[llvm] [KnownBits] Add fast path for udiv by pow2 and overloads for shift ops by constant (PR #189779)

[via llvm-commits]

github-actions[bot] wrote:

<!--LLVM CODE FORMAT COMMENT: {clang-format}-->


:warning: C/C++ code formatter, clang-format found issues in your code. :warning:

<details>
<summary>
You can test this locally with the following command:
</summary>

``````````bash
git-clang-format --diff origin/main HEAD --extensions cpp,h -- llvm/include/llvm/Support/KnownBits.h llvm/lib/Support/KnownBits.cpp llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp --diff_from_common_commit
``````````

:warning:
The reproduction instructions above might return results for more than one PR
in a stack if you are using a stacked PR workflow. You can limit the results by
changing `origin/main` to the base branch/commit you want to compare against.
:warning:

</details>

<details>
<summary>
View the diff from clang-format here.
</summary>

``````````diff
diff --git a/llvm/lib/Support/KnownBits.cpp b/llvm/lib/Support/KnownBits.cpp
index 5748dfb21..8c58ef1db 100644
--- a/llvm/lib/Support/KnownBits.cpp
+++ b/llvm/lib/Support/KnownBits.cpp
@@ -404,8 +404,8 @@ static unsigned getMaxShiftAmount(const APInt &MaxValue, unsigned BitWidth) {
   return MaxValue.getLimitedValue(BitWidth - 1);
 }
 
-KnownBits KnownBits::shl(const KnownBits &LHS, unsigned ShiftAmt,
-                         bool NUW, bool NSW) {
+KnownBits KnownBits::shl(const KnownBits &LHS, unsigned ShiftAmt, bool NUW,
+                         bool NSW) {
   // TODO: This is simple fallback to generic RHS-based shl.
   // Add a specialized constant-shift implementation with identical semantics.
   KnownBits RHS = KnownBits::makeConstant(APInt(LHS.getBitWidth(), ShiftAmt));
@@ -460,7 +460,7 @@ KnownBits KnownBits::shl(const KnownBits &LHS, const KnownBits &RHS, bool NUW,
         MaxShiftAmount,
         std::max(LHS.countMaxLeadingZeros(), LHS.countMaxLeadingOnes()) - 1);
 
-   // Fast path for common case where the shift amount is unknown.
+  // Fast path for common case where the shift amount is unknown.
   if (MinShiftAmount == 0 && MaxShiftAmount == BitWidth - 1 &&
       isPowerOf2_32(BitWidth)) {
     Known.Zero.setLowBits(LHS.countMinTrailingZeros());

``````````

</details>


https://github.com/llvm/llvm-project/pull/189779