[llvm-commits] CVS: llvm/lib/CodeGen/RegAllocSimple.cpp

[Misha Brukman]

Changes in directory llvm/lib/CodeGen:

RegAllocSimple.cpp updated: 1.6 -> 1.7

---
Log message:

Start allocating stack space at [ebp-4] to not overwrite the return address.
Also make all loads & stores 4-byte aligned for performance. ;)


---
Diffs of the changes:

Index: llvm/lib/CodeGen/RegAllocSimple.cpp
diff -u llvm/lib/CodeGen/RegAllocSimple.cpp:1.6 llvm/lib/CodeGen/RegAllocSimple.cpp:1.7
--- llvm/lib/CodeGen/RegAllocSimple.cpp:1.6	Thu Dec 12 17:20:31 2002
+++ llvm/lib/CodeGen/RegAllocSimple.cpp	Thu Dec 12 22:34:02 2002
@@ -50,13 +50,15 @@
 
     RegAllocSimple(TargetMachine &tm) : TM(tm), CurrMBB(0), maxOffset(0), 
                                         RegInfo(tm.getRegisterInfo()),
-                                        NumBytesAllocated(0), ByteAlignment(4)
+                                        ByteAlignment(4)
     {
       // build reverse mapping for physReg -> register class
       RegInfo->buildReg2RegClassMap(PhysReg2RegClassMap);
 
       RegsUsed[RegInfo->getFramePointer()] = 1;
       RegsUsed[RegInfo->getStackPointer()] = 1;
+
+      cleanupAfterFunction();
     }
 
     bool isAvailableReg(unsigned Reg) {
@@ -80,7 +82,7 @@
     void cleanupAfterFunction() {
       RegMap.clear();
       SSA2PhysRegMap.clear();
-      NumBytesAllocated = 0;
+      NumBytesAllocated = 4;
     }
 
     /// Moves value from memory into that register
@@ -112,6 +114,7 @@
                                             const TargetRegisterClass *regClass)
 {
   if (RegMap.find(VirtReg) == RegMap.end()) {
+#if 0
     unsigned size = regClass->getDataSize();
     unsigned over = NumBytesAllocated - (NumBytesAllocated % ByteAlignment);
     if (size >= ByteAlignment - over) {
@@ -120,6 +123,10 @@
     }
     RegMap[VirtReg] = NumBytesAllocated;
     NumBytesAllocated += size;
+#endif
+    // FIXME: forcing each arg to take 4 bytes on the stack
+    RegMap[VirtReg] = NumBytesAllocated;
+    NumBytesAllocated += 4;
   }
   return RegMap[VirtReg];
 }