[LoongArch] Move widenShuffleMask before lowerVECTOR_SHUFFLE_XVPERMI to improve code quality (#164219)

Author: ylzsx

llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp

@@ -2614,6 +2614,9 @@ static SDValue lower256BitShuffle(const SDLoc &DL, ArrayRef<int> Mask, MVT VT,
     if ((Result = lowerVECTOR_SHUFFLE_XVSHUF4I(DL, Mask, VT, V1, V2, DAG,
                                                Subtarget)))
       return Result;
+    // Try to widen vectors to gain more optimization opportunities.
+    if (SDValue NewShuffle = widenShuffleMask(DL, Mask, VT, V1, V2, DAG))
+      return NewShuffle;
     if ((Result =
              lowerVECTOR_SHUFFLE_XVPERMI(DL, Mask, VT, V1, DAG, Subtarget)))
       return Result;

llvm/test/CodeGen/LoongArch/lasx/shuffle-as-permute-and-shuffle.ll

@@ -32,9 +32,7 @@ define <16 x i16> @shuffle_v16i16(<16 x i16> %a) {
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    pcalau12i $a0, %pc_hi20(.LCPI2_0)
 ; CHECK-NEXT:    xvld $xr1, $a0, %pc_lo12(.LCPI2_0)
-; CHECK-NEXT:    xvpermi.d $xr2, $xr0, 78
-; CHECK-NEXT:    xvshuf.w $xr1, $xr2, $xr0
-; CHECK-NEXT:    xvori.b $xr0, $xr1, 0
+; CHECK-NEXT:    xvperm.w $xr0, $xr0, $xr1
 ; CHECK-NEXT:    ret
   %shuffle = shufflevector <16 x i16> %a, <16 x i16> poison, <16 x i32> <i32 8, i32 9, i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>
   ret <16 x i16> %shuffle
@@ -55,9 +53,7 @@ define <16 x i16> @shuffle_v16i16_same_lane(<16 x i16> %a) {
 define <8 x i32> @shuffle_v8i32(<8 x i32> %a) {
 ; CHECK-LABEL: shuffle_v8i32:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    pcalau12i $a0, %pc_hi20(.LCPI4_0)
-; CHECK-NEXT:    xvld $xr1, $a0, %pc_lo12(.LCPI4_0)
-; CHECK-NEXT:    xvperm.w $xr0, $xr0, $xr1
+; CHECK-NEXT:    xvpermi.d $xr0, $xr0, 226
 ; CHECK-NEXT:    ret
   %shuffle = shufflevector <8 x i32> %a, <8 x i32> poison, <8 x i32> <i32 4, i32 5, i32 0, i32 1, i32 4, i32 5, i32 6, i32 7>
   ret <8 x i32> %shuffle
@@ -93,9 +89,7 @@ define <4 x i64> @shuffle_v4i64_same_lane(<4 x i64> %a) {
 define <8 x float> @shuffle_v8f32(<8 x float> %a) {
 ; CHECK-LABEL: shuffle_v8f32:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    pcalau12i $a0, %pc_hi20(.LCPI8_0)
-; CHECK-NEXT:    xvld $xr1, $a0, %pc_lo12(.LCPI8_0)
-; CHECK-NEXT:    xvperm.w $xr0, $xr0, $xr1
+; CHECK-NEXT:    xvpermi.d $xr0, $xr0, 226
 ; CHECK-NEXT:    ret
   %shuffle = shufflevector <8 x float> %a, <8 x float> poison, <8 x i32> <i32 4, i32 5, i32 0, i32 1, i32 4, i32 5, i32 6, i32 7>
   ret <8 x float> %shuffle