ARM assembly parsing and encoding for BLX (immediate).

Add parsing support for BLX (immediate). Since the register operand version is
predicated and the label operand version is not, we have to use some special
handling to get the operand list right for matching.

llvm-svn: 136406

2 files changed, 13 insertions, 2 deletions

diff --git a/llvm/lib/Target/ARM/ARMInstrInfo.td b/llvm/lib/Target/ARM/ARMInstrInfo.td
index fec5f72bcfe..1a23651d8d3 100644
--- a/llvm/lib/Target/ARM/ARMInstrInfo.td
+++ b/llvm/lib/Target/ARM/ARMInstrInfo.td
@@ -1639,9 +1639,9 @@ let isBranch = 1, isTerminator = 1 in {
 
 }
 
-// BLX (immediate) -- for disassembly only
+// BLX (immediate)
 def BLXi : AXI<(outs), (ins br_target:$target), BrMiscFrm, NoItinerary,
-               "blx\t$target", [/* pattern left blank */]>,
+               "blx\t$target", []>,
            Requires<[IsARM, HasV5T]> {
   let Inst{31-25} = 0b1111101;
   bits<25> target;
diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index a528572349b..42e2f7f8f54 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -2675,6 +2675,17 @@ bool ARMAsmParser::ParseInstruction(StringRef Name, SMLoc NameLoc,
     delete Op;
   }
 
+  // ARM mode 'blx' need special handling, as the register operand version
+  // is predicable, but the label operand version is not. So, we can't rely
+  // on the Mnemonic based checking to correctly figure out when to put
+  // a CondCode operand in the list. If we're trying to match the label
+  // version, remove the CondCode operand here.
+  if (!isThumb() && Mnemonic == "blx" && Operands.size() == 3 &&
+      static_cast<ARMOperand*>(Operands[2])->isImm()) {
+    ARMOperand *Op = static_cast<ARMOperand*>(Operands[1]);
+    Operands.erase(Operands.begin() + 1);
+    delete Op;
+  }
   return false;
 }