Print out a debug message when the reglist fails the sanity check for Thumb Ld/St Multiple.

llvm-svn: 129365

llvm/lib/Target/ARM/Disassembler/ARMDisassemblerCore.h

@@ -139,6 +139,31 @@ static inline void setSlice(unsigned &Bits, unsigned From, unsigned To,
   Bits |= (Val & Mask) << To;
 }
 
+// Return an integer result equal to the number of bits of x that are ones.
+static inline uint32_t
+BitCount (uint64_t x)
+{
+    // c accumulates the total bits set in x
+    uint32_t c;
+    for (c = 0; x; ++c)
+    {
+        x &= x - 1; // clear the least significant bit set
+    }
+    return c;
+}
+
+static inline bool
+BitIsSet (const uint64_t value, const uint64_t bit)
+{
+    return (value & (1ull << bit)) != 0;
+}
+
+static inline bool
+BitIsClear (const uint64_t value, const uint64_t bit)
+{
+    return (value & (1ull << bit)) == 0;
+}
+
 /// Various utilities for checking the target specific flags.
 
 /// A unary data processing instruction doesn't have an Rn operand.

llvm/lib/Target/ARM/Disassembler/ThumbDisassemblerCore.h

@@ -901,6 +901,10 @@ static bool DisassembleThumb1LdStMul(bool Ld, MCInst &MI, unsigned Opcode,
   }
 
   unsigned RegListBits = slice(insn, 7, 0);
+  if (BitCount(RegListBits) < 1) {
+    DEBUG(errs() << "if BitCount(registers) < 1 then UNPREDICTABLE\n");
+    return false;
+  }
 
   // Fill the variadic part of reglist.
   for (unsigned i = 0; i < 8; ++i)

llvm/test/MC/Disassembler/ARM/invalid-STMIA_UPD-thumb.txt

@@ -0,0 +1,10 @@
+# RUN: llvm-mc --disassemble %s -triple=thumb-apple-darwin9 |& grep {invalid instruction encoding}
+
+# Opcode=2313 Name=tSTMIA_UPD 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 
+# -------------------------------------------------------------------------------------------------
+# | 0: 0: 0: 0| 0: 0: 0: 0| 0: 0: 0: 0| 0: 0: 0: 0| 1: 1: 0: 0| 0: 1: 1: 1| 0: 0: 0: 0| 0: 0: 0: 0|
+# -------------------------------------------------------------------------------------------------
+# 
+# if BitCount(registers) < 1 then UNPREDICTABLE
+0x00 0xc7