[SCEV] Split out a helper function from isImpliedCond; NFC.

[sanjoy]

Summary

This helper routine will be used in a subsequent change.

[sanjoy]

• move a test case I had accidentally added to this change

[hfinkel]

LGTM.

include/llvm/Analysis/ScalarEvolution.h

private:
     /// Test whether the condition described by Pred, LHS, and RHS is true
     /// whenever the given FoundCondValue value evaluates to true.
     bool isImpliedCond(ICmpInst::Predicate Pred,
                        const SCEV *LHS, const SCEV *RHS,
                        Value *FoundCondValue,
                        bool Inverse);
 
     /// Test whether the condition described by Pred, LHS, and RHS is true
+    /// whenever the condition described by FoundPred, FoundLHS, FoundRHS is
+    /// true.
+    bool isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS,
+                       const SCEV *RHS, ICmpInst::Predicate FoundPred,
+                       const SCEV *FoundLHS, const SCEV *FoundRHS);
+
+    /// Test whether the condition described by Pred, LHS, and RHS is true
     /// whenever the condition described by Pred, FoundLHS, and FoundRHS is
     /// true.
     bool isImpliedCondOperands(ICmpInst::Predicate Pred,
                                const SCEV *LHS, const SCEV *RHS,
                                const SCEV *FoundLHS, const SCEV *FoundRHS);
 
     /// Test whether the condition described by Pred, LHS, and RHS is true
     /// whenever the condition described by Pred, FoundLHS, and FoundRHS is

lib/Analysis/ScalarEvolution.cpp

bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred,
   if (Inverse)
     FoundPred = ICI->getInversePredicate();
   else
     FoundPred = ICI->getPredicate();
 
   const SCEV *FoundLHS = getSCEV(ICI->getOperand(0));
   const SCEV *FoundRHS = getSCEV(ICI->getOperand(1));
 
+  return isImpliedCond(Pred, LHS, RHS, FoundPred, FoundLHS, FoundRHS);
+}
+
+bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, const SCEV *LHS,
+                                    const SCEV *RHS,
+                                    ICmpInst::Predicate FoundPred,
+                                    const SCEV *FoundLHS,
+                                    const SCEV *FoundRHS) {
   // Balance the types.
   if (getTypeSizeInBits(LHS->getType()) <
       getTypeSizeInBits(FoundLHS->getType())) {
     if (CmpInst::isSigned(Pred)) {
       LHS = getSignExtendExpr(LHS, FoundLHS->getType());
       RHS = getSignExtendExpr(RHS, FoundLHS->getType());
     } else {
       LHS = getZeroExtendExpr(LHS, FoundLHS->getType());

test/Transforms/IndVarSimplify/eliminate-comparison.ll

be:
   call void @side_effect()
   %be.cond = icmp slt i32 %iv, %len.sub.1
   br i1 %be.cond, label %loop, label %leave
 
  leave:
   ret void
 }
 
+define void @func_15(i32* %len.ptr) {
+; CHECK-LABEL: @func_15(
+ entry:
+  %len = load i32, i32* %len.ptr, !range !0
+  %len.add.1 = add i32 %len, 1
+  %len.add.1.is.zero = icmp eq i32 %len.add.1, 0
+  br i1 %len.add.1.is.zero, label %leave, label %loop
+
+ loop:
+; CHECK: loop:
+  %iv = phi i32 [ 0, %entry ], [ %iv.inc, %be ]
+  call void @side_effect()
+  %iv.inc = add i32 %iv, 1
+  %iv.cmp = icmp ult i32 %iv, %len.add.1
+  br i1 %iv.cmp, label %be, label %leave
+; CHECK: br i1 true, label %be, label %leave
+
+ be:
+  call void @side_effect()
+  %be.cond = icmp ult i32 %iv, %len
+  br i1 %be.cond, label %loop, label %leave
+
+ leave:
+  ret void
+}
+
 !0 = !{i32 0, i32 2147483647}
+