[X86] Fix handling of maskmovdqu in x32 differently

[hvdijk]

Summary

This reverts the functional changes of D103427 but keeps its tests, and reimplements the functionality by reusing the existing 32-bit MASKMOVDQU and VMASKMOVDQU instructions as suggested by skan in review. These instructions were previously predicated on Not64BitMode. This reimplementation restores the disassembly of a class of instructions, which will see a test added in followup patch D122449.

These instructions are in 64-bit mode special cased in X86MCInstLower::Lower, because we use flags with one meaning for subtly different things: we have an AdSize32 class which indicates both that the instruction needs a 0x67 prefix and that the text form of the instruction implies a 0x67 prefix. These instructions are special in needing a 0x67 prefix but having a text form that does *not* imply a 0x67 prefix, so we encode this in MCInst as an instruction that has an explicit address size override.

Note that originally VMASKMOVDQU64 was special cased to be excluded from disassembly, as we cannot distinguish between VMASKMOVDQU and VMASKMOVDQU64 and rely on the fact that these are indistinguishable, or close enough to it, at the MCInst level that it does not matter which we use. Because VMASKMOVDQU now receives special casing, even though it does not make a difference in the current implementation, as a precaution VMASKMOVDQU is excluded from disassembly rather than VMASKMOVDQU64.

[skan]

I believe you can come up this patch independently. But I did make some suggestion about potential solutions in D103427 and prove it in D122537. Would you mind adding me as the co-author and reviewer?

[hvdijk]

In D122540#3412980, @skan wrote:

I believe you can come up this patch independently. But I did make some suggestion about potential solutions in D103427 and prove it in D122537. Would you mind adding me as the co-author and reviewer?

The idea to reuse MASKMOVDQU and VMASKMOVDQU did come from you, the summary should mention that, sure. Edited, I hope that looks okay to you.

And anyone is always welcome to add themself as a reviewer, please feel free to. I would prefer someone else who was completely uninvolved with the implementation to review this as well though, in case there is something we both missed.

[RKSimon]

The summary mentions fixes, but there are no extra tests to show the fix?

[hvdijk]

In D122540#3413415, @RKSimon wrote:

The summary mentions fixes, but there are no extra tests to show the fix?

I referenced skan's D122449 in the summary, that change adds the test that fails on main but passes after this change is applied.

[skan]

llvm/lib/Target/X86/X86InstrSSE.td

4000

Please add comments in the TD file about why you set this instruction isAsmParserOnly.
(see example in X86InstrTSX.td)

[hvdijk]

llvm/lib/Target/X86/X86InstrSSE.td

4000

Comment added, the wording is based on the comment that was originally there prior to D103427 and the error we get when we do not mark it isAsmParserOnly.

[skan]

llvm/lib/Target/X86/X86InstrSSE.td

4000–4001

The comment here is not correct. The disassembler knows the mode 16-bit/32-bit/64-bit when decoding an instruction, and VEX prefix does change the instruction context. I believe the conflict is b/c the only difference between the encodings of VMASKMOVDQU and VMASKMOVDQU64 is a address-size prefix.

[hvdijk]

llvm/lib/Target/X86/X86InstrSSE.td

4000–4001

The comment that we originally had was

// Special case since there is no attribute class for 64-bit and VEX
if (Name == "VMASKMOVDQU64") {
  ShouldBeEmitted = false;
  return;
}

Are you saying that this old comment was also wrong? If so, I will check in more detail what it should be. If not, I will need a bit more help in understanding how the new comment is different in meaning from the old one.

[skan]

llvm/lib/Target/X86/X86InstrSSE.td

4000–4001

Maybe I misunderstood the old comment here, which was added in llvm-svn: 201299. Hi @craig.topper, could you help decide if this comment needs to be updated.

[skan]

llvm/lib/Target/X86/X86InstrSSE.td

4000–4001

The comment that we originally had was

// Special case since there is no attribute class for 64-bit and VEX
if (Name == "VMASKMOVDQU64") {
  ShouldBeEmitted = false;
  return;
}

Are you saying that this old comment was also wrong? If so, I will check in more detail what it should be. If not, I will need a bit more help in understanding how the new comment is different in meaning from the old one.

