aarch64: support target-specific .req assembler directive

Based on the support for .req on ARM. The aarch64 variant has to keep track if
the alias register was a vector register (v0-31) or a general purpose or
VFP/Advanced SIMD ([bhsdq]0-31) register.

Patch by Janne Grunau!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212161 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

@@ -43,6 +43,9 @@ private:
   MCSubtargetInfo &STI;
   MCAsmParser &Parser;
 
+  // Map of register aliases registers via the .req directive.
+  StringMap<std::pair<bool, unsigned> > RegisterReqs;
+
   AArch64TargetStreamer &getTargetStreamer() {
     MCTargetStreamer &TS = *getParser().getStreamer().getTargetStreamer();
     return static_cast<AArch64TargetStreamer &>(TS);
@@ -56,6 +59,7 @@ private:
   bool parseSysAlias(StringRef Name, SMLoc NameLoc, OperandVector &Operands);
   AArch64CC::CondCode parseCondCodeString(StringRef Cond);
   bool parseCondCode(OperandVector &Operands, bool invertCondCode);
+  unsigned matchRegisterNameAlias(StringRef Name, bool isVector);
   int tryParseRegister();
   int tryMatchVectorRegister(StringRef &Kind, bool expected);
   bool parseRegister(OperandVector &Operands);
@@ -74,6 +78,9 @@ private:
   bool parseDirectiveLOH(StringRef LOH, SMLoc L);
   bool parseDirectiveLtorg(SMLoc L);
 
+  bool parseDirectiveReq(StringRef Name, SMLoc L);
+  bool parseDirectiveUnreq(SMLoc L);
+
   bool validateInstruction(MCInst &Inst, SmallVectorImpl<SMLoc> &Loc);
   bool MatchAndEmitInstruction(SMLoc IDLoc, unsigned &Opcode,
                                OperandVector &Operands, MCStreamer &Out,
@@ -1825,6 +1832,26 @@ bool AArch64AsmParser::ParseRegister(unsigned &RegNo, SMLoc &StartLoc,
   return (RegNo == (unsigned)-1);
 }
 
+// Matches a register name or register alias previously defined by '.req'
+unsigned AArch64AsmParser::matchRegisterNameAlias(StringRef Name,
+                                                  bool isVector) {
+  unsigned RegNum = isVector ? matchVectorRegName(Name)
+                             : MatchRegisterName(Name);
+
+  if (RegNum == 0) {
+    // Check for aliases registered via .req. Canonicalize to lower case.
+    // That's more consistent since register names are case insensitive, and
+    // it's how the original entry was passed in from MC/MCParser/AsmParser.
+    auto Entry = RegisterReqs.find(Name.lower());
+    if (Entry == RegisterReqs.end())
+      return 0;
+    // set RegNum if the match is the right kind of register
+    if (isVector == Entry->getValue().first)
+      RegNum = Entry->getValue().second;
+  }
+  return RegNum;
+}
+
 /// tryParseRegister - Try to parse a register name. The token must be an
 /// Identifier when called, and if it is a register name the token is eaten and
 /// the register is added to the operand list.
@@ -1833,7 +1860,7 @@ int AArch64AsmParser::tryParseRegister() {
   assert(Tok.is(AsmToken::Identifier) && "Token is not an Identifier");
 
   std::string lowerCase = Tok.getString().lower();
-  unsigned RegNum = MatchRegisterName(lowerCase);
+  unsigned RegNum = matchRegisterNameAlias(lowerCase, false);
   // Also handle a few aliases of registers.
   if (RegNum == 0)
     RegNum = StringSwitch<unsigned>(lowerCase)
@@ -1863,7 +1890,8 @@ int AArch64AsmParser::tryMatchVectorRegister(StringRef &Kind, bool expected) {
   // a '.'.
   size_t Start = 0, Next = Name.find('.');
   StringRef Head = Name.slice(Start, Next);
-  unsigned RegNum = matchVectorRegName(Head);
+  unsigned RegNum = matchRegisterNameAlias(Head, true);
+
   if (RegNum) {
     if (Next != StringRef::npos) {
       Kind = Name.slice(Next, StringRef::npos);
@@ -2861,7 +2889,7 @@ AArch64AsmParser::tryParseGPR64sp0Operand(OperandVector &Operands) {
   if (!Tok.is(AsmToken::Identifier))
     return MatchOperand_NoMatch;
 
