[PATCH] D62822: [LVI][CVP] Add support for urem, srem and sdiv

[Nikita Popov via Phabricator via llvm-commits]

nikic created this revision.
nikic added reviewers: spatel, lebedev.ri, reames.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.

The underlying ConstantRange functionality has been added in D60952 <https://reviews.llvm.org/D60952>, D61207 <https://reviews.llvm.org/D61207> and D61238 <https://reviews.llvm.org/D61238>, this just exposes it for LVI.

I'm switching the code from using a whitelist to a blacklist, as we're down to one unsupported operation here (xor) and writing it this way seems more obvious :)


Repository:
  rL LLVM

https://reviews.llvm.org/D62822

Files:
  llvm/lib/Analysis/LazyValueInfo.cpp
  llvm/lib/IR/ConstantRange.cpp
  llvm/test/Transforms/CorrelatedValuePropagation/basic.ll


Index: llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
===================================================================
--- llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
+++ llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
@@ -931,7 +931,7 @@
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[UREM]], 30
 ; CHECK-NEXT:    br label [[EXIT:%.*]]
 ; CHECK:       exit:
-; CHECK-NEXT:    ret i1 [[CMP]]
+; CHECK-NEXT:    ret i1 true
 ;
 entry:
   %urem = urem i32 %a, 30
@@ -949,9 +949,9 @@
 ; CHECK-NEXT:    [[CMP2:%.*]] = icmp sgt i32 [[SREM]], -30
 ; CHECK-NEXT:    br i1 undef, label [[EXIT1:%.*]], label [[EXIT2:%.*]]
 ; CHECK:       exit1:
-; CHECK-NEXT:    ret i1 [[CMP1]]
+; CHECK-NEXT:    ret i1 true
 ; CHECK:       exit2:
-; CHECK-NEXT:    ret i1 [[CMP2]]
+; CHECK-NEXT:    ret i1 true
 ;
 entry:
   %srem = srem i32 %a, 30
@@ -972,9 +972,9 @@
 ; CHECK-NEXT:    [[CMP2:%.*]] = icmp sgt i32 [[SREM]], -17459217
 ; CHECK-NEXT:    br i1 undef, label [[EXIT1:%.*]], label [[EXIT2:%.*]]
 ; CHECK:       exit1:
-; CHECK-NEXT:    ret i1 [[CMP1]]
+; CHECK-NEXT:    ret i1 true
 ; CHECK:       exit2:
-; CHECK-NEXT:    ret i1 [[CMP2]]
+; CHECK-NEXT:    ret i1 true
 ;
 entry:
   %srem = sdiv i32 %a, 123
Index: llvm/lib/IR/ConstantRange.cpp
===================================================================
--- llvm/lib/IR/ConstantRange.cpp
+++ llvm/lib/IR/ConstantRange.cpp
@@ -790,8 +790,7 @@
   case Instruction::FMul:
     return multiply(Other);
   default:
-    // Conservatively return getFull set.
-    return getFull();
+    llvm_unreachable("Unsupported binary op");
   }
 }
 
Index: llvm/lib/Analysis/LazyValueInfo.cpp
===================================================================
--- llvm/lib/Analysis/LazyValueInfo.cpp
+++ llvm/lib/Analysis/LazyValueInfo.cpp
@@ -1082,31 +1082,18 @@
 
   assert(BO->getOperand(0)->getType()->isSized() &&
          "all operands to binary operators are sized");
-
-  // Filter out operators we don't know how to reason about before attempting to
-  // recurse on our operand(s).  This can cut a long search short if we know
-  // we're not going to be able to get any useful information anyways.
-  switch (BO->getOpcode()) {
-  case Instruction::Add:
-  case Instruction::Sub:
-  case Instruction::Mul:
-  case Instruction::UDiv:
-  case Instruction::Shl:
-  case Instruction::LShr:
-  case Instruction::AShr:
-  case Instruction::And:
-  case Instruction::Or:
-    return solveBlockValueBinaryOpImpl(BBLV, BO, BB,
-        [BO](const ConstantRange &CR1, const ConstantRange &CR2) {
-          return CR1.binaryOp(BO->getOpcode(), CR2);
-        });
-  default:
-    // Unhandled instructions are overdefined.
+  if (BO->getOpcode() == Instruction::Xor) {
+    // Xor is the only operation not supported by ConstantRange::binaryOp().
     LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()
                       << "' - overdefined (unknown binary operator).\n");
     BBLV = ValueLatticeElement::getOverdefined();
     return true;
-  };
+  }
+
+  return solveBlockValueBinaryOpImpl(BBLV, BO, BB,
+      [BO](const ConstantRange &CR1, const ConstantRange &CR2) {
+        return CR1.binaryOp(BO->getOpcode(), CR2);
+      });
 }
 
 bool LazyValueInfoImpl::solveBlockValueOverflowIntrinsic(


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