Revert most of r225597

We can't rely on a DataLayout enlightened constant folder.

llvm-svn: 225599

1 files changed, 30 insertions, 47 deletions

diff --git a/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp b/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp
index 6d5ee4dc516..e4c58d42c5d 100644
--- a/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp
+++ b/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp
@@ -13,10 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "X86ShuffleDecode.h"
-#include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/IR/Constants.h"
-#include "llvm/IR/DataLayout.h"
-#include "llvm/IR/InstrTypes.h"
 #include "llvm/CodeGen/MachineValueType.h"
 
 //===----------------------------------------------------------------------===//
@@ -256,8 +253,7 @@ void DecodeVPERM2X128Mask(MVT VT, unsigned Imm,
   }
 }
 
-void DecodePSHUFBMask(const Constant *C, const DataLayout *TD,
-                      SmallVectorImpl<int> &ShuffleMask) {
+void DecodePSHUFBMask(const Constant *C, SmallVectorImpl<int> &ShuffleMask) {
   Type *MaskTy = C->getType();
   // It is not an error for the PSHUFB mask to not be a vector of i8 because the
   // constant pool uniques constants by their bit representation.
@@ -266,56 +262,43 @@ void DecodePSHUFBMask(const Constant *C, const DataLayout *TD,
   //
   //   <2 x i64> <i64 -9223372034707292160, i64 -9223372034707292160>
   //
-  //   <4 x i32> <i32 -2147483648, i32 -2147483648, i32 -2147483648, i32
-  //   -2147483648>
+  //   <4 x i32> <i32 -2147483648, i32 -2147483648,
+  //              i32 -2147483648, i32 -2147483648>
 
   unsigned MaskTySize = MaskTy->getPrimitiveSizeInBits();
 
-  VectorType *DestTy = nullptr;
-  if (MaskTySize == 128)
-    DestTy = VectorType::get(Type::getInt8Ty(MaskTy->getContext()), 16);
-  else if (MaskTySize == 256)
-    DestTy = VectorType::get(Type::getInt8Ty(MaskTy->getContext()), 32);
-
-  // FIXME: Add support for AVX-512.
-  if (!DestTy)
+  if (MaskTySize != 128 && MaskTySize != 256) // FIXME: Add support for AVX-512.
     return;
 
-  if (DestTy != MaskTy) {
-    if (!CastInst::castIsValid(Instruction::BitCast, const_cast<Constant *>(C),
-                               DestTy))
-      return;
-
-    C = ConstantFoldInstOperands(Instruction::BitCast, DestTy,
-                                 const_cast<Constant *>(C), TD);
-    MaskTy = DestTy;
-  }
+  // This is a straightforward byte vector.
+  if (MaskTy->isVectorTy() && MaskTy->getVectorElementType()->isIntegerTy(8)) {
+    int NumElements = MaskTy->getVectorNumElements();
+    ShuffleMask.reserve(NumElements);
 
-  int NumElements = MaskTy->getVectorNumElements();
-  ShuffleMask.reserve(NumElements);
-
-  for (int i = 0; i < NumElements; ++i) {
-    // For AVX vectors with 32 bytes the base of the shuffle is the 16-byte
-    // lane of the vector we're inside.
-    int Base = i < 16 ? 0 : 16;
-    Constant *COp = C->getAggregateElement(i);
-    if (!COp) {
-      ShuffleMask.clear();
-      return;
-    } else if (isa<UndefValue>(COp)) {
-      ShuffleMask.push_back(SM_SentinelUndef);
-      continue;
-    }
-    uint64_t Element = cast<ConstantInt>(COp)->getZExtValue();
-    // If the high bit (7) of the byte is set, the element is zeroed.
-    if (Element & (1 << 7))
-      ShuffleMask.push_back(SM_SentinelZero);
-    else {
-      // Only the least significant 4 bits of the byte are used.
-      int Index = Base + (Element & 0xf);
-      ShuffleMask.push_back(Index);
+    for (int i = 0; i < NumElements; ++i) {
+      // For AVX vectors with 32 bytes the base of the shuffle is the 16-byte
+      // lane of the vector we're inside.
+      int Base = i < 16 ? 0 : 16;
+      Constant *COp = C->getAggregateElement(i);
+      if (!COp) {
+        ShuffleMask.clear();
+        return;
+      } else if (isa<UndefValue>(COp)) {
+        ShuffleMask.push_back(SM_SentinelUndef);
+        continue;
+      }
+      uint64_t Element = cast<ConstantInt>(COp)->getZExtValue();
+      // If the high bit (7) of the byte is set, the element is zeroed.
+      if (Element & (1 << 7))
+        ShuffleMask.push_back(SM_SentinelZero);
+      else {
+        // Only the least significant 4 bits of the byte are used.
+        int Index = Base + (Element & 0xf);
+        ShuffleMask.push_back(Index);
+      }
     }
   }
+  // TODO: Handle funny-looking vectors too.
 }
 
 void DecodePSHUFBMask(ArrayRef<uint64_t> RawMask,