-  unsigned RegNum = MatchRegisterName(Tok.getString().lower());
+  unsigned RegNum = matchRegisterNameAlias(Tok.getString().lower(), false);
 
   MCContext &Ctx = getContext();
   const MCRegisterInfo *RI = Ctx.getRegisterInfo();
@@ -3078,6 +3106,15 @@ bool AArch64AsmParser::ParseInstruction(ParseInstructionInfo &Info,
              .Case("bnv", "b.nv")
              .Default(Name);
 
+  // First check for the AArch64-specific .req directive.
+  if (Parser.getTok().is(AsmToken::Identifier) &&
+      Parser.getTok().getIdentifier() == ".req") {
+    parseDirectiveReq(Name, NameLoc);
+    // We always return 'error' for this, as we're done with this
+    // statement and don't need to match the 'instruction."
+    return true;
+  }
+
   // Create the leading tokens for the mnemonic, split by '.' characters.
   size_t Start = 0, Next = Name.find('.');
   StringRef Head = Name.slice(Start, Next);
@@ -3857,6 +3894,9 @@ bool AArch64AsmParser::ParseDirective(AsmToken DirectiveID) {
     return parseDirectiveTLSDescCall(Loc);
   if (IDVal == ".ltorg" || IDVal == ".pool")
     return parseDirectiveLtorg(Loc);
+  if (IDVal == ".unreq")
+    return parseDirectiveUnreq(DirectiveID.getLoc());
+
   return parseDirectiveLOH(IDVal, Loc);
 }
 
@@ -3964,6 +4004,59 @@ bool AArch64AsmParser::parseDirectiveLtorg(SMLoc L) {
   return false;
 }
 
+/// parseDirectiveReq
+///  ::= name .req registername
+bool AArch64AsmParser::parseDirectiveReq(StringRef Name, SMLoc L) {
+  Parser.Lex(); // Eat the '.req' token.
+  SMLoc SRegLoc = getLoc();
+  unsigned RegNum = tryParseRegister();
+  bool IsVector = false;
+
+  if (RegNum == static_cast<unsigned>(-1)) {
+    StringRef Kind;
+    RegNum = tryMatchVectorRegister(Kind, false);
+    if (!Kind.empty()) {
+      Error(SRegLoc, "vector register without type specifier expected");
+      return false;
+    }
+    IsVector = true;
+  }
+
+  if (RegNum == static_cast<unsigned>(-1)) {
+    Parser.eatToEndOfStatement();
+    Error(SRegLoc, "register name or alias expected");
+    return false;
+  }
+
+  // Shouldn't be anything else.
+  if (Parser.getTok().isNot(AsmToken::EndOfStatement)) {
+    Error(Parser.getTok().getLoc(), "unexpected input in .req directive");
+    Parser.eatToEndOfStatement();
+    return false;
+  }
+
+  Parser.Lex(); // Consume the EndOfStatement
+
+  auto pair = std::make_pair(IsVector, RegNum);
+  if (RegisterReqs.GetOrCreateValue(Name, pair).getValue() != pair)
+    Warning(L, "ignoring redefinition of register alias '" + Name + "'");
+
+  return true;
+}
+
+/// parseDirectiveUneq
+///  ::= .unreq registername
+bool AArch64AsmParser::parseDirectiveUnreq(SMLoc L) {
+  if (Parser.getTok().isNot(AsmToken::Identifier)) {
+    Error(Parser.getTok().getLoc(), "unexpected input in .unreq directive.");
+    Parser.eatToEndOfStatement();
+    return false;
+  }
+  RegisterReqs.erase(Parser.getTok().getIdentifier().lower());
+  Parser.Lex(); // Eat the identifier.
+  return false;
+}
+
 bool
 AArch64AsmParser::classifySymbolRef(const MCExpr *Expr,
                                     AArch64MCExpr::VariantKind &ELFRefKind,

