEBUG(errs() << "if wback && (n == t || n == t2) then UNPREDICTABLE\n");
+      return false;
+    }
+  }
+
   // Add the <Rt> <Rt2> operands.
   unsigned RegClassPair = OpInfo[0].RegClass;
   unsigned RegClassBase = OpInfo[2].RegClass;

diff --git a/test/MC/Disassembler/ARM/invalid-LDRD_PRE-thumb.txt b/test/MC/Disassembler/ARM/invalid-LDRD_PRE-thumb.txt
new file mode 100644 (file)
index 0000000..da2e6be
--- /dev/null
+++ b/test/MC/Disassembler/ARM/invalid-LDRD_PRE-thumb.txt
@@ -0,0 +1,13 @@
+# RUN: llvm-mc --disassemble %s -triple=thumb-apple-darwin9 |& grep {invalid instruction encoding}
+
+# Opcode=1930 Name=t2LDRD_PRE 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: 1| 1: 1: 1: 1| 1: 1: 1: 1| 1: 1: 1: 0| 1: 0: 1: 1| 0: 0: 0: 0| 0: 0: 0: 0|
+# -------------------------------------------------------------------------------------------------
+# 
+# A8.6.66 LDRD (immediate)
+# if Rn = '1111' then SEE LDRD (literal)
+# A8.6.67 LDRD (literal)
+# Inst{21} = 0
+0xff 0xe9 0x0 0xeb

diff --git a/test/MC/Disassembler/ARM/invalid-t2STRD_PRE-thumb.txt b/test/MC/Disassembler/ARM/invalid-t2STRD_PRE-thumb.txt
new file mode 100644 (file)
index 0000000..c8f8ec2
--- /dev/null
+++ b/test/MC/Disassembler/ARM/invalid-t2STRD_PRE-thumb.txt
@@ -0,0 +1,10 @@
+# RUN: llvm-mc --disassemble %s -triple=thumb-apple-darwin9 |& grep {invalid instruction encoding}
+
+# Opcode=2124 Name=t2STRD_PRE 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: 1| 1: 1: 1: 0| 0: 1: 0: 0| 0: 1: 0: 0| 0: 1: 1: 0| 0: 0: 0: 0| 0: 0: 1: 0|
+# -------------------------------------------------------------------------------------------------
+# 
+# if wback && (n == t || n == t2) then UNPREDICTABLE
+0xe4 0xe9 0x02 0x46