Enhance the memdep interface so that users can tell the difference between a dependency which cannot be calculated and a path reaching the entry point of the function. This patch introduces isNonFuncLocal, which replaces isUnknown in some cases.

Patch by Xiaoyi Guo.

llvm-svn: 141896

2 files changed, 13 insertions, 13 deletions

diff --git a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
index ffa77098bc8..a593d0f4463 100644
--- a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -441,7 +441,7 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
 
     // Ignore any store where we can't find a local dependence.
     // FIXME: cross-block DSE would be fun. :)
-    if (InstDep.isNonLocal() || InstDep.isUnknown())
+    if (!InstDep.isDef() && !InstDep.isClobber())
       continue;
 
     // If we're storing the same value back to a pointer that we just
@@ -477,7 +477,7 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
     if (Loc.Ptr == 0)
       continue;
 
-    while (!InstDep.isNonLocal() && !InstDep.isUnknown()) {
+    while (InstDep.isDef() || InstDep.isClobber()) {
       // Get the memory clobbered by the instruction we depend on.  MemDep will
       // skip any instructions that 'Loc' clearly doesn't interact with.  If we
       // end up depending on a may- or must-aliased load, then we can't optimize
@@ -545,7 +545,7 @@ bool DSE::HandleFree(CallInst *F) {
 
   MemDepResult Dep = MD->getDependency(F);
 
-  while (!Dep.isNonLocal() && !Dep.isUnknown()) {
+  while (Dep.isDef() || Dep.isClobber()) {
     Instruction *Dependency = Dep.getInst();
     if (!hasMemoryWrite(Dependency) || !isRemovable(Dependency))
       return MadeChange;
diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index d94f5045859..cbfdbcddaec 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -1279,7 +1279,9 @@ bool GVN::processNonLocalLoad(LoadInst *LI) {
 
   // If we had a phi translation failure, we'll have a single entry which is a
   // clobber in the current block.  Reject this early.
-  if (Deps.size() == 1 && Deps[0].getResult().isUnknown()) {
+  if (Deps.size() == 1
+      && !Deps[0].getResult().isDef() && !Deps[0].getResult().isClobber())
+  {
     DEBUG(
       dbgs() << "GVN: non-local load ";
       WriteAsOperand(dbgs(), LI);
@@ -1299,7 +1301,7 @@ bool GVN::processNonLocalLoad(LoadInst *LI) {
     BasicBlock *DepBB = Deps[i].getBB();
     MemDepResult DepInfo = Deps[i].getResult();
 
-    if (DepInfo.isUnknown()) {
+    if (!DepInfo.isDef() && !DepInfo.isClobber()) {
       UnavailableBlocks.push_back(DepBB);
       continue;
     }
@@ -1364,7 +1366,7 @@ bool GVN::processNonLocalLoad(LoadInst *LI) {
       continue;
     }
 
-    assert(DepInfo.isDef() && "Expecting def here");
+    // DepInfo.isDef() here
 
     Instruction *DepInst = DepInfo.getInst();
 
@@ -1761,7 +1763,11 @@ bool GVN::processLoad(LoadInst *L) {
     return false;
   }
 
-  if (Dep.isUnknown()) {
+  // If it is defined in another block, try harder.
+  if (Dep.isNonLocal())
+    return processNonLocalLoad(L);
+
+  if (!Dep.isDef()) {
     DEBUG(
       // fast print dep, using operator<< on instruction is too slow.
       dbgs() << "GVN: load ";
@@ -1771,12 +1777,6 @@ bool GVN::processLoad(LoadInst *L) {
     return false;
   }
 
-  // If it is defined in another block, try harder.
-  if (Dep.isNonLocal())
-    return processNonLocalLoad(L);
-
-  assert(Dep.isDef() && "Expecting def here");
-
   Instruction *DepInst = Dep.getInst();
   if (StoreInst *DepSI = dyn_cast<StoreInst>(DepInst)) {
     Value *StoredVal = DepSI->getValueOperand();