[llvm-commits] [llvm] r110947 - /llvm/trunk/lib/Target/ARM/ARMConstantIslandPass.cpp

[Evan Cheng]

Author: evancheng
Date: Thu Aug 12 15:30:05 2010
New Revision: 110947

URL: http://llvm.org/viewvc/llvm-project?rev=110947&view=rev
Log:
Make sure ARM constant island pass does not break up an IT block. If the split point is in the middle of an IT block, it should move it up to just above the IT instruction. rdar://8302637

Modified:
    llvm/trunk/lib/Target/ARM/ARMConstantIslandPass.cpp

Modified: llvm/trunk/lib/Target/ARM/ARMConstantIslandPass.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMConstantIslandPass.cpp?rev=110947&r1=110946&r2=110947&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMConstantIslandPass.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMConstantIslandPass.cpp Thu Aug 12 15:30:05 2010
@@ -18,6 +18,7 @@
 #include "ARMAddressingModes.h"
 #include "ARMMachineFunctionInfo.h"
 #include "ARMInstrInfo.h"
+#include "Thumb2InstrInfo.h"
 #include "llvm/CodeGen/MachineConstantPool.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
@@ -1181,11 +1182,13 @@
     MachineBasicBlock::iterator MI = UserMI;
     ++MI;
     unsigned CPUIndex = CPUserIndex+1;
+    unsigned NumCPUsers = CPUsers.size();
+    MachineInstr *LastIT = 0;
     for (unsigned Offset = UserOffset+TII->GetInstSizeInBytes(UserMI);
          Offset < BaseInsertOffset;
          Offset += TII->GetInstSizeInBytes(MI),
-            MI = llvm::next(MI)) {
-      if (CPUIndex < CPUsers.size() && CPUsers[CPUIndex].MI == MI) {
+           MI = llvm::next(MI)) {
+      if (CPUIndex < NumCPUsers && CPUsers[CPUIndex].MI == MI) {
         CPUser &U = CPUsers[CPUIndex];
         if (!OffsetIsInRange(Offset, EndInsertOffset,
                              U.MaxDisp, U.NegOk, U.IsSoImm)) {
@@ -1197,9 +1200,23 @@
         EndInsertOffset += CPUsers[CPUIndex].CPEMI->getOperand(2).getImm();
         CPUIndex++;
       }
+
+      // Remember the last IT instruction.
+      if (MI->getOpcode() == ARM::t2IT)
+        LastIT = MI;
     }
+
     DEBUG(errs() << "Split in middle of big block\n");
-    NewMBB = SplitBlockBeforeInstr(prior(MI));
+    --MI;
+
+    // Avoid splitting an IT block.
+    if (LastIT) {
+      unsigned PredReg = 0;
+      ARMCC::CondCodes CC = llvm::getITInstrPredicate(MI, PredReg);
+      if (CC != ARMCC::AL)
+        MI = LastIT;
+    }
+    NewMBB = SplitBlockBeforeInstr(MI);
   }
 }