[llvm-commits] [llvm] r86067 - in /llvm/trunk: lib/Transforms/Scalar/DeadStoreElimination.cpp lib/Transforms/Scalar/JumpThreading.cpp test/Transforms/DeadStoreElimination/no-targetdata.ll

[Chris Lattner]

Author: lattner
Date: Wed Nov  4 17:20:12 2009
New Revision: 86067

URL: http://llvm.org/viewvc/llvm-project?rev=86067&view=rev
Log:
improve DSE when TargetData is not around, based on work by
Hans Wennborg!

Added:
    llvm/trunk/test/Transforms/DeadStoreElimination/no-targetdata.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp
    llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp?rev=86067&r1=86066&r2=86067&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp Wed Nov  4 17:20:12 2009
@@ -78,6 +78,21 @@
 
 FunctionPass *llvm::createDeadStoreEliminationPass() { return new DSE(); }
 
+/// isValueAtLeastAsBigAs - Return true if V1 is greater than or equal to the
+/// stored size of V2.  This returns false if we don't know.
+///
+static bool isValueAtLeastAsBigAs(Value *V1, Value *V2, const TargetData *TD) {
+  const Type *V1Ty = V1->getType(), *V2Ty = V2->getType();
+  
+  // Exactly the same type, must have exactly the same size.
+  if (V1Ty == V2Ty) return true;
+  
+  // If we don't have target data, we don't know.
+  if (TD == 0) return false;
+  
+  return TD->getTypeStoreSize(V1Ty) >= TD->getTypeStoreSize(V2Ty);
+}
+
 bool DSE::runOnBasicBlock(BasicBlock &BB) {
   MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
   TD = getAnalysisIfAvailable<TargetData>();
@@ -118,9 +133,7 @@
     // If this is a store-store dependence, then the previous store is dead so
     // long as this store is at least as big as it.
     if (StoreInst *DepStore = dyn_cast<StoreInst>(InstDep.getInst()))
-      if (TD &&
-          TD->getTypeStoreSize(DepStore->getOperand(0)->getType()) <=
-          TD->getTypeStoreSize(SI->getOperand(0)->getType())) {
+      if (isValueAtLeastAsBigAs(SI->getOperand(0), DepStore->getOperand(0),TD)){
         // Delete the store and now-dead instructions that feed it.
         DeleteDeadInstruction(DepStore);
         NumFastStores++;

Modified: llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp?rev=86067&r1=86066&r2=86067&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp Wed Nov  4 17:20:12 2009
@@ -68,9 +68,6 @@
     static char ID; // Pass identification
     JumpThreading() : FunctionPass(&ID) {}
 
-    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
-    }
-
     bool runOnFunction(Function &F);
     void FindLoopHeaders(Function &F);
     

Added: llvm/trunk/test/Transforms/DeadStoreElimination/no-targetdata.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/DeadStoreElimination/no-targetdata.ll?rev=86067&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/DeadStoreElimination/no-targetdata.ll (added)
+++ llvm/trunk/test/Transforms/DeadStoreElimination/no-targetdata.ll Wed Nov  4 17:20:12 2009
@@ -0,0 +1,15 @@
+; RUN: opt %s -dse -S | FileCheck %s
+
+declare void @test1f()
+
+define void @test1(i32* noalias %p) {
+       store i32 1, i32* %p;
+       call void @test1f()
+       store i32 2, i32 *%p
+       ret void
+; CHECK: define void @test1
+; CHECK-NOT: store
+; CHECK-NEXT: call void
+; CHECK-NEXT: store i32 2
+; CHECK-NEXT: ret void
+}
\ No newline at end of file