I suggest the following comments:

// VMASKMOVDQU and VMASKMOVDQU64 differ only in the
// presence of the AdSize prefix. However, the disassembler doesn't
// care about that difference in the instruction definition; it
// handles 32-bit vs. 64-bit addressing for itself based purely
// on the 0x67 prefix and the CPU mode.

[hvdijk]

llvm/lib/Target/X86/X86InstrSSE.td

4000–4001

With respect, I already expressed my frustration earlier already on taking over something that someone else is already working on and doing it yourself. I get that the intent is to be helpful but it goes beyond help, the effect it had before was to tell me "the work you have done was a waste of time, we are better off if you throw that away" and that is the effect it is again having now.

I will wait for the clarification on whether the original comment was correct and whether my version of it accurately reflects the original meaning, and change it if needed.

[skan]

llvm/lib/Target/X86/X86InstrSSE.td

4000–4001

I'm confused by your comment, are you trying to say that I shouldn't point out what might be the correct implementation in the review, but only what's wrong?

I already expressed my frustration earlier already on taking over something that someone else is already working on and doing it yourself.

To be clear, if you read the comments under D103427 carefully, (https://reviews.llvm.org/D103427#inline-1170883) I could have raised patch D122537 earlier. The reason I didn't do this is because I understand that every author wants to fix their own bugs.

You asked for my minds in comments https://reviews.llvm.org/D103427#inline-1171752 first. And then I proposed the patch D122537 to illustrate my thoughts.
Finally that patch was not updated and was abandoned b/c it was duplicated w/ this one for respect.

Of course, we will wait for the response from craig b/c I just made a suggestion here accoding to my understanding of disassmbler.

I'm amazed that we perceive these things so differently.

Please let me know if there is something about my behavior that is not in compliance with the review's conventions.

[craig.topper]

llvm/lib/Target/X86/X86InstrSSE.td

4000–4001

At the time that comment was written the there was no AdSize64 on the MASKMOVDQU64 or VMASKMOVDQU64 instructions. The only differences between them that the tablegen code would look at was the Not64BitMode and In64BitMode predicates. There were no IC_64BIT_VEX* ENUM_ENTRY in X86DisassemblerDecoderCommon.h. So there was no way for the tables to differentiate them.

[craig.topper]

llvm/lib/Target/X86/X86InstrSSE.td

4000–4001

I think the missing IC_64BIT_VEX was what I meant by "attribute class"

[hvdijk]

llvm/lib/Target/X86/X86InstrSSE.td

4000–4001

I hope you are okay with me responding out of the order in your message, I think it is easier to read this way.

I'm amazed that we perceive these things so differently.

I know, it's a weird and wonderful thing how no two people are alike, but boy can it make communication difficult. :)

[...] I could have raised patch D122537 earlier. The reason I didn't do this is because I understand that every author wants to fix their own bugs.

I know some people feel that way, but for myself: if I mess up in a commit and you push a fix, I would be happy with that. I would be annoyed that I messed up, but I would be annoyed regardless of whether I am the one who fixes it. That's not the issue for me. What happened here is that I asked in advance if I could have the time to look into the bug and work on a fix, and you said you were okay with that. Then, once I actually started the work, I wanted to finish it too. I would feel the same way if I started work on any bug, regardless of whether it was caused by myself or someone else.

I'm confused by your comment, are you trying to say that I shouldn't point out what might be the correct implementation in the review, but only what's wrong?

If you have thoughts on what is correct, please do share. It may not come across that way and I apologise for that, but I really do appreciate it. If you do so though, I would still like to actually understand the problem, and come up with a patch to address the problem. When you express your thoughts in a way that bypasses that process by posting the end result instead, the only thing I can do with it is just copy and paste what you wrote. That does not help me understand the problem, and when I then finally do understand the problem, also no longer allows me to come up with a patch for it because that part is done already. That applies to the wording of the comment too.

Please let me know if there is something about my behavior that is not in compliance with the review's conventions.

I do not think you did anything that is not in line with LLVM policy, I think these sorts of interpersonal issues are not covered by policy and they probably should not be. Everybody is different, and as long as we have no reason to doubt the good intentions of other contributors, we should try to respond to them in a way that works for them. Sometimes, like in this particular case, we (I do include myself in that) mess up with that, we get a better understanding of what the other contributors are like, and we can change our behaviour and our expectations accordingly for next time.

