[mips] Print warning when using register names not available in N32/64

[vkalintiris]

Summary

The register names t4-t7 are not available in the N32 and N64 ABIs.
This patch prints a warning, when those names are used in N32/64,
along with a fix-it with the correct register names.

Depends on D5270

[dsanders]

LGTM with a couple nits

include/llvm/MC/MCParser/MCAsmLexer.h

77

I'd spell this 'getLocRange()'

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

1665

We should assert that FixedName is not empty.

[vkalintiris]

Renamed getRange() to getLocRange() and added an assert for the FixedName string.

[dsanders]

Thanks. I nearly forgot about this: We need to send it to the list since it touches common code but I'll be happy to LGTM it properly once I see it there.

[vkalintiris]

Added llvm-commits because this patch now touches common code.

[dsanders]

LGTM

include/llvm/MC/MCParser/MCAsmLexer.h

AsmToken(TokenKind _Kind, StringRef _Str, int64_t _IntVal = 0)
     : Kind(_Kind), Str(_Str), IntVal(64, _IntVal, true) {}
 
   TokenKind getKind() const { return Kind; }
   bool is(TokenKind K) const { return Kind == K; }
   bool isNot(TokenKind K) const { return Kind != K; }
 
   SMLoc getLoc() const;
   SMLoc getEndLoc() const;
+  SMRange getLocRange() const;
 
   /// getStringContents - Get the contents of a string token (without quotes).
   StringRef getStringContents() const {
     assert(Kind == String && "This token isn't a string!");
     return Str.slice(1, Str.size() - 1);
   }
 
   /// getIdentifier - Get the identifier string for the current token, which

lib/MC/MCParser/MCAsmLexer.cpp

 
 SMLoc AsmToken::getLoc() const {
   return SMLoc::getFromPointer(Str.data());
 }
 
 SMLoc AsmToken::getEndLoc() const {
   return SMLoc::getFromPointer(Str.data() + Str.size());
 }
+
+SMRange AsmToken::getLocRange() const {
+  return SMRange(getLoc(), getEndLoc());
+}

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

 #include "llvm/MC/MCParser/MCParsedAsmOperand.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/MCTargetAsmParser.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/SourceMgr.h"
 #include <memory>
 
 using namespace llvm;
 
 #define DEBUG_TYPE "mips-asm-parser"
 
 namespace llvm {
 class MCInstrInfo;
class MipsAsmParser : public MCTargetAsmParser {
   MCSubtargetInfo &STI;
   MCAsmParser &Parser;
   SmallVector<std::unique_ptr<MipsAssemblerOptions>, 2> AssemblerOptions;
   MCSymbol *CurrentFn; // Pointer to the function being parsed. It may be a
                        // nullptr, which indicates that no function is currently
                        // selected. This usually happens after an '.end func'
                        // directive.
 
+  // Print a warning along with its fix-it message at the given range.
+  void printWarningWithFixIt(const Twine &Msg, const Twine &FixMsg,
+                             SMRange Range, bool ShowColors = true);
+
 #define GET_ASSEMBLER_HEADER
 #include "MipsGenAsmMatcher.inc"
 
   unsigned checkTargetMatchPredicate(MCInst &Inst) override;
 
   bool MatchAndEmitInstruction(SMLoc IDLoc, unsigned &Opcode,
                                OperandVector &Operands, MCStreamer &Out,
                                uint64_t &ErrorInfo,
if ((RegIndex != 0) &&
     if (RegIndex == 1)
       Warning(Loc, "Used $at without \".set noat\"");
     else
       Warning(Loc, Twine("Used $") + Twine(RegIndex) + " with \".set at=$" +
                        Twine(RegIndex) + "\"");
   }
 }
 
+void
+MipsAsmParser::printWarningWithFixIt(const Twine &Msg, const Twine &FixMsg,
+                                     SMRange Range, bool ShowColors) {
+  getSourceManager().PrintMessage(Range.Start, SourceMgr::DK_Warning, Msg,
+                                  { Range }, { SMFixIt(Range, FixMsg) },
+                                  ShowColors);
+}
+
 int MipsAsmParser::matchCPURegisterName(StringRef Name) {
   int CC;
 
   CC = StringSwitch<unsigned>(Name)
            .Case("zero", 0)
            .Case("at", 1)
            .Case("a0", 4)
            .Case("a1", 5)
CC = StringSwitch<unsigned>(Name)
            .Case("t7", 15)
            .Case("t8", 24)
            .Case("t9", 25)
            .Default(-1);
 
   if (!(isABI_N32() || isABI_N64()))
     return CC;
 
+  if (12 <= CC && CC <= 15) {
+    // Name is one of t4-t7
+    AsmToken RegTok = getLexer().peekTok();
+    SMRange RegRange = RegTok.getLocRange();
+
+    StringRef FixedName = StringSwitch<StringRef>(Name)
+                              .Case("t4", "t0")
+                              .Case("t5", "t1")
+                              .Case("t6", "t2")
+                              .Case("t7", "t3")
+                              .Default("");
+    assert(FixedName != "" &&  "Register name is not one of t4-t7.");
+
+    printWarningWithFixIt("register names $t4-$t7 are only available in O32.",
+                          "Did you mean $" + FixedName + "?", RegRange);
+  }
+
   // Although SGI documentation just cuts out t0-t3 for n32/n64,
   // GNU pushes the values of t0-t3 to override the o32/o64 values for t4-t7
   // We are supporting both cases, so for t0-t3 we'll just push them to t4-t7.
   if (8 <= CC && CC <= 11)
     CC += 4;
 
   if (CC == -1)
     CC = StringSwitch<unsigned>(Name)

