From: Owen Anderson <resistor@mac.com>
Date: Wed, 14 Jul 2010 23:33:51 +0000 (+0000)
Subject: Add instcombine transforms to optimize tests of multiple bits of the same value into... 
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=bd129a746058dc5d8da089f1351ff417de3114e7

Add instcombine transforms to optimize tests of multiple bits of the same value into a single larger comparison.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108378 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 3f4a857c41a..57cd76dab09 100644
--- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -472,6 +472,24 @@ Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
       Value *NewOr = Builder->CreateOr(Val, Val2);
       return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
     }
+    
+    // (icmp ne (A & C1) 0) & (icmp ne (A & C2), 0) -->
+    // (icmp eq (A & (C1|C2)), (C1|C2))
+    if (LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) {
+      Instruction *I1 = dyn_cast<Instruction>(Val);
+      Instruction *I2 = dyn_cast<Instruction>(Val2);
+      if (I1 && I1->getOpcode() == Instruction::And &&
+          I2 && I2->getOpcode() == Instruction::And &&
+          I1->getOperand(0) == I1->getOperand(0)) {
+        ConstantInt *CI1 = dyn_cast<ConstantInt>(I1->getOperand(1));
+        ConstantInt *CI2 = dyn_cast<ConstantInt>(I2->getOperand(1));
+        if (CI1 && CI2) {
+          Constant *ConstOr = ConstantExpr::getOr(CI1, CI2);
+          Value *NewAnd = Builder->CreateAnd(I1->getOperand(0), ConstOr);
+          return Builder->CreateICmp(ICmpInst::ICMP_EQ, NewAnd, ConstOr);
+        }
+      }
+    }
   }
   
   // From here on, we only handle:
diff --git a/lib/Transforms/InstCombine/InstCombineSelect.cpp b/lib/Transforms/InstCombine/InstCombineSelect.cpp
index c44fe9db6e3..c85d74ad7de 100644
--- a/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -699,6 +699,31 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
     SI.setOperand(2, TrueVal);
     return &SI;
   }
+  
+  // select (or (A == 0) (B == 0)) T, F--> select (and (A != 0) (B != 0)) F, T
+  // Note: This is a canonicalization rather than an optimization, and is used
+  // to expose opportunities to other instcombine transforms.
+  Instruction* CondInst = dyn_cast<Instruction>(CondVal);
+  if (CondInst && CondInst->getOpcode() == Instruction::Or) {
+    ICmpInst *LHSCmp = dyn_cast<ICmpInst>(CondInst->getOperand(0));
+    ICmpInst *RHSCmp = dyn_cast<ICmpInst>(CondInst->getOperand(1));
+    if (LHSCmp && LHSCmp->getPredicate() == ICmpInst::ICMP_EQ &&
+        RHSCmp && RHSCmp->getPredicate() == ICmpInst::ICMP_EQ) {
+      ConstantInt* C1 = dyn_cast<ConstantInt>(LHSCmp->getOperand(1));
+      ConstantInt* C2 = dyn_cast<ConstantInt>(RHSCmp->getOperand(1));
+      if (C1 && C1->isZero() && C2 && C2->isZero()) {
+        LHSCmp->setPredicate(ICmpInst::ICMP_NE);
+        RHSCmp->setPredicate(ICmpInst::ICMP_NE);
+        Value *And =
+          InsertNewInstBefore(BinaryOperator::CreateAnd(LHSCmp, RHSCmp,
+                                             "and."+CondVal->getName()), SI);
+        SI.setOperand(0, And);
+        SI.setOperand(1, FalseVal);
+        SI.setOperand(2, TrueVal);
+        return &SI;
+      }
+    }
+  }
 
   return 0;
 }