Change the arm assembler to support this from the v7c spec:

"When assembling to the ARM instruction set, the .N qualifier produces
an assembler error and the .W qualifier has no effect."

In the pre-matcher handler in the asm parser the ".w" (wide) qualifier 
when in ARM mode is now discarded. And an error message is now
produced when the ".n" (narrow) qualifier is used in ARM mode.

Test cases for these were added.

rdar://14064574

llvm-svn: 184224

3 files changed, 16 insertions, 1 deletions

diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 170d4347445..647fdb396d7 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -5266,7 +5266,17 @@ bool ARMAsmParser::ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
         doesIgnoreDataTypeSuffix(Mnemonic, ExtraToken))
       continue;
 
-    if (ExtraToken != ".n") {
+    // For for ARM mode generate an error if the .n qualifier is used.
+    if (ExtraToken == ".n" && !isThumb()) {
+      SMLoc Loc = SMLoc::getFromPointer(NameLoc.getPointer() + Start);
+      return Error(Loc, "instruction with .n (narrow) qualifier not allowed in "
+                   "arm mode");
+    }
+
+    // The .n qualifier is always discarded as that is what the tables
+    // and matcher expect.  In ARM mode the .w qualifier has no effect,
+    // so discard it to avoid errors that can be caused by the matcher.
+    if (ExtraToken != ".n" && (isThumb() || ExtraToken != ".w")) {
       SMLoc Loc = SMLoc::getFromPointer(NameLoc.getPointer() + Start);
       Operands.push_back(ARMOperand::CreateToken(ExtraToken, Loc));
     }
diff --git a/llvm/test/MC/ARM/basic-arm-instructions.s b/llvm/test/MC/ARM/basic-arm-instructions.s
index 8aec4b3e603..8335797bc66 100644
--- a/llvm/test/MC/ARM/basic-arm-instructions.s
+++ b/llvm/test/MC/ARM/basic-arm-instructions.s
@@ -1247,9 +1247,11 @@ Lforward:
 @ NOP
 @------------------------------------------------------------------------------
         nop
+        nop.w
         nopgt
 
 @ CHECK: nop @ encoding: [0x00,0xf0,0x20,0xe3]
+@ CHECK: nop @ encoding: [0x00,0xf0,0x20,0xe3]
 @ CHECK: nopgt @ encoding: [0x00,0xf0,0x20,0xc3]
 
 
diff --git a/llvm/test/MC/ARM/diagnostics.s b/llvm/test/MC/ARM/diagnostics.s
index b4b73862de4..82d6ae34655 100644
--- a/llvm/test/MC/ARM/diagnostics.s
+++ b/llvm/test/MC/ARM/diagnostics.s
@@ -376,3 +376,6 @@
         isb #16
 @ CHECK-ERRORS: error: immediate value out of range
 @ CHECK-ERRORS: error: immediate value out of range
+
+        nop.n
+@ CHECK-ERRORS: error: instruction with .n (narrow) qualifier not allowed in arm mode