[llvm] [Mips] Use APInt::isMask/isShiftedMask to simplify code. (PR #116582)

[Craig Topper via llvm-commits]

https://github.com/topperc created https://github.com/llvm/llvm-project/pull/116582

None

>From 9a17418fe59c4069e371608f23cca8f7a61a325c Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Sun, 17 Nov 2024 23:29:03 -0800
Subject: [PATCH] [Mips] Use APInt::isMask/isShiftedMask to simplify code.

---
 llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp b/llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp
index afb027a533d5a6..c3e21e0ff7a0f0 100644
--- a/llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp
+++ b/llvm/lib/Target/Mips/MipsSEISelDAGToDAG.cpp
@@ -614,11 +614,9 @@ bool MipsSEDAGToDAGISel::selectVSplatMaskL(SDValue N, SDValue &Imm) const {
 
   if (selectVSplat(N.getNode(), ImmValue, EltTy.getSizeInBits()) &&
       ImmValue.getBitWidth() == EltTy.getSizeInBits()) {
-    // Extract the run of set bits starting with bit zero from the bitwise
-    // inverse of ImmValue, and test that the inverse of this is the same
-    // as the original value.
-    if (ImmValue == ~(~ImmValue & ~(~ImmValue + 1))) {
-
+    // Check if we have a leading one, then check if the whole value is a
+    // shifted mask.
+    if (ImmValue.isNegative() && ImmValue.isShiftedMask()) {
       Imm = CurDAG->getTargetConstant(ImmValue.popcount() - 1, SDLoc(N), EltTy);
       return true;
     }
@@ -647,9 +645,7 @@ bool MipsSEDAGToDAGISel::selectVSplatMaskR(SDValue N, SDValue &Imm) const {
 
   if (selectVSplat(N.getNode(), ImmValue, EltTy.getSizeInBits()) &&
       ImmValue.getBitWidth() == EltTy.getSizeInBits()) {
-    // Extract the run of set bits starting with bit zero, and test that the
-    // result is the same as the original value
-    if (ImmValue == (ImmValue & ~(ImmValue + 1))) {
+    if (ImmValue.isMask()) {
       Imm = CurDAG->getTargetConstant(ImmValue.popcount() - 1, SDLoc(N), EltTy);
       return true;
     }