From 73a92c26ed012f70d90b042ef5c06baa83547b82 Mon Sep 17 00:00:00 2001
From: Valentijn van de Beek <valentijn.vandebeek@amd.com>
Date: Fri, 14 Jun 2024 12:33:16 +0100
Subject: [PATCH] [GISel][CombinerHelper] Shuffle pattern for reversing vector
 order

---
 .../lib/CodeGen/GlobalISel/CombinerHelper.cpp |  44 +++++
 .../prelegalizercombiner-shufflevector.mir    | 168 ++++++++++++++++++
 2 files changed, 212 insertions(+)

diff --git a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
index 2c77dcaa9f34..7b1558a3d7e8 100644
--- a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
@@ -494,6 +494,50 @@ bool CombinerHelper::tryCombineShuffleVector(MachineInstr &MI) {
     return true;
   }
 
+  // {n/2, n/2+1, ..., n, 0, 1, ..., n/2-1}
+  GeneratorType FirstHalf = adderGenerator(0, SrcNumElts / 2, 1);
+  GeneratorType SecondHalf = adderGenerator(SrcNumElts / 2, SrcNumElts, 1);
+  GeneratorType Reverse =
+      concatGenerators(SmallVector<GeneratorType>{FirstHalf, SecondHalf});
+
+  if (matchCombineShuffleVector(MI, Reverse, SrcNumElts)) {
+    // The shuffle is concatenating multiple vectors together.
+    // Collect the different operands for that.
+    Register UndefReg;
+    const Register Src1 = MI.getOperand(1).getReg();
+    const Register Src2 = MI.getOperand(2).getReg();
+    const ArrayRef<int> Mask = MI.getOperand(3).getShuffleMask();
+
+    // The destination can be longer than the source, so we separate them into
+    // equal blocks and check them separately to see if one of the blocks can be
+    // copied whole.
+    unsigned NumConcat = DstNumElts / SrcNumElts;
+    unsigned Index = 0;
+    for (unsigned Concat = 0; Concat < NumConcat; Concat++) {
+      unsigned Target = (Concat + 1) * SrcNumElts;
+      while (Index < Target) {
+        int MaskElt = Mask[Index];
+        if (MaskElt >= 0) {
+          Ops.push_back((MaskElt < (int)SrcNumElts) ? Src1 : Src2);
+          break;
+        }
+        Index++;
+      }
+
+      if (Index == Target) {
+        if (!UndefReg) {
+          Builder.setInsertPt(*MI.getParent(), MI);
+          UndefReg = Builder.buildUndef(SrcTy).getReg(0);
+        }
+        Ops.push_back(UndefReg);
+      }
+
+      Index = Target;
+    }
+    applyCombineShuffleVector(MI, {Ops[1], Ops[0]});
+    return true;
+  }
+
   return false;
 }
 
diff --git a/llvm/test/CodeGen/AIE/aie2/GlobalISel/prelegalizercombiner-shufflevector.mir b/llvm/test/CodeGen/AIE/aie2/GlobalISel/prelegalizercombiner-shufflevector.mir
index cb257d6a9fa4..79298703c50c 100644
--- a/llvm/test/CodeGen/AIE/aie2/GlobalISel/prelegalizercombiner-shufflevector.mir
+++ b/llvm/test/CodeGen/AIE/aie2/GlobalISel/prelegalizercombiner-shufflevector.mir
@@ -474,3 +474,171 @@ body:             |
     %2:_(<128 x s8>) = COPY $y3
     %3:_(<128 x s8>) = G_SHUFFLE_VECTOR %1:_(<128 x s8>), %2:_(<128 x s8>), shufflemask(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191)
     PseudoRET implicit $lr, implicit %3
+...
+
+---
+name:            concat_vector_reverse_32_512
+legalized:       false
+body:             |
+  bb.1.entry:
+    liveins: $wl2, $wl4
+    ; CHECK-LABEL: name: concat_vector_reverse_32_512
+    ; CHECK: liveins: $wl2, $wl4
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(<8 x s32>) = COPY $wl2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(<8 x s32>) = COPY $wl4
+    ; CHECK-NEXT: [[CONCAT_VECTORS:%[0-9]+]]:_(<16 x s32>) = G_CONCAT_VECTORS [[COPY1]](<8 x s32>), [[COPY]](<8 x s32>)
+    ; CHECK-NEXT: $x0 = COPY [[CONCAT_VECTORS]](<16 x s32>)
+    ; CHECK-NEXT: PseudoRET implicit $lr, implicit $x0
+    %1:_(<8 x s32>) = COPY $wl2
+    %2:_(<8 x s32>) = COPY $wl4
+    %0:_(<16 x s32>) = G_SHUFFLE_VECTOR %1:_(<8 x s32>), %2:_, shufflemask(8, 9, 10, 11, 12, 13, 14, 15, 0, 1, 2, 3, 4, 5, 6, 7)
+    $x0 = COPY %0:_(<16 x s32>)
+    PseudoRET implicit $lr, implicit $x0
+...