Of course, we will wait for the response from craig b/c I just made a suggestion here accoding to my understanding of disassmbler.

That sounds good, you tracked the original comment to him (thanks for that), so let's give him a chance to comment on it.

[hvdijk]

llvm/lib/Target/X86/X86InstrSSE.td

4000–4001

Thanks, combining that with what @skan wrote earlier, I think that would mean the comment was correct at the time, but became outdated and never got updated. If so, if we reinstate the comment (even if elsewhere) that is a good time to fix that. I will check to make sure my understanding is correct.

[skan]

llvm/lib/Target/X86/X86InstrSSE.td

4000–4001

[...] I could have raised patch D122537 earlier. The reason I didn't do this is because I understand that every author wants to fix their own bugs.

I know some people feel that way, but for myself: if I mess up in a commit and you push a fix, I would be happy with that. I would be annoyed that I messed up, but I would be annoyed regardless of whether I am the one who fixes it. That's not the issue for me. What happened here is that I asked in advance if I could have the time to look into the bug and work on a fix, and you said you were okay with that. Then, once I actually started the work, I wanted to finish it too. I would feel the same way if I started work on any bug, regardless of whether it was caused by myself or someone else.

I didn't propose the patch until you commented "Is that about what you had in mind too?".

I think a simple "No" for this question is unfriendly, it seems like I'm reluctant to share my thoughts. For me, this question sounds like it's saying, if not, please say how you want to implemement it.

I'm confused by your comment, are you trying to say that I shouldn't point out what might be the correct implementation in the review, but only what's wrong?

If you have thoughts on what is correct, please do share. It may not come across that way and I apologise for that, but I really do appreciate it. If you do so though, I would still like to actually understand the problem, and come up with a patch to address the problem. When you express your thoughts in a way that bypasses that process by posting the end result instead, the only thing I can do with it is just copy and paste what you wrote. That does not help me understand the problem, and when I then finally do understand the problem, also no longer allows me to come up with a patch for it because that part is done already. That applies to the wording of the comment too.

I don't think my posted comment is end result, that's why I use the word "suggest". You can organize it in your own words and correct inaccuracies. And my intention is to help you understood the problem more quickly.

[skan]

Anyway, let's focus on the patch itself and ignore the misunderstandings caused by culture or personality during the communication process. Our purpose is to fix the issue and improve the code quality.

[hvdijk]

llvm/lib/Target/X86/X86InstrSSE.td

4000–4001

Having now had the time to look into this, I think the comment was right and remained right until this change. (Technically, it could be argued to remain accurate even with this change, but only because it is slightly ambiguous and the required interpretation of the comment to make it correct has changed. That means we should treat it as no longer accurate.)

Originally, VMASKMOVDQU was only defined for 32-bit CPU mode, and VMASKMOVDQU64 was only defined for 64-bit CPU mode. However like @craig.topper wrote there is no separate IC_64BIT_VEX so we would not be able to use this to distinguish between the two instructions for decoding. (In response to "The disassembler knows the mode 16-bit/32-bit/64-bit when decoding an instruction, and VEX prefix does change the instruction context." -- Yes, but the VEX prefix changes the instruction context to IC_VEX unconditionally, dropping the distinction between 32-bit vs 64-bit.)

Now, VMASKMOVDQU is defined for both 32-bit and 64-bit CPU mode, and VMASKMOVDQU64 is defined only for 64-bit CPU mode. This means we cannot use CPU mode to disambiguate anyway. These instructions do differ, as @skan wrote, in address size (32-bit vs 64-bit), which is normally also handled by having different instruction contexts, but in the case of VEX those different instruction contexts are not present either so we still cannot use that to disambiguate for decoding.

I believe the comment is correct and clearer like this, does this look okay?

[skan]

LGTM

[hvdijk]

I mentioned that I'd prefer to get another person to review this as well but in the interest of just getting the bug fixed, I'll merge this tomorrow if there is no more feedback.

[RKSimon]

LGTM

llvm/include/llvm/Support/X86DisassemblerDecoderCommon.h

ENUM_ENTRY(IC_64BIT_REXW_XD,      7,  "Just as meaningful as "               \
                                         "IC_64BIT_REXW_XS")                    \
   ENUM_ENTRY(IC_64BIT_REXW_OPSIZE,  8,  "The Dynamic Duo!  Prefer over all "   \
                                         "else because this changes most "      \
                                         "operands' meaning")                   \
   ENUM_ENTRY(IC_VEX,                1,  "requires a VEX prefix")               \
   ENUM_ENTRY(IC_VEX_XS,             2,  "requires VEX and the XS prefix")      \
   ENUM_ENTRY(IC_VEX_XD,             2,  "requires VEX and the XD prefix")      \
   ENUM_ENTRY(IC_VEX_OPSIZE,         2,  "requires VEX and the OpSize prefix")  \
-  ENUM_ENTRY(IC_64BIT_VEX_OPSIZE,        4, "requires 64-bit mode and VEX")         \
-  ENUM_ENTRY(IC_64BIT_VEX_OPSIZE_ADSIZE, 5, "requires 64-bit mode, VEX, and AdSize")\
   ENUM_ENTRY(IC_VEX_W,              3,  "requires VEX and the W prefix")       \
   ENUM_ENTRY(IC_VEX_W_XS,           4,  "requires VEX, W, and XS prefix")      \
   ENUM_ENTRY(IC_VEX_W_XD,           4,  "requires VEX, W, and XD prefix")      \
   ENUM_ENTRY(IC_VEX_W_OPSIZE,       4,  "requires VEX, W, and OpSize")         \
   ENUM_ENTRY(IC_VEX_L,              3,  "requires VEX and the L prefix")       \
   ENUM_ENTRY(IC_VEX_L_XS,           4,  "requires VEX and the L and XS prefix")\
   ENUM_ENTRY(IC_VEX_L_XD,           4,  "requires VEX and the L and XD prefix")\
   ENUM_ENTRY(IC_VEX_L_OPSIZE,       4,  "requires VEX, L, and OpSize")         \

llvm/lib/Target/X86/X86InstrSSE.td

 
 } // ExeDomain = SSEPackedInt
 
 //===---------------------------------------------------------------------===//
 // SSE2 - Conditional Store
 //===---------------------------------------------------------------------===//
 
 let ExeDomain = SSEPackedInt, SchedRW = [SchedWriteVecMoveLS.XMM.MR] in {
-let Uses = [EDI], Predicates = [HasAVX,Not64BitMode] in
+let Uses = [EDI], Predicates = [HasAVX], isAsmParserOnly = 1 in
 def VMASKMOVDQU : VPDI<0xF7, MRMSrcReg, (outs),
            (ins VR128:$src, VR128:$mask),
            "maskmovdqu\t{$mask, $src|$src, $mask}",
            [(int_x86_sse2_maskmov_dqu VR128:$src, VR128:$mask, EDI)]>,
            VEX, VEX_WIG;
 let Uses = [RDI], Predicates = [HasAVX,In64BitMode] in
 def VMASKMOVDQU64 : VPDI<0xF7, MRMSrcReg, (outs),
            (ins VR128:$src, VR128:$mask),
            "maskmovdqu\t{$mask, $src|$src, $mask}",
            [(int_x86_sse2_maskmov_dqu VR128:$src, VR128:$mask, RDI)]>,
-           VEX, VEX_WIG, AdSize64;
-let Uses = [EDI], Predicates = [HasAVX,In64BitMode] in
-def VMASKMOVDQUX32 : VPDI<0xF7, MRMSrcReg, (outs),
-           (ins VR128:$src, VR128:$mask), "",
-           [(int_x86_sse2_maskmov_dqu VR128:$src, VR128:$mask, EDI)]>,
-           VEX, VEX_WIG, AdSize32 {
-  let AsmString = "addr32 vmaskmovdqu\t{$mask, $src|$src, $mask}";
-  let AsmVariantName = "NonParsable";
-}
+           VEX, VEX_WIG;
 
