[X86] VEX/EVEX prefix doesn't work for inline assembly.

For now, we lost the encoding information if we using inline assembly.
The encoding for the inline assembly will keep default even if we add
the vex/evex prefix.

Differential Revision: https://reviews.llvm.org/D90009

clang/test/CodeGen/X86/att-inline-asm-prefix.c

@@ -0,0 +1,25 @@
+// RUN:%clang_cc1 %s -ferror-limit 0 -triple=x86_64-pc -target-feature +avx512f -target-feature +avx2 -target-feature +avx512vl -S -o -  | FileCheck %s -check-prefix CHECK
+
+// This test is to check if the prefix in inline assembly is correctly
+// preserved.
+
+void check_inline_prefix(void) {
+  __asm__ (
+// CHECK: vcvtps2pd %xmm0, %xmm1
+// CHECK: {vex} vcvtps2pd %xmm0, %xmm1
+// CHECK: {vex2} vcvtps2pd %xmm0, %xmm1
+// CHECK: {vex3} vcvtps2pd %xmm0, %xmm1
+// CHECK: {evex} vcvtps2pd %xmm0, %xmm1
+// CHECK: movl $1, (%rax)
+// CHECK: {disp8}  movl $1, (%rax)
+// CHECK: {disp32} movl $1, (%rax)
+    "vcvtps2pd %xmm0, %xmm1\n\t"
+    "{vex} vcvtps2pd %xmm0, %xmm1\n\t"
+    "{vex2} vcvtps2pd %xmm0, %xmm1\n\t"
+    "{vex3} vcvtps2pd %xmm0, %xmm1\n\t"
+    "{evex} vcvtps2pd %xmm0, %xmm1\n\t"
+    "movl $1, (%rax)\n\t"
+    "{disp8} movl $1, (%rax)\n\t"
+    "{disp32} movl $1, (%rax)\n\t"
+  );
+}

llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp

@@ -83,6 +83,7 @@ class X86AsmParser : public MCTargetAsmParser {
   enum VEXEncoding {
     VEXEncoding_Default,
     VEXEncoding_VEX,
+    VEXEncoding_VEX2,
     VEXEncoding_VEX3,
     VEXEncoding_EVEX,
   };
@@ -2818,8 +2819,10 @@ bool X86AsmParser::ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
         return Error(Parser.getTok().getLoc(), "Expected '}'");
       Parser.Lex(); // Eat curly.
 
-      if (Prefix == "vex" || Prefix == "vex2")
+      if (Prefix == "vex")
         ForcedVEXEncoding = VEXEncoding_VEX;
+      else if (Prefix == "vex2")
+        ForcedVEXEncoding = VEXEncoding_VEX2;
       else if (Prefix == "vex3")
         ForcedVEXEncoding = VEXEncoding_VEX3;
       else if (Prefix == "evex")
@@ -3837,6 +3840,7 @@ unsigned X86AsmParser::checkTargetMatchPredicate(MCInst &Inst) {
     return Match_Unsupported;
 
   if ((ForcedVEXEncoding == VEXEncoding_VEX ||
+       ForcedVEXEncoding == VEXEncoding_VEX2 ||
        ForcedVEXEncoding == VEXEncoding_VEX3) &&
       (MCID.TSFlags & X86II::EncodingMask) != X86II::VEX)
     return Match_Unsupported;
@@ -3879,10 +3883,16 @@ bool X86AsmParser::MatchAndEmitATTInstruction(SMLoc IDLoc, unsigned &Opcode,
 
   MCInst Inst;
 
-  // If VEX3 encoding is forced, we need to pass the USE_VEX3 flag to the
-  // encoder.
-  if (ForcedVEXEncoding == VEXEncoding_VEX3)
+  // If VEX/EVEX encoding is forced, we need to pass the USE_* flag to the
+  // encoder and printer.
+  if (ForcedVEXEncoding == VEXEncoding_VEX)
+    Prefixes |= X86::IP_USE_VEX;
+  else if (ForcedVEXEncoding == VEXEncoding_VEX2)
+    Prefixes |= X86::IP_USE_VEX2;
+  else if (ForcedVEXEncoding == VEXEncoding_VEX3)
     Prefixes |= X86::IP_USE_VEX3;
+  else if (ForcedVEXEncoding == VEXEncoding_EVEX)
+    Prefixes |= X86::IP_USE_EVEX;
 
   // Set encoded flags for {disp8} and {disp32}.
   if (ForcedDispEncoding == DispEncoding_Disp8)

llvm/lib/Target/X86/MCTargetDesc/X86BaseInfo.h

@@ -55,15 +55,18 @@ namespace X86 {
   /// The constants to describe instr prefixes if there are
   enum IPREFIXES {
     IP_NO_PREFIX = 0,
-    IP_HAS_OP_SIZE = 1,
-    IP_HAS_AD_SIZE = 2,
-    IP_HAS_REPEAT_NE = 4,
-    IP_HAS_REPEAT = 8,
-    IP_HAS_LOCK = 16,
-    IP_HAS_NOTRACK = 32,
-    IP_USE_VEX3 = 64,
-    IP_USE_DISP8 = 128,
-    IP_USE_DISP32 = 256,
+    IP_HAS_OP_SIZE =   1U << 0,
+    IP_HAS_AD_SIZE =   1U << 1,
+    IP_HAS_REPEAT_NE = 1U << 2,
+    IP_HAS_REPEAT =    1U << 3,
+    IP_HAS_LOCK =      1U << 4,
+    IP_HAS_NOTRACK =   1U << 5,
+    IP_USE_VEX =       1U << 6,
+    IP_USE_VEX2 =      1U << 7,
+    IP_USE_VEX3 =      1U << 8,
+    IP_USE_EVEX =      1U << 9,
+    IP_USE_DISP8 =     1U << 10,
+    IP_USE_DISP32 =    1U << 11,
   };
 
   enum OperandType : unsigned {

llvm/lib/Target/X86/MCTargetDesc/X86InstPrinterCommon.cpp

@@ -346,6 +346,21 @@ void X86InstPrinterCommon::printInstFlags(const MCInst *MI, raw_ostream &O) {
     O << "\trepne\t";
   else if (Flags & X86::IP_HAS_REPEAT)
     O << "\trep\t";
+
+  // These all require a pseudo prefix
+  if (Flags & X86::IP_USE_VEX)
+    O << "\t{vex}";
+  else if (Flags & X86::IP_USE_VEX2)
+    O << "\t{vex2}";
+  else if (Flags & X86::IP_USE_VEX3)
+    O << "\t{vex3}";
+  else if (Flags & X86::IP_USE_EVEX)
+    O << "\t{evex}";
+
+  if (Flags & X86::IP_USE_DISP8)
+    O << "\t{disp8}";
+  else if (Flags & X86::IP_USE_DISP32)
+    O << "\t{disp32}";
 }
 
 void X86InstPrinterCommon::printVKPair(const MCInst *MI, unsigned OpNo,