[InstCombine] Canonicalize the fcmp range check idiom into fabs + fcmp (#76367)

This patch canonicalizes the fcmp range check idiom into `fabs + fcmp`
since the canonicalized form is better than the original form for the
backends.
Godbolt: https://godbolt.org/z/x3eqPb1fz
```
and (fcmp olt/ole/ult/ule x, C), (fcmp ogt/oge/ugt/uge x, -C) --> fabs(x) olt/ole/ult/ule C
or  (fcmp ogt/oge/ugt/uge x, C), (fcmp olt/ole/ult/ule x, -C) --> fabs(x) ogt/oge/ugt/uge C
```
Alive2: https://alive2.llvm.org/ce/z/MRtoYq

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

@@ -1419,6 +1419,44 @@ Value *InstCombinerImpl::foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS,
     }
   }
 
+  // Canonicalize the range check idiom:
+  // and (fcmp olt/ole/ult/ule x, C), (fcmp ogt/oge/ugt/uge x, -C)
+  // --> fabs(x) olt/ole/ult/ule C
+  // or  (fcmp ogt/oge/ugt/uge x, C), (fcmp olt/ole/ult/ule x, -C)
+  // --> fabs(x) ogt/oge/ugt/uge C
+  // TODO: Generalize to handle a negated variable operand?
+  const APFloat *LHSC, *RHSC;
+  if (LHS0 == RHS0 && LHS->hasOneUse() && RHS->hasOneUse() &&
+      FCmpInst::getSwappedPredicate(PredL) == PredR &&
+      match(LHS1, m_APFloatAllowUndef(LHSC)) &&
+      match(RHS1, m_APFloatAllowUndef(RHSC)) &&
+      LHSC->bitwiseIsEqual(neg(*RHSC))) {
+    auto IsLessThanOrLessEqual = [](FCmpInst::Predicate Pred) {
+      switch (Pred) {
+      case FCmpInst::FCMP_OLT:
+      case FCmpInst::FCMP_OLE:
+      case FCmpInst::FCMP_ULT:
+      case FCmpInst::FCMP_ULE:
+        return true;
+      default:
+        return false;
+      }
+    };
+    if (IsLessThanOrLessEqual(IsAnd ? PredR : PredL)) {
+      std::swap(LHSC, RHSC);
+      std::swap(PredL, PredR);
+    }
+    if (IsLessThanOrLessEqual(IsAnd ? PredL : PredR)) {
+      BuilderTy::FastMathFlagGuard Guard(Builder);
+      Builder.setFastMathFlags(LHS->getFastMathFlags() |
+                               RHS->getFastMathFlags());
+
+      Value *FAbs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, LHS0);
+      return Builder.CreateFCmp(PredL, FAbs,
+                                ConstantFP::get(LHS0->getType(), *LHSC));
+    }
+  }
+
   return nullptr;
 }