[ValueTracking] Remove SPF support from `computeKnownBitsFromOperator` (#76630)

This patch removes redundant SPF support
(https://github.com/llvm/llvm-project/commit/5350e1b5096aa4707aa525baf7398d93b4a4f1a5)
from `computeKnownBitsFromOperator` as we always canonicalize a SPF into
an intrinsic call.

Compile-time improvement:
http://llvm-compile-time-tracker.com/compare.php?from=3dc0638cfc19e140daff7bf1281648daca8212fa&to=8771ef0749fb2ba4304dc68d418c88ec5769346f&stat=instructions:u

|stage1-O3|stage1-ReleaseThinLTO|stage1-ReleaseLTO-g|stage1-O0-g|stage2-O3|stage2-O0-g|stage2-clang|
|--|--|--|--|--|--|--|
-0.01%|-0.01%|+0.01%|+0.00%|+0.01%|+0.04%|-0.01%|

1 files changed, 0 insertions, 34 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index cac2602..16d78c1 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -983,45 +983,11 @@ static void computeKnownBitsFromOperator(const Operator *I,
     break;
   }
   case Instruction::Select: {
-    const Value *LHS = nullptr, *RHS = nullptr;
-    SelectPatternFlavor SPF = matchSelectPattern(I, LHS, RHS).Flavor;
-    if (SelectPatternResult::isMinOrMax(SPF)) {
-      computeKnownBits(RHS, Known, Depth + 1, Q);
-      computeKnownBits(LHS, Known2, Depth + 1, Q);
-      switch (SPF) {
-      default:
-        llvm_unreachable("Unhandled select pattern flavor!");
-      case SPF_SMAX:
-        Known = KnownBits::smax(Known, Known2);
-        break;
-      case SPF_SMIN:
-        Known = KnownBits::smin(Known, Known2);
-        break;
-      case SPF_UMAX:
-        Known = KnownBits::umax(Known, Known2);
-        break;
-      case SPF_UMIN:
-        Known = KnownBits::umin(Known, Known2);
-        break;
-      }
-      break;
-    }
-
     computeKnownBits(I->getOperand(2), Known, Depth + 1, Q);
     computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);
 
     // Only known if known in both the LHS and RHS.
     Known = Known.intersectWith(Known2);
-
-    if (SPF == SPF_ABS) {
-      // RHS from matchSelectPattern returns the negation part of abs pattern.
-      // If the negate has an NSW flag we can assume the sign bit of the result
-      // will be 0 because that makes abs(INT_MIN) undefined.
-      if (match(RHS, m_Neg(m_Specific(LHS))) &&
-          Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(RHS)))
-        Known.Zero.setSignBit();
-    }
-
     break;
   }
   case Instruction::FPTrunc: