[ConstnatFolding] Teach the folder how to fold ConstantVector

A ConstantVector can have ConstantExpr operands and vice versa.
However, the folder had no ability to fold ConstantVectors which, in
some cases, was an optimization barrier.

Instead, rephrase the folder in terms of Constants instead of
ConstantExprs and teach callers how to deal with failure.

llvm-svn: 277099

3 files changed, 13 insertions, 12 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index d41c449c7d2..840feca3338 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -161,9 +161,8 @@ Value *InstCombiner::EvaluateInDifferentType(Value *V, Type *Ty,
   if (Constant *C = dyn_cast<Constant>(V)) {
     C = ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
     // If we got a constantexpr back, try to simplify it with DL info.
-    if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
-      if (Constant *FoldedC = ConstantFoldConstantExpression(CE, DL, TLI))
-        C = FoldedC;
+    if (Constant *FoldedC = ConstantFoldConstant(C, DL, TLI))
+      C = FoldedC;
     return C;
   }
 
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
index 08e16a7ee1a..279eaad0174 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -194,8 +194,10 @@ static Value *GetShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
     else
       V = IC.Builder->CreateLShr(C, NumBits);
     // If we got a constantexpr back, try to simplify it with TD info.
-    if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
-      V = ConstantFoldConstantExpression(CE, DL, IC.getTargetLibraryInfo());
+    if (auto *C = dyn_cast<Constant>(V))
+      if (auto *FoldedC =
+              ConstantFoldConstant(C, DL, IC.getTargetLibraryInfo()))
+        V = FoldedC;
     return V;
   }
 
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 377ccb9c37f..6e4c823901a 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2981,7 +2981,7 @@ static bool AddReachableCodeToWorklist(BasicBlock *BB, const DataLayout &DL,
   Worklist.push_back(BB);
 
   SmallVector<Instruction*, 128> InstrsForInstCombineWorklist;
-  DenseMap<ConstantExpr*, Constant*> FoldedConstants;
+  DenseMap<Constant *, Constant *> FoldedConstants;
 
   do {
     BB = Worklist.pop_back_val();
@@ -3017,17 +3017,17 @@ static bool AddReachableCodeToWorklist(BasicBlock *BB, const DataLayout &DL,
       // See if we can constant fold its operands.
       for (User::op_iterator i = Inst->op_begin(), e = Inst->op_end(); i != e;
            ++i) {
-        ConstantExpr *CE = dyn_cast<ConstantExpr>(i);
-        if (CE == nullptr)
+        if (!isa<ConstantVector>(i) && !isa<ConstantExpr>(i))
           continue;
 
-        Constant *&FoldRes = FoldedConstants[CE];
+        auto *C = cast<Constant>(i);
+        Constant *&FoldRes = FoldedConstants[C];
         if (!FoldRes)
-          FoldRes = ConstantFoldConstantExpression(CE, DL, TLI);
+          FoldRes = ConstantFoldConstant(C, DL, TLI);
         if (!FoldRes)
-          FoldRes = CE;
+          FoldRes = C;
 
-        if (FoldRes != CE) {
+        if (FoldRes != C) {
           *i = FoldRes;
           MadeIRChange = true;
         }