[PATCH] D47144: [InstCombine] Fix PR37526: MinMax patterns produce an infinite loop.

[Sanjay Patel via Phabricator via llvm-commits]

spatel added inline comments.


================
Comment at: lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp:462-467
+  Value *NewPtr = nullptr;
+  if (auto *BC = dyn_cast<BitCastInst>(Ptr)) {
+    Value *Op0 = BC->getOperand(0);
+    if (Op0->getType()->getPointerElementType() == NewTy &&
+        Op0->getType()->getPointerAddressSpace() == AS)
+      NewPtr = Op0;
----------------
Use a matcher to simplify this?

  Value *NewPtr;
  if (!(match(Ptr, m_BitCast(m_Value(NewPtr))) &&
        NewPtr->getType()->getPointerElementType() == NewTy &&
        NewPtr->getType()->getPointerAddressSpace() == AS))
    NewPtr = IC.Builder.CreateBitCast(Ptr, NewTy->getPointerTo(AS));



================
Comment at: test/Transforms/InstCombine/PR37526.ll:4-6
+%struct.x5 = type { i32 (...)**, i32, i32 }
+
+define void @repro(%struct.x5*, %struct.x5* %x12, %struct.x5* %x13) {
----------------
We shouldn't need a struct or loop to repro - something like this should be ok?

```
define void @PR37526(i32* %pz, i32* %px, i32* %py) {
  %t1 = bitcast i32* %pz to i64*
  %t2 = load i32, i32* %py
  %t3 = load i32, i32* %px
  %cmp = icmp slt i32 %t2, %t3
  %select = select i1 %cmp, i32* %px, i32* %py
  %bc = bitcast i32* %select to i64*
  %r = load i64, i64* %bc
  store i64 %r, i64* %t1
  ret void
}

```


Repository:
  rL LLVM

https://reviews.llvm.org/D47144