Revert r257064. It caused failures in some sanitizer tests.

[oota-llvm.git] / lib / Transforms / InstCombine / InstCombineSimplifyDemanded.cpp

diff --git a/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index 955776e0f85cf454259583e0e9829b70db89b1cd..743d51483ea16048fbeb0621a71b49b2b7e54ff8 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "InstCombineInternal.h"
+#include "llvm/Analysis/ValueTracking.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/PatternMatch.h"
 
@@ -406,6 +407,12 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
     break;
   }
   case Instruction::Select:
+    // If this is a select as part of a min/max pattern, don't simplify any
+    // further in case we break the structure.
+    Value *LHS, *RHS;
+    if (matchSelectPattern(I, LHS, RHS).Flavor != SPF_UNKNOWN)
+      return nullptr;
+
     if (SimplifyDemandedBits(I->getOperandUse(2), DemandedMask, RHSKnownZero,
                              RHSKnownOne, Depth + 1) ||
         SimplifyDemandedBits(I->getOperandUse(1), DemandedMask, LHSKnownZero,
@@ -1050,7 +1057,13 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
     APInt LeftDemanded(DemandedElts), RightDemanded(DemandedElts);
     if (ConstantVector* CV = dyn_cast<ConstantVector>(I->getOperand(0))) {
       for (unsigned i = 0; i < VWidth; i++) {
-        if (CV->getAggregateElement(i)->isNullValue())
+        Constant *CElt = CV->getAggregateElement(i);
+        // Method isNullValue always returns false when called on a
+        // ConstantExpr. If CElt is a ConstantExpr then skip it in order to
+        // to avoid propagating incorrect information.
+        if (isa<ConstantExpr>(CElt))
+          continue;
+        if (CElt->isNullValue())
           LeftDemanded.clearBit(i);
         else
           RightDemanded.clearBit(i);
@@ -1075,6 +1088,7 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
     if (!VTy) break;
     unsigned InVWidth = VTy->getNumElements();
     APInt InputDemandedElts(InVWidth, 0);
+    UndefElts2 = APInt(InVWidth, 0);
     unsigned Ratio;
 
     if (VWidth == InVWidth) {
@@ -1082,29 +1096,25 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
       // elements as are demanded of us.
       Ratio = 1;
       InputDemandedElts = DemandedElts;
-    } else if (VWidth > InVWidth) {
-      // Untested so far.
-      break;
-
-      // If there are more elements in the result than there are in the source,
-      // then an input element is live if any of the corresponding output
-      // elements are live.
-      Ratio = VWidth/InVWidth;
-      for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) {
+    } else if ((VWidth % InVWidth) == 0) {
+      // If the number of elements in the output is a multiple of the number of
+      // elements in the input then an input element is live if any of the
+      // corresponding output elements are live.
+      Ratio = VWidth / InVWidth;
+      for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
         if (DemandedElts[OutIdx])
-          InputDemandedElts.setBit(OutIdx/Ratio);
-      }
-    } else {
-      // Untested so far.
-      break;
-
-      // If there are more elements in the source than there are in the result,
-      // then an input element is live if the corresponding output element is
-      // live.
-      Ratio = InVWidth/VWidth;
+          InputDemandedElts.setBit(OutIdx / Ratio);
+    } else if ((InVWidth % VWidth) == 0) {
+      // If the number of elements in the input is a multiple of the number of
+      // elements in the output then an input element is live if the
+      // corresponding output element is live.
+      Ratio = InVWidth / VWidth;
       for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
-        if (DemandedElts[InIdx/Ratio])
+        if (DemandedElts[InIdx / Ratio])
           InputDemandedElts.setBit(InIdx);
+    } else {
+      // Unsupported so far.
+      break;
     }
 
     // div/rem demand all inputs, because they don't want divide by zero.
@@ -1115,24 +1125,26 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
       MadeChange = true;
     }
 
-    UndefElts = UndefElts2;
-    if (VWidth > InVWidth) {
-      llvm_unreachable("Unimp");
-      // If there are more elements in the result than there are in the source,
-      // then an output element is undef if the corresponding input element is
-      // undef.
+    if (VWidth == InVWidth) {
+      UndefElts = UndefElts2;
+    } else if ((VWidth % InVWidth) == 0) {
+      // If the number of elements in the output is a multiple of the number of
+      // elements in the input then an output element is undef if the
+      // corresponding input element is undef.
       for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
-        if (UndefElts2[OutIdx/Ratio])
+        if (UndefElts2[OutIdx / Ratio])
+          UndefElts.setBit(OutIdx);
+    } else if ((InVWidth % VWidth) == 0) {
+      // If the number of elements in the input is a multiple of the number of
+      // elements in the output then an output element is undef if all of the
+      // corresponding input elements are undef.
+      for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) {
+        APInt SubUndef = UndefElts2.lshr(OutIdx * Ratio).zextOrTrunc(Ratio);
+        if (SubUndef.countPopulation() == Ratio)
           UndefElts.setBit(OutIdx);
-    } else if (VWidth < InVWidth) {
+      }
+    } else {
       llvm_unreachable("Unimp");
-      // If there are more elements in the source than there are in the result,
-      // then a result element is undef if all of the corresponding input
-      // elements are undef.
-      UndefElts = ~0ULL >> (64-VWidth);  // Start out all undef.
-      for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
-        if (!UndefElts2[InIdx])            // Not undef?
-          UndefElts.clearBit(InIdx/Ratio);    // Clear undef bit.
     }
     break;
   }
@@ -1230,6 +1242,15 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
       // like undef&0.  The result is known zero, not undef.
       UndefElts &= UndefElts2;
       break;
+
+    // SSE4A instructions leave the upper 64-bits of the 128-bit result
+    // in an undefined state.
+    case Intrinsic::x86_sse4a_extrq:
+    case Intrinsic::x86_sse4a_extrqi:
+    case Intrinsic::x86_sse4a_insertq:
+    case Intrinsic::x86_sse4a_insertqi:
+      UndefElts |= APInt::getHighBitsSet(VWidth, VWidth / 2);
+      break;
     }
     break;
   }