[llvm-commits] [llvm] r46351 - in /llvm/trunk: lib/Transforms/Scalar/DeadStoreElimination.cpp test/Transforms/DeadStoreElimination/byval.ll

[Owen Anderson]

Author: resistor
Date: Fri Jan 25 04:10:33 2008
New Revision: 46351

URL: http://llvm.org/viewvc/llvm-project?rev=46351&view=rev
Log:
DeadStoreElimination can treat byval parameters as if there were alloca's for the purpose of removing end-of-function stores.

Added:
    llvm/trunk/test/Transforms/DeadStoreElimination/byval.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp?rev=46351&r1=46350&r2=46351&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp Fri Jan 25 04:10:33 2008
@@ -261,9 +261,6 @@
   for (BasicBlock::iterator BBI = BB.end(); BBI != BB.begin(); ){
     --BBI;
     
-    if (deadPointers.empty())
-      break;
-    
     // If we find a store whose pointer is dead...
     if (StoreInst* S = dyn_cast<StoreInst>(BBI)) {
       if (!S->isVolatile()) {
@@ -271,8 +268,12 @@
         // See through pointer-to-pointer bitcasts
         TranslatePointerBitCasts(pointerOperand);
       
-        if (isa<AllocaInst>(pointerOperand) && 
-            deadPointers.count(cast<AllocaInst>(pointerOperand))) {
+        // Alloca'd pointers or byval arguments (which are functionally like
+        // alloca's) are valid candidates for removal.
+        if ( (isa<AllocaInst>(pointerOperand) && 
+              deadPointers.count(cast<AllocaInst>(pointerOperand))) ||
+             (isa<Argument>(pointerOperand) &&
+              cast<Argument>(pointerOperand)->hasByValAttr())) {
           // Remove it!
           MD.removeInstruction(S);
         

Added: llvm/trunk/test/Transforms/DeadStoreElimination/byval.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/DeadStoreElimination/byval.ll?rev=46351&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/DeadStoreElimination/byval.ll (added)
+++ llvm/trunk/test/Transforms/DeadStoreElimination/byval.ll Fri Jan 25 04:10:33 2008
@@ -0,0 +1,10 @@
+; RUN: llvm-as < %s | opt -dse | llvm-dis | not grep store
+
+%struct.x = type { i32, i32, i32, i32 }
+
+define i32 @foo(%struct.x* byval  %a) nounwind  {
+entry:
+	%tmp2 = getelementptr %struct.x* %a, i32 0, i32 0
+	store i32 1, i32* %tmp2, align 4
+	ret i32 1
+}