-let Uses = [EDI], Predicates = [UseSSE2,Not64BitMode] in
+let Uses = [EDI], Predicates = [UseSSE2] in
 def MASKMOVDQU : PDI<0xF7, MRMSrcReg, (outs), (ins VR128:$src, VR128:$mask),
            "maskmovdqu\t{$mask, $src|$src, $mask}",
            [(int_x86_sse2_maskmov_dqu VR128:$src, VR128:$mask, EDI)]>;
 let Uses = [RDI], Predicates = [UseSSE2,In64BitMode] in
 def MASKMOVDQU64 : PDI<0xF7, MRMSrcReg, (outs), (ins VR128:$src, VR128:$mask),
            "maskmovdqu\t{$mask, $src|$src, $mask}",
-           [(int_x86_sse2_maskmov_dqu VR128:$src, VR128:$mask, RDI)]>,
-           AdSize64;
-let Uses = [EDI], Predicates = [UseSSE2,In64BitMode] in
-def MASKMOVDQUX32 : PDI<0xF7, MRMSrcReg, (outs), (ins VR128:$src, VR128:$mask),
-           "addr32 maskmovdqu\t{$mask, $src|$src, $mask}",
-           [(int_x86_sse2_maskmov_dqu VR128:$src, VR128:$mask, EDI)]>,
-           AdSize32 {
-  let AsmVariantName = "NonParsable";
-}
+           [(int_x86_sse2_maskmov_dqu VR128:$src, VR128:$mask, RDI)]>;
 
 } // ExeDomain = SSEPackedInt
 
 //===---------------------------------------------------------------------===//
 // SSE2 - Move Doubleword/Quadword
 //===---------------------------------------------------------------------===//
 
 //===---------------------------------------------------------------------===//

llvm/lib/Target/X86/X86MCInstLower.cpp

case X86::VCMPSSrr: {
     break;
   }
 
   case X86::VMOVHLPSrr:
   case X86::VUNPCKHPDrr:
     // These are not truly commutable so hide them from the default case.
     break;
 
+  case X86::MASKMOVDQU:
+  case X86::VMASKMOVDQU:
+    if (AsmPrinter.getSubtarget().is64Bit())
+      OutMI.setFlags(X86::IP_HAS_AD_SIZE);
+    break;
+
   default: {
     // If the instruction is a commutable arithmetic instruction we might be
     // able to commute the operands to get a 2 byte VEX prefix.
     uint64_t TSFlags = MI->getDesc().TSFlags;
     if (MI->getDesc().isCommutable() &&
         (TSFlags & X86II::EncodingMask) == X86II::VEX &&
         (TSFlags & X86II::OpMapMask) == X86II::TB &&
         (TSFlags & X86II::FormMask) == X86II::MRMSrcReg &&

llvm/lib/Target/X86/X86ScheduleBtVer2.td

 //  SSE2/AVX Store Selected Bytes of Double Quadword - (V)MASKMOVDQ
 ///////////////////////////////////////////////////////////////////////////////
 
 def JWriteMASKMOVDQU: SchedWriteRes<[JFPU0, JFPA, JFPU1, JSTC, JLAGU, JSAGU, JALU01]> {
   let Latency = 34;
   let ResourceCycles = [1, 1, 2, 2, 2, 16, 42];
   let NumMicroOps = 63;
 }
-def : InstRW<[JWriteMASKMOVDQU], (instrs MASKMOVDQU, MASKMOVDQU64, MASKMOVDQUX32,
-                                         VMASKMOVDQU, VMASKMOVDQU64, VMASKMOVDQUX32)>;
+def : InstRW<[JWriteMASKMOVDQU], (instrs MASKMOVDQU, MASKMOVDQU64,
+                                         VMASKMOVDQU, VMASKMOVDQU64)>;
 
 ///////////////////////////////////////////////////////////////////////////////
 //  SchedWriteVariant definitions.
 ///////////////////////////////////////////////////////////////////////////////
 
