[llvm-commits] [llvm] r45403 - in /llvm/trunk/lib/Transforms/Scalar: InstructionCombining.cpp SCCP.cpp

[Christopher Lamb]

Author: clamb
Date: Sat Dec 29 01:56:53 2007
New Revision: 45403

URL: http://llvm.org/viewvc/llvm-project?rev=45403&view=rev
Log:
Disable null pointer folding transforms for non-generic address spaces. This 
should probably be a target-specific predicate based on address space. That way 
for targets where this isn't applicable the predicate can be optimized away.

Modified:
    llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
    llvm/trunk/lib/Transforms/Scalar/SCCP.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: 
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=45403&r1=45402&r2=45403&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Sat Dec 29 
01:56:53 2007
@@ -9338,8 +9338,11 @@
         return ReplaceInstUsesWith(LI, LIB);
   }
 
-  if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
-    if (isa<ConstantPointerNull>(GEPI->getOperand(0))) {
+  if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
+    const Value *GEPI0 = GEPI->getOperand(0);
+    // TODO: Consider a target hook for valid address spaces for this xform.
+    if (isa<ConstantPointerNull>(GEPI0) &&
+        cast<PointerType>(GEPI0->getType())->getAddressSpace() == 0) {
       // Insert a new store to null instruction before the load to indicate
       // that this code is not reachable.  We do this instead of inserting
       // an unreachable instruction directly because we cannot modify the
@@ -9348,10 +9351,13 @@
                     Constant::getNullValue(Op->getType()), &LI);
       return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
     }
+  } 
 
   if (Constant *C = dyn_cast<Constant>(Op)) {
     // load null/undef -> undef
-    if ((C->isNullValue() || isa<UndefValue>(C))) {
+    // TODO: Consider a target hook for valid address spaces for this xform.
+    if (isa<UndefValue>(C) || (C->isNullValue() && 
+        cast<PointerType>(Op->getType())->getAddressSpace() == 0)) {
       // Insert a new store to null instruction before the load to indicate 
that
       // this code is not reachable.  We do this instead of inserting an
       // unreachable instruction directly because we cannot modify the CFG.

Modified: llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
URL: 
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SCCP.cpp?rev=45403&r1=45402&r2=45403&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SCCP.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SCCP.cpp Sat Dec 29 01:56:53 2007
@@ -1015,7 +1015,9 @@
   if (PtrVal.isUndefined()) return;   // The pointer is not resolved yet!
   if (PtrVal.isConstant() && !I.isVolatile()) {
     Value *Ptr = PtrVal.getConstant();
-    if (isa<ConstantPointerNull>(Ptr)) {
+    // TODO: Consider a target hook for valid address spaces for this xform.
+    if (isa<ConstantPointerNull>(Ptr) && 
+        cast<PointerType>(Ptr->getType())->getAddressSpace() == 0) {
       // load null -> null
       markConstant(IV, &I, Constant::getNullValue(I.getType()));
       return;


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