ARM IAS: (partially) support .arch_extension directive

This adds a partial implementation of the .arch_extension directive to the
integrated ARM assembler.  There are a number of limitations to this
implementation arising from the target backend support rather than the
implementation itself.  Namely, iWMMXT (v1 and v2), Maverick, and XScale support
is not present in the ARM backend.  Currently, there is no check for A-class
only (needed for virt), and no ARMv6k detection (needed for os and sec).  The
remainder of the extensions are fully supported.

llvm-svn: 201471

1 files changed, 82 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index d3df3dc316a..e2df2ab16c0 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -227,6 +227,7 @@ class ARMAsmParser : public MCTargetAsmParser {
   bool parseDirectiveTLSDescSeq(SMLoc L);
   bool parseDirectiveMovSP(SMLoc L);
   bool parseDirectiveObjectArch(SMLoc L);
+  bool parseDirectiveArchExtension(SMLoc L);
 
   StringRef splitMnemonic(StringRef Mnemonic, unsigned &PredicationCode,
                           bool &CarrySetting, unsigned &ProcessorIMod,
@@ -8016,6 +8017,8 @@ bool ARMAsmParser::ParseDirective(AsmToken DirectiveID) {
     return parseDirectiveMovSP(DirectiveID.getLoc());
   else if (IDVal == ".object_arch")
     return parseDirectiveObjectArch(DirectiveID.getLoc());
+  else if (IDVal == ".arch_extension")
+    return parseDirectiveArchExtension(DirectiveID.getLoc());
   return true;
 }
 
@@ -9064,6 +9067,85 @@ extern "C" void LLVMInitializeARMAsmParser() {
 #define GET_MATCHER_IMPLEMENTATION
 #include "ARMGenAsmMatcher.inc"
 
+static const struct ExtMapEntry {
+  const char *Extension;
+  const unsigned ArchCheck;
+  const uint64_t Features;
+} Extensions[] = {
+  { "crc", Feature_HasV8, ARM::FeatureCRC },
+  { "crypto",  Feature_HasV8,
+    ARM::FeatureCrypto | ARM::FeatureNEON | ARM::FeatureFPARMv8 },
+  { "fp", Feature_HasV8, ARM::FeatureFPARMv8 },
+  { "idiv", Feature_HasV7 | Feature_IsNotMClass,
+    ARM::FeatureHWDiv | ARM::FeatureHWDivARM },
+  // FIXME: iWMMXT not supported
+  { "iwmmxt", Feature_None, 0 },
+  // FIXME: iWMMXT2 not supported
+  { "iwmmxt2", Feature_None, 0 },
+  // FIXME: Maverick not supported
+  { "maverick", Feature_None, 0 },
+  { "mp", Feature_HasV7 | Feature_IsNotMClass, ARM::FeatureMP },
+  // FIXME: ARMv6-m OS Extensions feature not checked
+  { "os", Feature_None, 0 },
+  // FIXME: Also available in ARMv6-K
+  { "sec", Feature_HasV7, ARM::FeatureTrustZone },
+  { "simd", Feature_HasV8, ARM::FeatureNEON | ARM::FeatureFPARMv8 },
+  // FIXME: Only available in A-class, isel not predicated
+  { "virt", Feature_HasV7, ARM::FeatureVirtualization },
+  // FIXME: xscale not supported
+  { "xscale", Feature_None, 0 },
+};
+
+template <typename T, size_t N>
+size_t countof(const T (&)[N]) { return N; }
+
+/// parseDirectiveArchExtension
+///   ::= .arch_extension [no]feature
+bool ARMAsmParser::parseDirectiveArchExtension(SMLoc L) {
+  if (getLexer().isNot(AsmToken::Identifier)) {
+    Error(getLexer().getLoc(), "unexpected token");
+    Parser.eatToEndOfStatement();
+    return false;
+  }
+
+  StringRef Extension = Parser.getTok().getString();
+  SMLoc ExtLoc = Parser.getTok().getLoc();
+  getLexer().Lex();
+
+  bool EnableFeature = true;
+  if (!Extension.lower().compare(0, 2, "no")) {
+    EnableFeature = false;
+    Extension = Extension.substr(2);
+  }
+
+  for (unsigned EI = 0, EE = countof(Extensions); EI != EE; ++EI) {
+    if (Extensions[EI].Extension != Extension)
+      continue;
+
+    unsigned FB = getAvailableFeatures();
+    if ((FB & Extensions[EI].ArchCheck) != Extensions[EI].ArchCheck) {
+      Error(ExtLoc, "architectural extension '" + Extension + "' is not "
+            "allowed for the current base architecture");
+      return false;
+    }
+
+    if (!Extensions[EI].Features)
+      report_fatal_error("unsupported architectural extension: " + Extension);
+
+    if (EnableFeature)
+      FB |= ComputeAvailableFeatures(Extensions[EI].Features);
+    else
+      FB &= ~ComputeAvailableFeatures(Extensions[EI].Features);
+
+    setAvailableFeatures(FB);
+    return false;
+  }
+
+  Error(ExtLoc, "unknown architectural extension: " + Extension);
+  Parser.eatToEndOfStatement();
+  return false;
+}
+
 // Define this matcher function after the auto-generated include so we
 // have the match class enum definitions.
 unsigned ARMAsmParser::validateTargetOperandClass(MCParsedAsmOperand *AsmOp,