 def JWriteZeroLatency : SchedWriteRes<[]> {
   let Latency = 0;
 }

llvm/utils/TableGen/X86DisassemblerTables.cpp

return inheritsFrom(child, IC_64BIT_OPSIZE) ||
            inheritsFrom(child, IC_OPSIZE_ADSIZE);
   case IC_ADSIZE:
     return (noPrefix && inheritsFrom(child, IC_OPSIZE_ADSIZE, noPrefix));
   case IC_OPSIZE_ADSIZE:
     return false;
   case IC_64BIT_ADSIZE:
     return (noPrefix && inheritsFrom(child, IC_64BIT_OPSIZE_ADSIZE, noPrefix));
   case IC_64BIT_OPSIZE_ADSIZE:
-    return (noPrefix &&
-            inheritsFrom(child, IC_64BIT_VEX_OPSIZE_ADSIZE, noPrefix));
+    return false;
   case IC_XD:
     return inheritsFrom(child, IC_64BIT_XD);
   case IC_XS:
     return inheritsFrom(child, IC_64BIT_XS);
   case IC_XD_OPSIZE:
     return inheritsFrom(child, IC_64BIT_XD_OPSIZE);
   case IC_XS_OPSIZE:
     return inheritsFrom(child, IC_64BIT_XS_OPSIZE);
   case IC_XD_ADSIZE:
     return inheritsFrom(child, IC_64BIT_XD_ADSIZE);
   case IC_XS_ADSIZE:
     return inheritsFrom(child, IC_64BIT_XS_ADSIZE);
   case IC_64BIT_REXW:
     return((noPrefix && inheritsFrom(child, IC_64BIT_REXW_XS, noPrefix)) ||
            (noPrefix && inheritsFrom(child, IC_64BIT_REXW_XD, noPrefix)) ||
            (noPrefix && inheritsFrom(child, IC_64BIT_REXW_OPSIZE, noPrefix)) ||
            (!AdSize64 && inheritsFrom(child, IC_64BIT_REXW_ADSIZE)));
   case IC_64BIT_OPSIZE:
     return inheritsFrom(child, IC_64BIT_REXW_OPSIZE) ||
            (!AdSize64 && inheritsFrom(child, IC_64BIT_OPSIZE_ADSIZE)) ||
-           (!AdSize64 && inheritsFrom(child, IC_64BIT_REXW_ADSIZE)) ||
-           (!AdSize64 && inheritsFrom(child, IC_64BIT_VEX_OPSIZE_ADSIZE));
+           (!AdSize64 && inheritsFrom(child, IC_64BIT_REXW_ADSIZE));
   case IC_64BIT_XD:
-    return (inheritsFrom(child, IC_64BIT_REXW_XD) ||
-            (!AdSize64 && inheritsFrom(child, IC_64BIT_XD_ADSIZE)));
+    return(inheritsFrom(child, IC_64BIT_REXW_XD) ||
   case IC_64BIT_XS:
     return(inheritsFrom(child, IC_64BIT_REXW_XS) ||
            (!AdSize64 && inheritsFrom(child, IC_64BIT_XS_ADSIZE)));
   case IC_64BIT_XD_OPSIZE:
   case IC_64BIT_XS_OPSIZE:
     return false;
   case IC_64BIT_XD_ADSIZE:
   case IC_64BIT_XS_ADSIZE:
return (VEX_LIG && VEX_WIG && inheritsFrom(child, IC_VEX_L_W_XS)) ||
            (VEX_LIG && inheritsFrom(child, IC_VEX_L_XS));
   case IC_VEX_XD:
     return (VEX_LIG && VEX_WIG && inheritsFrom(child, IC_VEX_L_W_XD)) ||
            (VEX_WIG && inheritsFrom(child, IC_VEX_W_XD)) ||
            (VEX_LIG && inheritsFrom(child, IC_VEX_L_XD));
   case IC_VEX_OPSIZE:
     return (VEX_LIG && VEX_WIG && inheritsFrom(child, IC_VEX_L_W_OPSIZE)) ||
            (VEX_WIG && inheritsFrom(child, IC_VEX_W_OPSIZE)) ||
-           (VEX_LIG && inheritsFrom(child, IC_VEX_L_OPSIZE)) ||
-           inheritsFrom(child, IC_64BIT_VEX_OPSIZE);
-  case IC_64BIT_VEX_OPSIZE:
-    return inheritsFrom(child, IC_64BIT_VEX_OPSIZE_ADSIZE);
-  case IC_64BIT_VEX_OPSIZE_ADSIZE:
-    return false;
+           (VEX_LIG && inheritsFrom(child, IC_VEX_L_OPSIZE));
   case IC_VEX_W:
     return VEX_LIG && inheritsFrom(child, IC_VEX_L_W);
   case IC_VEX_W_XS:
     return VEX_LIG && inheritsFrom(child, IC_VEX_L_W_XS);
   case IC_VEX_W_XD:
     return VEX_LIG && inheritsFrom(child, IC_VEX_L_W_XD);
   case IC_VEX_W_OPSIZE:
     return VEX_LIG && inheritsFrom(child, IC_VEX_L_W_OPSIZE);
void DisassemblerTables::emitContextTable(raw_ostream &o, unsigned &i) const {
   i++;
 
