[llvm] [LoongArch] Always try to widen vectors at the beginning of lowerVECTOR_SHUFFLE_XVPERMI (PR #164219)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-loongarch

Author: Zhaoxin Yang (ylzsx)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/164219.diff


2 Files Affected:

- (modified) llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp (+6) 
- (modified) llvm/test/CodeGen/LoongArch/lasx/shuffle-as-permute-and-shuffle.ll (+3-9) 


``````````diff
diff --git a/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
index f7deeafc9ccfc..21e8179a304ef 100644
--- a/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
+++ b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
@@ -2103,6 +2103,12 @@ static SDValue
 lowerVECTOR_SHUFFLE_XVPERMI(const SDLoc &DL, ArrayRef<int> Mask, MVT VT,
                             SDValue V1, SelectionDAG &DAG,
                             const LoongArchSubtarget &Subtarget) {
+  // Before selecting XVPERMI_D, always try to widen vectors to gain more
+  // optimization opportunities.
+  if (SDValue NewShuffle = widenShuffleMask(
+          DL, Mask, VT, V1, DAG.getUNDEF(V1.getValueType()), DAG))
+    return NewShuffle;
+
   // Only consider XVPERMI_D.
   if (Mask.size() != 4 || (VT != MVT::v4i64 && VT != MVT::v4f64))
     return SDValue();
diff --git a/llvm/test/CodeGen/LoongArch/lasx/shuffle-as-permute-and-shuffle.ll b/llvm/test/CodeGen/LoongArch/lasx/shuffle-as-permute-and-shuffle.ll
index 245f76472b844..7149cdb99063a 100644
--- a/llvm/test/CodeGen/LoongArch/lasx/shuffle-as-permute-and-shuffle.ll
+++ b/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

``````````

</details>


https://github.com/llvm/llvm-project/pull/164219