Add support for the %H output modifier.

Patch by Weiming Zhao.

llvm-svn: 161768

llvm/lib/Target/ARM/ARMAsmPrinter.cpp

@@ -529,10 +529,23 @@ bool ARMAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
       return false;
     }
 
-    // These modifiers are not yet supported.
+    // This modifier is not yet supported.
     case 'h': // A range of VFP/NEON registers suitable for VLD1/VST1.
-    case 'H': // The highest-numbered register of a pair.
       return true;
+    case 'H': // The highest-numbered register of a pair.
+      const MachineOperand &MO = MI->getOperand(OpNum);
+      if (!MO.isReg())
+        return true;
+      const TargetRegisterClass &RC = ARM::GPRRegClass;
+      const MachineFunction &MF = *MI->getParent()->getParent();
+      const TargetRegisterInfo *TRI = MF.getTarget().getRegisterInfo();
+
+      unsigned RegIdx = TRI->getEncodingValue(MO.getReg());
+      RegIdx |= 1; //The odd register is also the higher-numbered one of a pair.
+
+      unsigned Reg = RC.getRegister(RegIdx);
+      O << ARMInstPrinter::getRegisterName(Reg);
+      return false;
     }
   }
 

llvm/test/CodeGen/ARM/arm-modifier.ll

@@ -57,3 +57,12 @@ store i64 %0, i64* @f3_var, align 4
 store i64 %1, i64* @f3_var, align 4
 ret void
 }
+
+define i64 @f4(i64* %val) nounwind {
+entry:
+  ;CHECK: f4
+  ;CHECK: ldrexd [[REG1:(r[0-9]?[02468])]], {{r[0-9]?[13579]}}, [r0]
+  ;CHECK: mov r0, [[REG1]]
+  %0 = tail call i64 asm sideeffect "ldrexd $0, ${0:H}, [$1]", "=&r,r,*Qo"(i64* %val, i64* %val) nounwind
+  ret i64 %0
+}