[InstCombine] use 'match' to reduce code bloat; NFCI

I wrote this patch before seeing the comment in:
https://reviews.llvm.org/D27114
...that suggests we should actually be canonicalizing the other way.

So just in case we decide this is the right way, we might as well
have a cleaner implementation.

llvm-svn: 290912

1 files changed, 11 insertions, 15 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index e80b55320e7..b39649c6dea 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -2713,24 +2713,20 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
 
     // assume( (load addr) != null ) -> add 'nonnull' metadata to load
     // (if assume is valid at the load)
-    if (ICmpInst* ICmp = dyn_cast<ICmpInst>(IIOperand)) {
-      Value *LHS = ICmp->getOperand(0);
-      Value *RHS = ICmp->getOperand(1);
-      if (ICmpInst::ICMP_NE == ICmp->getPredicate() &&
-          isa<LoadInst>(LHS) &&
-          isa<Constant>(RHS) &&
-          RHS->getType()->isPointerTy() &&
-          cast<Constant>(RHS)->isNullValue()) {
-        LoadInst* LI = cast<LoadInst>(LHS);
-        if (isValidAssumeForContext(II, LI, &DT)) {
-          MDNode *MD = MDNode::get(II->getContext(), None);
-          LI->setMetadata(LLVMContext::MD_nonnull, MD);
-          return eraseInstFromFunction(*II);
-        }
-      }
+    CmpInst::Predicate Pred;
+    Instruction *LHS;
+    if (match(IIOperand, m_ICmp(Pred, m_Instruction(LHS), m_Zero())) &&
+        Pred == ICmpInst::ICMP_NE && LHS->getOpcode() == Instruction::Load &&
+        LHS->getType()->isPointerTy() &&
+        isValidAssumeForContext(II, LHS, &DT)) {
+      MDNode *MD = MDNode::get(II->getContext(), None);
+      LHS->setMetadata(LLVMContext::MD_nonnull, MD);
+      return eraseInstFromFunction(*II);
+
       // TODO: apply nonnull return attributes to calls and invokes
       // TODO: apply range metadata for range check patterns?
     }
+
     // If there is a dominating assume with the same condition as this one,
     // then this one is redundant, and should be removed.
     APInt KnownZero(1, 0), KnownOne(1, 0);