test/MC/AArch64/dot-req-case-insensitive.s

@@ -0,0 +1,18 @@
+// RUN: llvm-mc -triple=arm64-eabi < %s | FileCheck %s
+_foo:
+        OBJECT .req x2
+        mov x4, OBJECT
+        mov x4, oBjEcT
+        .unreq oBJECT
+
+_foo2:
+        OBJECT .req w5
+        mov w4, OBJECT
+        .unreq OBJECT
+
+// CHECK-LABEL: _foo:
+// CHECK: mov x4, x2
+// CHECK: mov x4, x2
+
+// CHECK-LABEL: _foo2:
+// CHECK: mov w4, w5

test/MC/AArch64/dot-req-diagnostics.s

@@ -0,0 +1,37 @@
+// RUN: not llvm-mc -triple aarch64-none-linux-gnu < %s 2>&1 | FileCheck --check-prefix=CHECK --check-prefix=CHECK-ERROR %s
+
+bar:
+        fred .req x5
+        fred .req x6
+// CHECK-ERROR: warning: ignoring redefinition of register alias 'fred'
+// CHECK-ERROR: fred .req x6
+// CHECK-ERROR: ^
+
+        ada  .req v2.8b
+// CHECK-ERROR: error: vector register without type specifier expected
+// CHECK-ERROR: ada  .req v2.8b
+// CHECK-ERROR:           ^
+
+        bob  .req lisa
+// CHECK-ERROR: error: register name or alias expected
+// CHECK-ERROR: bob  .req lisa
+// CHECK-ERROR:           ^
+
+        lisa .req x1, 23
+// CHECK-ERROR: error: unexpected input in .req directive
+// CHECK-ERROR: lisa .req x1, 23
+// CHECK-ERROR:             ^
+
+        mov  bob, fred
+// CHECK-ERROR: error: invalid operand for instruction
+// CHECK-ERROR: mov  bob, fred
+// CHECK-ERROR:      ^
+
+        .unreq 1
+// CHECK-ERROR: error: unexpected input in .unreq directive.
+// CHECK-ERROR: .unreq 1
+// CHECK-ERROR:        ^
+
+        mov  x1, fred
+// CHECK: mov x1, x5
+// CHECK-NOT: mov x1, x6

test/MC/AArch64/dot-req.s

@@ -0,0 +1,37 @@
+// RUN: llvm-mc -triple=aarch64-none-linux-gnu -show-encoding < %s | FileCheck %s
+
+bar:
+        fred .req x5
+        mov fred, x11
+        .unreq fred
+        fred .req w6
+        mov w1, fred
+
+        bob .req fred
+        ada .req w1
+        mov ada, bob
+        .unreq bob
+        .unreq fred
+        .unreq ada
+// CHECK: mov      x5, x11                // encoding: [0xe5,0x03,0x0b,0xaa]
+// CHECK: mov      w1, w6                 // encoding: [0xe1,0x03,0x06,0x2a]
+// CHECK: mov      w1, w6                 // encoding: [0xe1,0x03,0x06,0x2a]
+
+        bob     .req b6
+        hanah   .req h5
+        sam     .req s4
+        dora    .req d3
+        quentin .req q2
+        vesna   .req v1
+        addv bob,     v0.8b
+        mov  hanah,   v4.h[3]
+        fadd s0,      sam,     sam
+        fmov d2,      dora
+        ldr  quentin, [sp]
+        mov  v0.8b,   vesna.8b
+// CHECK: addv    b6, v0.8b               // encoding: [0x06,0xb8,0x31,0x0e]
+// CHECK: mov     h5, v4.h[3]             // encoding: [0x85,0x04,0x0e,0x5e]
+// CHECK: fadd    s0, s4, s4              // encoding: [0x80,0x28,0x24,0x1e]
+// CHECK: fmov    d2, d3                  // encoding: [0x62,0x40,0x60,0x1e]
+// CHECK: ldr      q2, [sp]               // encoding: [0xe2,0x03,0xc0,0x3d]
+// CHECK: mov             v0.8b, v1.8b    // encoding: [0x20,0x1c,0xa1,0x0e]