Revert commits r237521 and r237520.

The AArch64 LNT bot is unhappy - I've found that the problem is in
SimpliftDemandedBits, but that's going to require another code review
so reverting in the meantime.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237528 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/InstCombine/InstCombineCasts.cpp

@@ -435,15 +435,6 @@ Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
   if (Instruction *Result = commonCastTransforms(CI))
     return Result;
 
-  // Test if the trunc is the user of a select which is part of a
-  // minimum or maximum operation. If so, don't do any more simplification.
-  // Even simplifying demanded bits can break the canonical form of a 
-  // min/max.
-  Value *LHS, *RHS;
-  if (SelectInst *SI = dyn_cast<SelectInst>(CI.getOperand(0)))
-    if (matchSelectPattern(SI, LHS, RHS) != SPF_UNKNOWN)
-      return nullptr;
-  
   // See if we can simplify any instructions used by the input whose sole
   // purpose is to compute bits we don't care about.
   if (SimplifyDemandedInstructionBits(CI))

lib/Transforms/InstCombine/InstCombineCompares.cpp

@@ -3970,19 +3970,6 @@ Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
     }
   }
 
-  // Test if the FCmpInst instruction is used exclusively by a select as
-  // part of a minimum or maximum operation. If so, refrain from doing
-  // any other folding. This helps out other analyses which understand
-  // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
-  // and CodeGen. And in this case, at least one of the comparison
-  // operands has at least one user besides the compare (the select),
-  // which would often largely negate the benefit of folding anyway.
-  if (I.hasOneUse())
-    if (SelectInst *SI = dyn_cast<SelectInst>(*I.user_begin()))
-      if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
-          (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
-        return nullptr;
-
   // Handle fcmp with constant RHS
   if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
     if (Instruction *LHSI = dyn_cast<Instruction>(Op0))

lib/Transforms/InstCombine/InstCombineSelect.cpp

@@ -1154,30 +1154,18 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
       }
 
   // See if we can fold the select into one of our operands.
-  if (SI.getType()->isIntOrIntVectorTy()) {
+  if (SI.getType()->isIntegerTy()) {
     if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal))
       return FoldI;
 
     Value *LHS, *RHS, *LHS2, *RHS2;
-    Instruction::CastOps CastOp;
-    SelectPatternFlavor SPF = matchSelectPattern(&SI, LHS, RHS, &CastOp);
+    SelectPatternFlavor SPF = matchSelectPattern(&SI, LHS, RHS);
 
+    // MAX(MAX(a, b), a) -> MAX(a, b)
+    // MIN(MIN(a, b), a) -> MIN(a, b)
+    // MAX(MIN(a, b), a) -> a
+    // MIN(MAX(a, b), a) -> a
     if (SPF) {
-      // Canonicalize so that type casts are outside select patterns.
-      if (LHS->getType()->getPrimitiveSizeInBits() !=
-          SI.getType()->getPrimitiveSizeInBits()) {
-        CmpInst::Predicate Pred = getICmpPredicateForMinMax(SPF);
-        Value *Cmp = Builder->CreateICmp(Pred, LHS, RHS);
-        Value *NewSI = Builder->CreateCast(CastOp,
-                                           Builder->CreateSelect(Cmp, LHS, RHS),
-                                           SI.getType());
-        return ReplaceInstUsesWith(SI, NewSI);
-      }
-
-      // MAX(MAX(a, b), a) -> MAX(a, b)
-      // MIN(MIN(a, b), a) -> MIN(a, b)
-      // MAX(MIN(a, b), a) -> a
-      // MIN(MAX(a, b), a) -> a
       if (SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2))
         if (Instruction *R = FoldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2,
                                           SI, SPF, RHS))

lib/Transforms/InstCombine/InstructionCombining.cpp

@@ -714,22 +714,6 @@ Instruction *InstCombiner::FoldOpIntoSelect(Instruction &Op, SelectInst *SI) {
         return nullptr;
     }
 
-    // Test if a CmpInst instruction is used exclusively by a select as
-    // part of a minimum or maximum operation. If so, refrain from doing
-    // any other folding. This helps out other analyses which understand
-    // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
-    // and CodeGen. And in this case, at least one of the comparison
-    // operands has at least one user besides the compare (the select),
-    // which would often largely negate the benefit of folding anyway.
-    if (auto *CI = dyn_cast<CmpInst>(SI->getCondition())) {
-      if (CI->hasOneUse()) {
-        Value *Op0 = CI->getOperand(0), *Op1 = CI->getOperand(1);
-        if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
-            (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
-          return nullptr;
-      }
-    }
-
     Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, this);
     Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, this);
 
@@ -739,6 +723,7 @@ Instruction *InstCombiner::FoldOpIntoSelect(Instruction &Op, SelectInst *SI) {
   return nullptr;
 }
 
+
 /// FoldOpIntoPhi - Given a binary operator, cast instruction, or select which
 /// has a PHI node as operand #0, see if we can fold the instruction into the
 /// PHI (which is only possible if all operands to the PHI are constants).