   for (unsigned index = 0; index < ATTR_max; ++index) {
     o.indent(i * 2);
 
     if ((index & ATTR_EVEX) || (index & ATTR_VEX) || (index & ATTR_VEXL)) {
       if (index & ATTR_EVEX)
         o << "IC_EVEX";
-      else if ((index & (ATTR_64BIT | ATTR_VEXL | ATTR_REXW | ATTR_OPSIZE)) ==
-               (ATTR_64BIT | ATTR_OPSIZE))
-        o << "IC_64BIT_VEX";
       else
         o << "IC_VEX";
 
       if ((index & ATTR_EVEX) && (index & ATTR_EVEXL2))
         o << "_L2";
       else if (index & ATTR_VEXL)
         o << "_L";
 
       if (index & ATTR_REXW)
         o << "_W";
 
-      if (index & ATTR_OPSIZE) {
+      if (index & ATTR_OPSIZE)
         o << "_OPSIZE";
-        if ((index & (ATTR_64BIT | ATTR_EVEX | ATTR_VEX | ATTR_VEXL |
-                      ATTR_REXW | ATTR_ADSIZE)) ==
-            (ATTR_64BIT | ATTR_VEX | ATTR_ADSIZE))
-          o << "_ADSIZE";
-      } else if (index & ATTR_XD)
+      else if (index & ATTR_XD)
         o << "_XD";
       else if (index & ATTR_XS)
         o << "_XS";
 
       if ((index & ATTR_EVEX)) {
         if (index & ATTR_EVEXKZ)
           o << "_KZ";
         else if (index & ATTR_EVEXK)
           o << "_K";
 
         if (index & ATTR_EVEXB)
           o << "_B";
       }
-    } else if ((index & ATTR_64BIT) && (index & ATTR_REXW) && (index & ATTR_XS))
+    }
+    else if ((index & ATTR_64BIT) && (index & ATTR_REXW) && (index & ATTR_XS))
       o << "IC_64BIT_REXW_XS";
     else if ((index & ATTR_64BIT) && (index & ATTR_REXW) && (index & ATTR_XD))
       o << "IC_64BIT_REXW_XD";
     else if ((index & ATTR_64BIT) && (index & ATTR_REXW) &&
              (index & ATTR_OPSIZE))
       o << "IC_64BIT_REXW_OPSIZE";
     else if ((index & ATTR_64BIT) && (index & ATTR_REXW) &&
              (index & ATTR_ADSIZE))

llvm/utils/TableGen/X86RecognizableInstr.cpp

if (HasVEX_L && HasVEX_W) {
       else {
         errs() << "Instruction does not use a prefix: " << Name << "\n";
         llvm_unreachable("Invalid prefix");
       }
     } else if (OpPrefix == X86Local::PD && HasVEX_L)
       insnContext = IC_VEX_L_OPSIZE;
     else if (OpPrefix == X86Local::PD && HasVEX_W)
       insnContext = IC_VEX_W_OPSIZE;
-    else if (OpPrefix == X86Local::PD && Is64Bit &&
-             AdSize == X86Local::AdSize32)
-      insnContext = IC_64BIT_VEX_OPSIZE_ADSIZE;
-    else if (OpPrefix == X86Local::PD && Is64Bit)
-      insnContext = IC_64BIT_VEX_OPSIZE;
     else if (OpPrefix == X86Local::PD)
       insnContext = IC_VEX_OPSIZE;
     else if (HasVEX_L && OpPrefix == X86Local::XS)
       insnContext = IC_VEX_L_XS;
     else if (HasVEX_L && OpPrefix == X86Local::XD)
       insnContext = IC_VEX_L_XD;
     else if (HasVEX_W && OpPrefix == X86Local::XS)
       insnContext = IC_VEX_W_XS;