[llvm-commits] [llvm] r48192 - in /llvm/trunk: lib/Target/X86/X86ISelDAGToDAG.cpp test/CodeGen/X86/2007-07-25-EpilogueBug.ll

[Chris Lattner]

Author: lattner
Date: Mon Mar 10 18:34:12 2008
New Revision: 48192

URL: http://llvm.org/viewvc/llvm-project?rev=48192&view=rev
Log:
Don't emit FP_REG_KILL into a block that just returns.  Nothing
can be live out of the block anyway, so it isn't needed.

Modified:
    llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp
    llvm/trunk/test/CodeGen/X86/2007-07-25-EpilogueBug.ll

Modified: llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp?rev=48192&r1=48191&r2=48192&view=diff

==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelDAGToDAG.cpp Mon Mar 10 18:34:12 2008
@@ -550,7 +550,8 @@
 
   DAG.RemoveDeadNodes();
 
-  // Emit machine code to BB. 
+  // Emit machine code to BB.  This can change 'BB' to the last block being 
+  // inserted into.
   ScheduleAndEmitDAG(DAG);
   
   // If we are emitting FP stack code, scan the basic block to determine if this
@@ -566,15 +567,27 @@
   // Scan all of the machine instructions in these MBBs, checking for FP
   // stores.  (RFP32 and RFP64 will not exist in SSE mode, but RFP80 might.)
   MachineFunction::iterator MBBI = FirstMBB;
-  do {
+  MachineFunction::iterator EndMBB = BB; ++EndMBB;
+  for (; MBBI != EndMBB; ++MBBI) {
+    MachineBasicBlock *MBB = MBBI;
+    
+    // If this block returns, ignore it.  We don't want to insert an FP_REG_KILL
+    // before the return.
+    if (!MBB->empty()) {
+      MachineBasicBlock::iterator EndI = MBB->end();
+      --EndI;
+      if (EndI->getDesc().isReturn())
+        continue;
+    }
+    
     bool ContainsFPCode = false;
-    for (MachineBasicBlock::iterator I = MBBI->begin(), E = MBBI->end();
+    for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
          !ContainsFPCode && I != E; ++I) {
       if (I->getNumOperands() != 0 && I->getOperand(0).isRegister()) {
         const TargetRegisterClass *clas;
         for (unsigned op = 0, e = I->getNumOperands(); op != e; ++op) {
           if (I->getOperand(op).isRegister() && I->getOperand(op).isDef() &&
-              TargetRegisterInfo::isVirtualRegister(I->getOperand(op).getReg()) &&
+            TargetRegisterInfo::isVirtualRegister(I->getOperand(op).getReg()) &&
               ((clas = RegInfo->getRegClass(I->getOperand(0).getReg())) == 
                  X86::RFP32RegisterClass ||
                clas == X86::RFP64RegisterClass ||
@@ -608,11 +621,11 @@
     }
     // Finally, if we found any FP code, emit the FP_REG_KILL instruction.
     if (ContainsFPCode) {
-      BuildMI(*MBBI, MBBI->getFirstTerminator(),
+      BuildMI(*MBB, MBBI->getFirstTerminator(),
               TM.getInstrInfo()->get(X86::FP_REG_KILL));
       ++NumFPKill;
     }
-  } while (&*(MBBI++) != BB);
+  }
 }
 
 /// EmitSpecialCodeForMain - Emit any code that needs to be executed only in

Modified: llvm/trunk/test/CodeGen/X86/2007-07-25-EpilogueBug.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/2007-07-25-EpilogueBug.ll?rev=48192&r1=48191&r2=48192&view=diff

==============================================================================
--- llvm/trunk/test/CodeGen/X86/2007-07-25-EpilogueBug.ll (original)
+++ llvm/trunk/test/CodeGen/X86/2007-07-25-EpilogueBug.ll Mon Mar 10 18:34:12 2008
@@ -1,5 +1,7 @@
+; Verify that the addl comes before any popl.
+
 ; RUN: llvm-as < %s | llc -mtriple=i686-pc-linux-gnu -mcpu=i386 | \
-; RUN:   %prcontext ret 1 | grep FP_REG_KILL
+; RUN:   %prcontext ret 1 | grep popl
 ; PR1573
 
 	%struct.c34006f__TsB = type { i8, i32, i32, %struct.c34006f__TsB___b___XVN }