+
+---
+name:            concat_vector_reverse_32_512_undef_start_first
+legalized:       false
+body:             |
+  bb.1.entry:
+    liveins: $wl2, $wl4
+    ; CHECK-LABEL: name: concat_vector_reverse_32_512_undef_start_first
+    ; CHECK: liveins: $wl2, $wl4
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(<8 x s32>) = COPY $wl2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(<8 x s32>) = COPY $wl4
+    ; CHECK-NEXT: [[CONCAT_VECTORS:%[0-9]+]]:_(<16 x s32>) = G_CONCAT_VECTORS [[COPY1]](<8 x s32>), [[COPY]](<8 x s32>)
+    ; CHECK-NEXT: $x0 = COPY [[CONCAT_VECTORS]](<16 x s32>)
+    ; CHECK-NEXT: PseudoRET implicit $lr, implicit $x0
+    %1:_(<8 x s32>) = COPY $wl2
+    %2:_(<8 x s32>) = COPY $wl4
+    %0:_(<16 x s32>) = G_SHUFFLE_VECTOR %1:_(<8 x s32>), %2:_, shufflemask(-1, -1, -1, -1, 12, 13, 14, 15, 0, 1, 2, 3, 4, 5, 6, 7)
+    $x0 = COPY %0:_(<16 x s32>)
+    PseudoRET implicit $lr, implicit $x0
+...
+
+---
+name:            concat_vector_reverse_32_512_start_end
+legalized:       false
+body:             |
+  bb.1.entry:
+    liveins: $wl2, $wl4
+    ; CHECK-LABEL: name: concat_vector_reverse_32_512_start_end
+    ; CHECK: liveins: $wl2, $wl4
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(<8 x s32>) = COPY $wl2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(<8 x s32>) = COPY $wl4
+    ; CHECK-NEXT: [[CONCAT_VECTORS:%[0-9]+]]:_(<16 x s32>) = G_CONCAT_VECTORS [[COPY1]](<8 x s32>), [[COPY]](<8 x s32>)
+    ; CHECK-NEXT: $x0 = COPY [[CONCAT_VECTORS]](<16 x s32>)
+    ; CHECK-NEXT: PseudoRET implicit $lr, implicit $x0
+    %1:_(<8 x s32>) = COPY $wl2
+    %2:_(<8 x s32>) = COPY $wl4
+    %0:_(<16 x s32>) = G_SHUFFLE_VECTOR %1:_(<8 x s32>), %2:_, shufflemask(8, 9, 10, 11, 12, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7)
+    $x0 = COPY %0:_(<16 x s32>)
+    PseudoRET implicit $lr, implicit $x0
+...
+
+---
+name:            concat_vector_reverse_32_512_end_start
+legalized:       false
+body:             |
+  bb.1.entry:
+    liveins: $wl2, $wl4
+    ; CHECK-LABEL: name: concat_vector_reverse_32_512_end_start
+    ; CHECK: liveins: $wl2, $wl4
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(<8 x s32>) = COPY $wl2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(<8 x s32>) = COPY $wl4
+    ; CHECK-NEXT: [[CONCAT_VECTORS:%[0-9]+]]:_(<16 x s32>) = G_CONCAT_VECTORS [[COPY1]](<8 x s32>), [[COPY]](<8 x s32>)
+    ; CHECK-NEXT: $x0 = COPY [[CONCAT_VECTORS]](<16 x s32>)
+    ; CHECK-NEXT: PseudoRET implicit $lr, implicit $x0
+    %1:_(<8 x s32>) = COPY $wl2
+    %2:_(<8 x s32>) = COPY $wl4
+    %0:_(<16 x s32>) = G_SHUFFLE_VECTOR %1:_(<8 x s32>), %2:_, shufflemask(8, 9, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, 4, 5, 6, 7)
+    $x0 = COPY %0:_(<16 x s32>)
+    PseudoRET implicit $lr, implicit $x0
+...
