[ConstantFolding] Added ilogb in isMathLibCallNoop()

ilogb libcall was not being constant folded correctly.
This patch adds ilogb with its correct domain in isMathLibCallNoop().

Fixes #101873

Author: kshitijvp

llvm/lib/Analysis/ConstantFolding.cpp

@@ -3806,7 +3806,8 @@ bool llvm::isMathLibCallNoop(const CallBase *Call,
       case LibFunc_log10:
       case LibFunc_log10f:
         return Op.isNaN() || (!Op.isZero() && !Op.isNegative());
-
+      case LibFunc_ilogb:
+        return !(Op.isNaN()) && !(Op.isZero() || Op.isInfinity());
       case LibFunc_expl:
       case LibFunc_exp:
       case LibFunc_expf:

llvm/lib/Transforms/Utils/LibCallsShrinkWrap.cpp

@@ -246,7 +246,6 @@ bool LibCallsShrinkWrap::performCallErrors(CallInst *CI,
   case LibFunc_logb:   // Same as log
   case LibFunc_logbf:  // Same as log
   case LibFunc_logbl:  // Same as log
-  case LibFunc_ilogb:  // Same as log
   {
     ++NumWrappedOneCond;
     Cond = createCond(CI, CmpInst::FCMP_OLE, 0.0f);

llvm/test/Transforms/Util/libcalls-shrinkwrap-float.ll

@@ -334,6 +334,8 @@ entry:
 ; CHECK-NEXT: %call_11 = call float @log1pf(float %value)
 ; CHECK-NEXT: br label %[[END_LABEL]]
 ; CHECK: [[END_LABEL]]:
+
+  %call_12 = call i32 @ilogb(float %value) strictfp
   ret void
 }