X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTransforms%2FScalar%2FCorrelatedValuePropagation.cpp;h=b1809b7fae08caa80e0e4caa24a226e5b83b14c6;hb=cf0db29df20d9c665da7e82bb261bdd7cf7f1b2b;hp=075c0351534dc1d196c0a59dc61075a661d8bd7a;hpb=851b04c9208732b502156a66893fd83ca24c5b69;p=oota-llvm.git

diff --git a/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 075c0351534..b1809b7fae0 100644
--- a/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -19,6 +19,7 @@
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Instructions.h"
+#include "llvm/IR/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
@@ -55,7 +56,7 @@ namespace {
       AU.addRequired<LazyValueInfo>();
     }
   };
-}
+} // namespace
 
 char CorrelatedValuePropagation::ID = 0;
 INITIALIZE_PASS_BEGIN(CorrelatedValuePropagation, "correlated-propagation",
@@ -73,7 +74,7 @@ bool CorrelatedValuePropagation::processSelect(SelectInst *S) {
   if (S->getType()->isVectorTy()) return false;
   if (isa<Constant>(S->getOperand(0))) return false;
 
-  Constant *C = LVI->getConstant(S->getOperand(0), S->getParent());
+  Constant *C = LVI->getConstant(S->getOperand(0), S->getParent(), S);
   if (!C) return false;
 
   ConstantInt *CI = dyn_cast<ConstantInt>(C);
@@ -100,34 +101,55 @@ bool CorrelatedValuePropagation::processPHI(PHINode *P) {
     Value *Incoming = P->getIncomingValue(i);
     if (isa<Constant>(Incoming)) continue;
 
-    Value *V = LVI->getConstantOnEdge(Incoming, P->getIncomingBlock(i), BB);
+    Value *V = LVI->getConstantOnEdge(Incoming, P->getIncomingBlock(i), BB, P);
 
-    // Look if the incoming value is a select with a constant but LVI tells us
-    // that the incoming value can never be that constant. In that case replace
-    // the incoming value with the other value of the select. This often allows
-    // us to remove the select later.
+    // Look if the incoming value is a select with a scalar condition for which
+    // LVI can tells us the value. In that case replace the incoming value with
+    // the appropriate value of the select. This often allows us to remove the
+    // select later.
     if (!V) {
       SelectInst *SI = dyn_cast<SelectInst>(Incoming);
       if (!SI) continue;
 
-      Constant *C = dyn_cast<Constant>(SI->getFalseValue());
-      if (!C) continue;
+      Value *Condition = SI->getCondition();
+      if (!Condition->getType()->isVectorTy()) {
+        if (Constant *C = LVI->getConstantOnEdge(
+                Condition, P->getIncomingBlock(i), BB, P)) {
+          if (C->isOneValue()) {
+            V = SI->getTrueValue();
+          } else if (C->isZeroValue()) {
+            V = SI->getFalseValue();
+          }
+          // Once LVI learns to handle vector types, we could also add support
+          // for vector type constants that are not all zeroes or all ones.
+        }
+      }
 
-      if (LVI->getPredicateOnEdge(ICmpInst::ICMP_EQ, SI, C,
-                                  P->getIncomingBlock(i), BB) !=
-          LazyValueInfo::False)
-        continue;
+      // Look if the select has a constant but LVI tells us that the incoming
+      // value can never be that constant. In that case replace the incoming
+      // value with the other value of the select. This often allows us to
+      // remove the select later.
+      if (!V) {
+        Constant *C = dyn_cast<Constant>(SI->getFalseValue());
+        if (!C) continue;
+
+        if (LVI->getPredicateOnEdge(ICmpInst::ICMP_EQ, SI, C,
+              P->getIncomingBlock(i), BB, P) !=
+            LazyValueInfo::False)
+          continue;
+        V = SI->getTrueValue();
+      }
 
       DEBUG(dbgs() << "CVP: Threading PHI over " << *SI << '\n');
-      V = SI->getTrueValue();
     }
 
     P->setIncomingValue(i, V);
     Changed = true;
   }
 
-  // FIXME: Provide DL, TLI, DT, AT to SimplifyInstruction.
-  if (Value *V = SimplifyInstruction(P)) {
+  // FIXME: Provide TLI, DT, AT to SimplifyInstruction.
+  const DataLayout &DL = BB->getModule()->getDataLayout();
+  if (Value *V = SimplifyInstruction(P, DL)) {
     P->replaceAllUsesWith(V);
     P->eraseFromParent();
     Changed = true;
@@ -148,7 +170,7 @@ bool CorrelatedValuePropagation::processMemAccess(Instruction *I) {
 
   if (isa<Constant>(Pointer)) return false;
 
-  Constant *C = LVI->getConstant(Pointer, I->getParent());
+  Constant *C = LVI->getConstant(Pointer, I->getParent(), I);
   if (!C) return false;
 
   ++NumMemAccess;
@@ -174,13 +196,15 @@ bool CorrelatedValuePropagation::processCmp(CmpInst *C) {
   if (PI == PE) return false;
 
   LazyValueInfo::Tristate Result = LVI->getPredicateOnEdge(C->getPredicate(),
-                                    C->getOperand(0), Op1, *PI, C->getParent());
+                                    C->getOperand(0), Op1, *PI,
+                                    C->getParent(), C);
   if (Result == LazyValueInfo::Unknown) return false;
 
   ++PI;
   while (PI != PE) {
     LazyValueInfo::Tristate Res = LVI->getPredicateOnEdge(C->getPredicate(),
-                                    C->getOperand(0), Op1, *PI, C->getParent());
+                                    C->getOperand(0), Op1, *PI,
+                                    C->getParent(), C);
     if (Res != Result) return false;
     ++PI;
   }
@@ -230,7 +254,8 @@ bool CorrelatedValuePropagation::processSwitch(SwitchInst *SI) {
     for (pred_iterator PI = PB; PI != PE; ++PI) {
       // Is the switch condition equal to the case value?
       LazyValueInfo::Tristate Value = LVI->getPredicateOnEdge(CmpInst::ICMP_EQ,
-                                                              Cond, Case, *PI, BB);
+                                                              Cond, Case, *PI,
+                                                              BB, SI);
       // Give up on this case if nothing is known.
       if (Value == LazyValueInfo::Unknown) {
         State = LazyValueInfo::Unknown;