[LVI] Relax the assertion about LVILatticeVal type in getConstantRange

[apilipenko]

Summary

The problem was triggered by my recent change in CVP (D23059). Current code expected that integer constants are represented by constantrange LVILatticeVal and never represented as LVILatticeVal with constant tag. That is true for ConstantInt constants, although ConstantExpr integer type constants are legally represented as constant LVILatticeVal.

This code fails with CVP change in:

@b = global i32 0, align 4
define void @test6(i32 %a) {
bb:
  %add = add i32 %a, ptrtoint (i32* @b to i32)
  ret void
}

Currently getConstantRange code is not executed by any of the upstream passes. I'm going to add a test case to test/Transforms/CorrelatedValuePropagation/add.ll once I resubmit the CVP change.

[apilipenko]

Upload the diff with full context.

[sanjoy]

lgtm with one nit inline

lib/Analysis/LazyValueInfo.cpp

1524

I'd sink Result.isConstant() into the assert.

lib/Analysis/LazyValueInfo.cpp

 
 ConstantRange LazyValueInfo::getConstantRange(Value *V, BasicBlock *BB,
                                               Instruction *CxtI) {
   assert(V->getType()->isIntegerTy());
   unsigned Width = V->getType()->getIntegerBitWidth();
   const DataLayout &DL = BB->getModule()->getDataLayout();
   LVILatticeVal Result =
       getCache(PImpl, AC, &DL, DT).getValueInBlock(V, BB, CxtI);
-  assert(!Result.isConstant());
   if (Result.isUndefined())
     return ConstantRange(Width, /*isFullSet=*/false);
   if (Result.isConstantRange())
     return Result.getConstantRange();
+  if (Result.isConstant())
+    // We represent ConstantInt constants as constant ranges but other kinds
+    // of integer constants, i.e. ConstantExpr will be tagged as constants
+    assert(!isa<ConstantInt>(Result.getConstant()) &&
+           "ConstantInt value must be represented as constantrange");
   return ConstantRange(Width, /*isFullSet=*/true);
 }
 
 /// Determine whether the specified value is known to be a
 /// constant on the specified edge. Return null if not.
 Constant *LazyValueInfo::getConstantOnEdge(Value *V, BasicBlock *FromBB,
                                            BasicBlock *ToBB,
                                            Instruction *CxtI) {