ARM: diagnose ARM/Thumb assembly switches on CPUs only supporting one.

Some ARM CPUs only support ARM mode (ancient v4 ones, for example) and some
only support Thumb mode (M-class ones currently). This makes sure such CPUs
default to the correct mode and makes the AsmParser diagnose an attempt to
switch modes incorrectly.

rdar://14024354

llvm-svn: 183710

1 files changed, 19 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index ce935b9817c..314d37d7d58 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -152,12 +152,19 @@ class ARMAsmParser : public MCTargetAsmParser {
   bool isThumbTwo() const {
     return isThumb() && (STI.getFeatureBits() & ARM::FeatureThumb2);
   }
+  bool hasThumb() const {
+    return STI.getFeatureBits() & ARM::HasV4TOps;
+  }
   bool hasV6Ops() const {
     return STI.getFeatureBits() & ARM::HasV6Ops;
   }
   bool hasV7Ops() const {
     return STI.getFeatureBits() & ARM::HasV7Ops;
   }
+  bool hasARM() const {
+    return !(STI.getFeatureBits() & ARM::FeatureNoARM);
+  }
+
   void SwitchMode() {
     unsigned FB = ComputeAvailableFeatures(STI.ToggleFeature(ARM::ModeThumb));
     setAvailableFeatures(FB);
@@ -7816,6 +7823,9 @@ bool ARMAsmParser::parseDirectiveThumb(SMLoc L) {
     return Error(L, "unexpected token in directive");
   Parser.Lex();
 
+  if (!hasThumb())
+    return Error(L, "target does not support Thumb mode");
+
   if (!isThumb())
     SwitchMode();
   getParser().getStreamer().EmitAssemblerFlag(MCAF_Code16);
@@ -7829,6 +7839,9 @@ bool ARMAsmParser::parseDirectiveARM(SMLoc L) {
     return Error(L, "unexpected token in directive");
   Parser.Lex();
 
+  if (!hasARM())
+    return Error(L, "target does not support ARM mode");
+
   if (isThumb())
     SwitchMode();
   getParser().getStreamer().EmitAssemblerFlag(MCAF_Code32);
@@ -7918,10 +7931,16 @@ bool ARMAsmParser::parseDirectiveCode(SMLoc L) {
   Parser.Lex();
 
   if (Val == 16) {
+    if (!hasThumb())
+      return Error(L, "target does not support Thumb mode");
+
     if (!isThumb())
       SwitchMode();
     getParser().getStreamer().EmitAssemblerFlag(MCAF_Code16);
   } else {
+    if (!hasARM())
+      return Error(L, "target does not support ARM mode");
+
     if (isThumb())
       SwitchMode();
     getParser().getStreamer().EmitAssemblerFlag(MCAF_Code32);