2 files changed, 37 insertions, 25 deletions

diff --git a/llvm/lib/Target/ARM/ARMLoadStoreOptimizer.cpp b/llvm/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
index f9eec7d4006..3afadab6c17 100644
--- a/llvm/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
+++ b/llvm/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
@@ -2161,33 +2161,39 @@ bool ARMPreAllocLoadStoreOpt::RescheduleOps(MachineBasicBlock *MBB,
     unsigned LastBytes = 0;
     unsigned NumMove = 0;
     for (int i = Ops.size() - 1; i >= 0; --i) {
+      // Make sure each operation has the same kind.
       MachineInstr *Op = Ops[i];
-      unsigned Loc = MI2LocMap[Op];
-      if (Loc <= FirstLoc) {
-        FirstLoc = Loc;
-        FirstOp = Op;
-      }
-      if (Loc >= LastLoc) {
-        LastLoc = Loc;
-        LastOp = Op;
-      }
-
       unsigned LSMOpcode
         = getLoadStoreMultipleOpcode(Op->getOpcode(), ARM_AM::ia);
       if (LastOpcode && LSMOpcode != LastOpcode)
         break;
 
+      // Check that we have a continuous set of offsets.
       int Offset = getMemoryOpOffset(*Op);
       unsigned Bytes = getLSMultipleTransferSize(Op);
       if (LastBytes) {
         if (Bytes != LastBytes || Offset != (LastOffset + (int)Bytes))
           break;
       }
+
+      // Don't try to reschedule too many instructions.
+      if (++NumMove == 8) // FIXME: Tune this limit.
+        break;
+
+      // Found a mergable instruction; save information about it.
       LastOffset = Offset;
       LastBytes = Bytes;
       LastOpcode = LSMOpcode;
-      if (++NumMove == 8) // FIXME: Tune this limit.
-        break;
+
+      unsigned Loc = MI2LocMap[Op];
+      if (Loc <= FirstLoc) {
+        FirstLoc = Loc;
+        FirstOp = Op;
+      }
+      if (Loc >= LastLoc) {
+        LastLoc = Loc;
+        LastOp = Op;
+      }
     }
 
     if (NumMove <= 1)
diff --git a/llvm/test/CodeGen/ARM/prera-ldst-insertpt.mir b/llvm/test/CodeGen/ARM/prera-ldst-insertpt.mir
index 1db38c8b004..eafcc7c36d3 100644
--- a/llvm/test/CodeGen/ARM/prera-ldst-insertpt.mir
+++ b/llvm/test/CodeGen/ARM/prera-ldst-insertpt.mir
@@ -36,6 +36,14 @@ body:             |
     t2STRi12 %1, %0, 0, 14, _ :: (store 4)
     %10 : rgpr = t2LSLri %2, 1, 14, _, _
     t2STRi12 killed %10, %0, 4, 14, _ :: (store 4)
+
+    ; Make sure we move the paired stores next to each other, and
+    ; insert them in an appropriate location.
+    ; CHECK: t2STRi12 %1,
+    ; CHECK-NEXT: t2STRi12 killed %10,
+    ; CHECK-NEXT: t2MOVi
+    ; CHECK-NEXT: t2ADDrs
+
     %11 : rgpr = t2MOVi 55, 14, _, _
     %12 : gprnopc = t2ADDrs %11, killed %7, 19, 14, _, _
     t2STRi12 killed %12, %0, 16, 14, _ :: (store 4)
@@ -43,12 +51,7 @@ body:             |
     t2STRi12 killed %13, %0, 20, 14, _ :: (store 4)
 
     ; Make sure we move the paired stores next to each other.
-    ; FIXME: Make sure we don't extend the live-range of a store
-    ; when we don't need to.
-    ; CHECK: t2STRi12 %1,
-    ; CHECK-NEXT: t2STRi12 killed %10,
-    ; CHECK-NEXT: %13 = t2ADDrs %11
-    ; CHECK-NEXT: t2STRi12 killed %12,
+    ; CHECK: t2STRi12 killed %12,
     ; CHECK-NEXT: t2STRi12 killed %13,
 
     tBX_RET 14, _
@@ -73,6 +76,15 @@ body:             |
     t2STRi12 killed %10, %0, 4, 14, _ :: (store 4)
     %3 : rgpr = t2MUL %2, %2, 14, _
     t2STRi12 %3, %0, 8, 14, _ :: (store 4)
+
+    ; Make sure we move the paired stores next to each other, and
+    ; insert them in an appropriate location.
+    ; CHECK: t2STRi12 {{.*}}, 0
+    ; CHECK-NEXT: t2STRi12 {{.*}}, 4
+    ; CHECK-NEXT: t2STRi12 {{.*}}, 8
+    ; CHECK-NEXT: t2MUL
+    ; CHECK-NEXT: t2MOVi32imm
+
     %4 : rgpr = t2MUL %1, %1, 14, _
     %5 : rgpr = t2MOVi32imm -858993459
     %6 : rgpr, %7 : rgpr  = t2UMULL killed %3, %5, 14, _
@@ -85,13 +97,7 @@ body:             |
     t2STRi12 killed %13, %0, 20, 14, _ :: (store 4)
 
     ; Make sure we move the paired stores next to each other.
-    ; FIXME: Make sure we don't extend the live-range of a store
-    ; when we don't need to.
-    ; CHECK: t2STRi12 {{.*}}, 0
-    ; CHECK-NEXT: t2STRi12 {{.*}}, 4
-    ; CHECK-NEXT: t2STRi12 {{.*}}, 8
-    ; CHECK-NEXT: t2ADDrs
-    ; CHECK-NEXT: t2STRi12 {{.*}}, 16
+    ; CHECK: t2STRi12 {{.*}}, 16
     ; CHECK-NEXT: t2STRi12 {{.*}}, 20
 
     tBX_RET 14, _