fix header

add comments
untabify

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30486 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMMul.cpp b/lib/Target/ARM/ARMMul.cpp
index b984e7dc5c553499545d02d96564227a2f02118a..185fb96783d7dbf06d120d8514b3bbd70d727e6c 100644 (file)
--- a/lib/Target/ARM/ARMMul.cpp
+++ b/lib/Target/ARM/ARMMul.cpp
@@ -1,4 +1,4 @@
-//===-- ARMTargetMachine.cpp - Define TargetMachine for ARM ---------------===//
+//===-- ARMMul.cpp - Define TargetMachine for A5CRM -----------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -8,6 +8,7 @@
 //
 //===----------------------------------------------------------------------===//
 //
+// Modify the ARM multiplication instructions so that Rd and Rm are distinct
 //
 //===----------------------------------------------------------------------===//
 
@@ -39,25 +40,27 @@ bool FixMul::runOnMachineFunction(MachineFunction &MF) {
       MachineInstr *MI = I;
 
       if (MI->getOpcode() == ARM::MUL) {
-       MachineOperand &RdOp = MI->getOperand(0);
-       MachineOperand &RmOp = MI->getOperand(1);
-       MachineOperand &RsOp = MI->getOperand(2);
+        MachineOperand &RdOp = MI->getOperand(0);
+        MachineOperand &RmOp = MI->getOperand(1);
+        MachineOperand &RsOp = MI->getOperand(2);
 
-       unsigned Rd = RdOp.getReg();
-       unsigned Rm = RmOp.getReg();
-       unsigned Rs = RsOp.getReg();
+        unsigned Rd = RdOp.getReg();
+        unsigned Rm = RmOp.getReg();
+        unsigned Rs = RsOp.getReg();
 
-       if(Rd == Rm) {
-         Changed = true;
-         if (Rd != Rs) {
-           RmOp.setReg(Rs);
-           RsOp.setReg(Rm);
-         } else {
-           BuildMI(MBB, I, ARM::MOV, 3, ARM::R12).addReg(Rm).addImm(0)
-             .addImm(ARMShift::LSL);
-           RmOp.setReg(ARM::R12);
-         }
-       }
+        if(Rd == Rm) {
+          Changed = true;
+          if (Rd != Rs) {
+           //Rd and Rm must be distinct, but Rd can be equal to Rs.
+           //Swap Rs and Rm
+            RmOp.setReg(Rs);
+            RsOp.setReg(Rm);
+          } else {
+            BuildMI(MBB, I, ARM::MOV, 3, ARM::R12).addReg(Rm).addImm(0)
+              .addImm(ARMShift::LSL);
+            RmOp.setReg(ARM::R12);
+          }
+        }
       }
     }
   }