[llvm] r333728 - [X86][Disassembler] Make it an error to set EVEX.R' to 0 when modrm.reg encodes a GPR.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Thu May 31 23:11:29 2018
New Revision: 333728

URL: http://llvm.org/viewvc/llvm-project?rev=333728&view=rev
Log:
[X86][Disassembler] Make it an error to set EVEX.R' to 0 when modrm.reg encodes a GPR.

This is different than the behavior of EVEX.X extending modrm.rm to 5 bits.

Added:
    llvm/trunk/test/MC/Disassembler/X86/invalid-EVEX-R2.txt
Modified:
    llvm/trunk/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp

Modified: llvm/trunk/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp?rev=333728&r1=333727&r2=333728&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp (original)
+++ llvm/trunk/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp Thu May 31 23:11:29 2018
@@ -1445,7 +1445,7 @@ static int readModRM(struct InternalInst
   return 0;
 }
 
-#define GENERIC_FIXUP_FUNC(name, base, prefix)            \
+#define GENERIC_FIXUP_FUNC(name, base, prefix, mask)      \
   static uint16_t name(struct InternalInstruction *insn,  \
                        OperandType type,                  \
                        uint8_t index,                     \
@@ -1459,7 +1459,9 @@ static int readModRM(struct InternalInst
     case TYPE_Rv:                                         \
       return base + index;                                \
     case TYPE_R8:                                         \
-      index &= 0xf;                                       \
+      index &= mask;                                      \
+      if (index > 0xf)                                    \
+        *valid = 0;                                       \
       if (insn->rexPrefix &&                              \
          index >= 4 && index <= 7) {                      \
         return prefix##_SPL + (index - 4);                \
@@ -1467,11 +1469,20 @@ static int readModRM(struct InternalInst
         return prefix##_AL + index;                       \
       }                                                   \
     case TYPE_R16:                                        \
-      return prefix##_AX + (index & 0xf);                 \
+      index &= mask;                                      \
+      if (index > 0xf)                                    \
+        *valid = 0;                                       \
+      return prefix##_AX + index;                         \
     case TYPE_R32:                                        \
-      return prefix##_EAX + (index & 0xf);                \
+      index &= mask;                                      \
+      if (index > 0xf)                                    \
+        *valid = 0;                                       \
+      return prefix##_EAX + index;                        \
     case TYPE_R64:                                        \
-      return prefix##_RAX + (index & 0xf);                \
+      index &= mask;                                      \
+      if (index > 0xf)                                    \
+        *valid = 0;                                       \
+      return prefix##_RAX + index;                        \
     case TYPE_ZMM:                                        \
       return prefix##_ZMM0 + index;                       \
     case TYPE_YMM:                                        \
@@ -1519,8 +1530,8 @@ static int readModRM(struct InternalInst
  *                field is valid for the register class; 0 if not.
  * @return      - The proper value.
  */
-GENERIC_FIXUP_FUNC(fixupRegValue, insn->regBase,    MODRM_REG)
-GENERIC_FIXUP_FUNC(fixupRMValue,  insn->eaRegBase,  EA_REG)
+GENERIC_FIXUP_FUNC(fixupRegValue, insn->regBase,    MODRM_REG, 0x1f)
+GENERIC_FIXUP_FUNC(fixupRMValue,  insn->eaRegBase,  EA_REG,    0xf)
 
 /*
  * fixupReg - Consults an operand specifier to determine which of the

Added: llvm/trunk/test/MC/Disassembler/X86/invalid-EVEX-R2.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/Disassembler/X86/invalid-EVEX-R2.txt?rev=333728&view=auto
==============================================================================
--- llvm/trunk/test/MC/Disassembler/X86/invalid-EVEX-R2.txt (added)
+++ llvm/trunk/test/MC/Disassembler/X86/invalid-EVEX-R2.txt Thu May 31 23:11:29 2018
@@ -0,0 +1,4 @@
+# RUN: llvm-mc --disassemble %s -triple=x86_64-apple-darwin9 2>&1 | grep "invalid instruction encoding"
+
+# This instruction would decode as vcvtsd2usi if the EVEX.R' field weren't 0.
+0x62 0xe1 0xff 0x08 0x79 0xc0