[mips] Enable the mnemonic spell corrector

This implements suggesting alternative mnemonics when an invalid one is
specified. For example `addru $9, $6, 17767` leads to the following
error message:

error: unknown instruction, did you mean: add, addiu, addu, maddu?

Differential revision: https://reviews.llvm.org/D40646

llvm-svn: 342119

2 files changed, 72 insertions, 1 deletions

diff --git a/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp b/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
index ce7db657f5e..ae70fdd37c1 100644
--- a/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
+++ b/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
@@ -6371,6 +6371,9 @@ bool MipsAsmParser::parseBracketSuffix(StringRef Name,
   return false;
 }
 
+static std::string MipsMnemonicSpellCheck(StringRef S, uint64_t FBS,
+                                          unsigned VariantID = 0);
+
 bool MipsAsmParser::ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
                                      SMLoc NameLoc, OperandVector &Operands) {
   MCAsmParser &Parser = getParser();
@@ -6381,7 +6384,9 @@ bool MipsAsmParser::ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
 
   // Check if we have valid mnemonic
   if (!mnemonicIsValid(Name, 0)) {
-    return Error(NameLoc, "unknown instruction");
+    uint64_t FBS = ComputeAvailableFeatures(getSTI().getFeatureBits());
+    std::string Suggestion = MipsMnemonicSpellCheck(Name, FBS);
+    return Error(NameLoc, "unknown instruction" + Suggestion);
   }
   // First operand in MCInst is instruction mnemonic.
   Operands.push_back(MipsOperand::CreateToken(Name, NameLoc, *this));
@@ -8257,6 +8262,7 @@ extern "C" void LLVMInitializeMipsAsmParser() {
 
 #define GET_REGISTER_MATCHER
 #define GET_MATCHER_IMPLEMENTATION
+#define GET_MNEMONIC_SPELL_CHECKER
 #include "MipsGenAsmMatcher.inc"
 
 bool MipsAsmParser::mnemonicIsValid(StringRef Mnemonic, unsigned VariantID) {
diff --git a/llvm/test/MC/Mips/invalid-instructions-spellcheck.s b/llvm/test/MC/Mips/invalid-instructions-spellcheck.s
new file mode 100644
index 00000000000..c242fd05b7a
--- /dev/null
+++ b/llvm/test/MC/Mips/invalid-instructions-spellcheck.s
@@ -0,0 +1,65 @@
+# RUN: not llvm-mc -arch mips -mcpu=mips32r2 -mattr=+micromips %s 2>&1 \
+# RUN:   | FileCheck --check-prefixes=ALL,MMR2 %s
+# RUN: not llvm-mc -arch mips -mcpu=mips32r6 -mattr=+micromips %s 2>&1 \
+# RUN:   | FileCheck --check-prefixes=ALL,MMR6 %s
+# RUN: not llvm-mc -arch mips -mcpu=mips32r6 %s 2>&1 \
+# RUN:   | FileCheck --check-prefixes=ALL,MIPS32R6 %s
+
+# This tests the mnemonic spell checker.
+
+# First check what happens when an instruction is omitted:
+
+$2, $1, $25
+
+# ALL:      error: unexpected token at start of statement
+# ALL-NEXT: $2, $1, $25
+# ALL-NEXT:  ^
+
+# We don't want to see a suggestion here; the edit distance is too large to
+# give sensible suggestions:
+
+aaaaaaaaaaaaaaa $2, $1, $25
+
+# ALL:      error: unknown instruction
+# ALL-NEXT: aaaaaaaaaaaaaaa $2, $1, $25
+# ALL-NEXT: ^
+
+# Check that we get one suggestion: 'addiuspi' is 1 edit away, i.e. an deletion.
+
+addiuspi -16
+
+# MMR2:     error: unknown instruction, did you mean: addiusp?
+# MMR6:     error: unknown instruction, did you mean: addiusp?
+# MIPS32R6: error: unknown instruction{{$}}
+# ALL:      addiuspi -16
+# ALL-NEXT: ^
+
+# Check edit distance 1 and 2, just insertions:
+
+addru $9, $6, 17767
+
+# MMR2:      error: unknown instruction, did you mean: add, addiu, addu, maddu?
+# MMR6:      error: unknown instruction, did you mean: add, addiu, addu?
+# MIPS32R6:  error: unknown instruction, did you mean: add, addiu, addu?
+# ALL:       addru $9, $6, 17767
+# ALL-NEXT:  ^
+
+# Check an instruction that is 2 edits away, and also has a lot of candidates:
+
+culE.d  $fcc7, $f24, $f18
+
+# MMR2:     error: unknown instruction, did you mean: c.le.d, c.ule.d?
+# MMR6:     error: unknown instruction{{$}}
+# MIPS32R6: error: unknown instruction{{$}}
+# ALL:      culE.d  $fcc7, $f24, $f18
+# ALL-NEXT: ^
+
+# Check that candidates list includes only instructions valid for target CPU.
+
+swk $3, $4
+
+# MMR2: error: unknown instruction, did you mean: sw, swl, swm, swp, swr, usw?
+# MMR6: error: unknown instruction, did you mean: sw, swm, swp, usw?
+# MIPS32R6: error: unknown instruction, did you mean: sw, usw?
+# ALL:      swk $3, $4
+# ALL-NEXT: ^