test/MC/Mips/mips64-register-names-n32-n64.s

-# RUN: llvm-mc %s -triple=mips64-unknown-freebsd -show-encoding | FileCheck %s
+# RUN: llvm-mc %s -triple=mips64-unknown-freebsd -show-encoding 2>%t0 \
+# RUN:     | FileCheck %s
+# RUN: FileCheck -check-prefix=WARNING %s < %t0
+#
 # RUN: llvm-mc %s -triple=mips64-unknown-freebsd -show-encoding \
-# RUN:     -mattr=-n64,+n32 | FileCheck %s
-
+# RUN:     -mattr=-n64,+n32 2>%t1 | FileCheck %s
+# RUN: FileCheck -check-prefix=WARNING %s < %t1
+#
 # Check that the register names are mapped to their correct numbers for n32/n64
 # Second byte of addiu with $zero at rt contains the number of the source
 # register.
 
 .set noat
 daddiu  $zero, $zero, 0     # CHECK: encoding: [0x64,0x00,0x00,0x00]
 daddiu  $at, $zero, 0       # CHECK: encoding: [0x64,0x01,0x00,0x00]
 daddiu  $v0, $zero, 0       # CHECK: encoding: [0x64,0x02,0x00,0x00]
 daddiu  $v1, $zero, 0       # CHECK: encoding: [0x64,0x03,0x00,0x00]
 daddiu  $a0, $zero, 0       # CHECK: encoding: [0x64,0x04,0x00,0x00]
 daddiu  $a1, $zero, 0       # CHECK: encoding: [0x64,0x05,0x00,0x00]
 daddiu  $a2, $zero, 0       # CHECK: encoding: [0x64,0x06,0x00,0x00]
 daddiu  $a3, $zero, 0       # CHECK: encoding: [0x64,0x07,0x00,0x00]
 daddiu  $a4, $zero, 0       # CHECK: encoding: [0x64,0x08,0x00,0x00]
 daddiu  $a5, $zero, 0       # CHECK: encoding: [0x64,0x09,0x00,0x00]
 daddiu  $a6, $zero, 0       # CHECK: encoding: [0x64,0x0a,0x00,0x00]
 daddiu  $a7, $zero, 0       # CHECK: encoding: [0x64,0x0b,0x00,0x00]
 daddiu  $t0, $zero, 0 # [*] # CHECK: encoding: [0x64,0x0c,0x00,0x00]
 daddiu  $t1, $zero, 0 # [*] # CHECK: encoding: [0x64,0x0d,0x00,0x00]
 daddiu  $t2, $zero, 0 # [*] # CHECK: encoding: [0x64,0x0e,0x00,0x00]
 daddiu  $t3, $zero, 0 # [*] # CHECK: encoding: [0x64,0x0f,0x00,0x00]
+# WARNING: mips64-register-names-n32-n64.s:[[@LINE+4]]:9: warning: register names $t4-$t7 are only available in O32.
+# WARNING-NEXT: daddiu  $t4, $zero, 0       # {{CHECK}}: encoding: [0x64,0x0c,0x00,0x00]
+# WARNING-NEXT:          ^~
+# WARNING-NEXT:          Did you mean $t0?
 daddiu  $t4, $zero, 0       # CHECK: encoding: [0x64,0x0c,0x00,0x00]
+# WARNING: mips64-register-names-n32-n64.s:[[@LINE+4]]:9: warning: register names $t4-$t7 are only available in O32.
+# WARNING-NEXT: daddiu  $t5, $zero, 0       # {{CHECK}}: encoding: [0x64,0x0d,0x00,0x00]
+# WARNING-NEXT:          ^~
+# WARNING-NEXT:          Did you mean $t1?
 daddiu  $t5, $zero, 0       # CHECK: encoding: [0x64,0x0d,0x00,0x00]
+# WARNING: mips64-register-names-n32-n64.s:[[@LINE+4]]:9: warning: register names $t4-$t7 are only available in O32.
+# WARNING-NEXT: daddiu  $t6, $zero, 0       # {{CHECK}}: encoding: [0x64,0x0e,0x00,0x00]
+# WARNING-NEXT:          ^~
+# WARNING-NEXT:          Did you mean $t2?
 daddiu  $t6, $zero, 0       # CHECK: encoding: [0x64,0x0e,0x00,0x00]
+# WARNING: mips64-register-names-n32-n64.s:[[@LINE+4]]:9: warning: register names $t4-$t7 are only available in O32.
+# WARNING-NEXT: daddiu  $t7, $zero, 0       # {{CHECK}}: encoding: [0x64,0x0f,0x00,0x00]
+# WARNING-NEXT:          ^~
+# WARNING-NEXT:          Did you mean $t3?
 daddiu  $t7, $zero, 0       # CHECK: encoding: [0x64,0x0f,0x00,0x00]
 daddiu  $s0, $zero, 0       # CHECK: encoding: [0x64,0x10,0x00,0x00]
 daddiu  $s1, $zero, 0       # CHECK: encoding: [0x64,0x11,0x00,0x00]
 daddiu  $s2, $zero, 0       # CHECK: encoding: [0x64,0x12,0x00,0x00]
 daddiu  $s3, $zero, 0       # CHECK: encoding: [0x64,0x13,0x00,0x00]
 daddiu  $s4, $zero, 0       # CHECK: encoding: [0x64,0x14,0x00,0x00]
 daddiu  $s5, $zero, 0       # CHECK: encoding: [0x64,0x15,0x00,0x00]
 daddiu  $s6, $zero, 0       # CHECK: encoding: [0x64,0x16,0x00,0x00]