+
+---
+name:            concat_vector_reverse_32_512_end_end
+legalized:       false
+body:             |
+  bb.1.entry:
+    liveins: $wl2, $wl4
+    ; CHECK-LABEL: name: concat_vector_reverse_32_512_end_end
+    ; CHECK: liveins: $wl2, $wl4
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(<8 x s32>) = COPY $wl2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(<8 x s32>) = COPY $wl4
+    ; CHECK-NEXT: [[CONCAT_VECTORS:%[0-9]+]]:_(<16 x s32>) = G_CONCAT_VECTORS [[COPY1]](<8 x s32>), [[COPY]](<8 x s32>)
+    ; CHECK-NEXT: $x0 = COPY [[CONCAT_VECTORS]](<16 x s32>)
+    ; CHECK-NEXT: PseudoRET implicit $lr, implicit $x0
+    %1:_(<8 x s32>) = COPY $wl2
+    %2:_(<8 x s32>) = COPY $wl4
+    %0:_(<16 x s32>) = G_SHUFFLE_VECTOR %1:_(<8 x s32>), %2:_, shufflemask(8, 9, 10, 11, 12, 13, 14, 15, 0, 1, 2, 3, -1, -1, -1, -1)
+    $x0 = COPY %0:_(<16 x s32>)
+    PseudoRET implicit $lr, implicit $x0
+...
+
+---
+name:            concat_vector_reverse_32_512_first_block
+legalized:       false
+body:             |
+  bb.1.entry:
+    liveins: $wl2, $wl4
+    ; CHECK-LABEL: name: concat_vector_reverse_32_512_first_block
+    ; CHECK: liveins: $wl2, $wl4
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(<8 x s32>) = COPY $wl2
+    ; CHECK-NEXT: [[DEF:%[0-9]+]]:_(<8 x s32>) = G_IMPLICIT_DEF
+    ; CHECK-NEXT: [[CONCAT_VECTORS:%[0-9]+]]:_(<16 x s32>) = G_CONCAT_VECTORS [[DEF]](<8 x s32>), [[COPY]](<8 x s32>)
+    ; CHECK-NEXT: $x0 = COPY [[CONCAT_VECTORS]](<16 x s32>)
+    ; CHECK-NEXT: PseudoRET implicit $lr, implicit $x0
+    %1:_(<8 x s32>) = COPY $wl2
+    %2:_(<8 x s32>) = COPY $wl4
+    %0:_(<16 x s32>) = G_SHUFFLE_VECTOR %1:_(<8 x s32>), %2:_, shufflemask(-1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7)
+    $x0 = COPY %0:_(<16 x s32>)
+    PseudoRET implicit $lr, implicit $x0
+...
+
+---
+name:            concat_vector_reverse_32_512_second_block
+legalized:       false
+body:             |
+  bb.1.entry:
+    liveins: $wl2, $wl4
+    ; CHECK-LABEL: name: concat_vector_reverse_32_512_second_block
+    ; CHECK: liveins: $wl2, $wl4
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(<8 x s32>) = COPY $wl4
+    ; CHECK-NEXT: [[DEF:%[0-9]+]]:_(<8 x s32>) = G_IMPLICIT_DEF
+    ; CHECK-NEXT: [[CONCAT_VECTORS:%[0-9]+]]:_(<16 x s32>) = G_CONCAT_VECTORS [[COPY]](<8 x s32>), [[DEF]](<8 x s32>)
+    ; CHECK-NEXT: $x0 = COPY [[CONCAT_VECTORS]](<16 x s32>)
+    ; CHECK-NEXT: PseudoRET implicit $lr, implicit $x0
+    %1:_(<8 x s32>) = COPY $wl2
+    %2:_(<8 x s32>) = COPY $wl4
+    %0:_(<16 x s32>) = G_SHUFFLE_VECTOR %1:_(<8 x s32>), %2:_, shufflemask(8, 9, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1)
+    $x0 = COPY %0:_(<16 x s32>)
+    PseudoRET implicit $lr, implicit $x0
+...
+
+---
+name:            concat_vector_reverse_32_512_random
+legalized:       false
+body:             |
+  bb.1.entry:
+    liveins: $wl2, $wl4
+    ; CHECK-LABEL: name: concat_vector_reverse_32_512_random
+    ; CHECK: liveins: $wl2, $wl4
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(<8 x s32>) = COPY $wl2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(<8 x s32>) = COPY $wl4
+    ; CHECK-NEXT: [[CONCAT_VECTORS:%[0-9]+]]:_(<16 x s32>) = G_CONCAT_VECTORS [[COPY1]](<8 x s32>), [[COPY]](<8 x s32>)
+    ; CHECK-NEXT: $x0 = COPY [[CONCAT_VECTORS]](<16 x s32>)
+    ; CHECK-NEXT: PseudoRET implicit $lr, implicit $x0
+    %1:_(<8 x s32>) = COPY $wl2
+    %2:_(<8 x s32>) = COPY $wl4
+    %0:_(<16 x s32>) = G_SHUFFLE_VECTOR %1:_(<8 x s32>), %2:_, shufflemask(8, 9, -1, 11, 12, 13, -1, 15, 0, 1, -1, 3, 4, 5, -1, 7)
+    $x0 = COPY %0:_(<16 x s32>)
+    PseudoRET implicit $lr, implicit $x0
\ No newline at end of file