[llvm] 059d90d - [Legalizer] Cache extracted element when lowering G_SHUFFLE_VECTOR. (#163893)

via llvm-commits llvm-commits at lists.llvm.org
Sat Oct 25 08:26:15 PDT 2025 

Author: Yunqing Yu
Date: 2025-10-25T10:26:11-05:00
New Revision: 059d90d08f610d5919c42646f267bbab77f7bee4

URL: https://github.com/llvm/llvm-project/commit/059d90d08f610d5919c42646f267bbab77f7bee4
DIFF: https://github.com/llvm/llvm-project/commit/059d90d08f610d5919c42646f267bbab77f7bee4.diff

LOG: [Legalizer] Cache extracted element when lowering G_SHUFFLE_VECTOR. (#163893)

Cache extracted elements in lowerShuffleVector(). For example, when
lowering
```
%0:_(<2 x s32>) = G_BUILD_VECTOR %0, %1
%2:_(<N x s32>) = G_SHUFFLE_VECTOR %1, shufflemask(0, 0, 0, 0 ... x N )
```
Currently, we generate `N` `G_EXTRACT_VECTOR_ELT` for each element in
shufflemask. This is undesirable and bloats the code, especially for
larger vectors.

With this change, we only generate one `G_EXTRACT_VECTOR_ELT` from `%0`
and reuse it for all four result elements.

Added: 
    

Modified: 
    llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
    llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-shuffle-vector.mir
    llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-shuffle-vector.s16.mir

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 178529f2bee05..52c43a4ac4a04 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -9084,6 +9084,8 @@ LegalizerHelper::lowerShuffleVector(MachineInstr &MI) {
   SmallVector<Register, 32> BuildVec;
   LLT EltTy = DstTy.getScalarType();
 
+  DenseMap<unsigned, Register> CachedExtract;
+
   for (int Idx : Mask) {
     if (Idx < 0) {
       if (!Undef.isValid())
@@ -9097,9 +9099,13 @@ LegalizerHelper::lowerShuffleVector(MachineInstr &MI) {
     int NumElts = Src0Ty.getNumElements();
     Register SrcVec = Idx < NumElts ? Src0Reg : Src1Reg;
     int ExtractIdx = Idx < NumElts ? Idx : Idx - NumElts;
-    auto IdxK = MIRBuilder.buildConstant(IdxTy, ExtractIdx);
-    auto Extract = MIRBuilder.buildExtractVectorElement(EltTy, SrcVec, IdxK);
-    BuildVec.push_back(Extract.getReg(0));
+    auto [It, Inserted] = CachedExtract.try_emplace(Idx);
+    if (Inserted) {
+      auto IdxK = MIRBuilder.buildConstant(IdxTy, ExtractIdx);
+      It->second =
+          MIRBuilder.buildExtractVectorElement(EltTy, SrcVec, IdxK).getReg(0);
+    }
+    BuildVec.push_back(It->second);
   }
 
   assert(DstTy.isVector() && "Unexpected scalar G_SHUFFLE_VECTOR");

diff  --git a/llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-shuffle-vector.mir b/llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-shuffle-vector.mir
index 423ce8219ecba..d5947c829f192 100644
--- a/llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-shuffle-vector.mir
+++ b/llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-shuffle-vector.mir
@@ -90,9 +90,7 @@ body: |
     ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(<2 x s32>) = COPY $vgpr2_vgpr3
     ; CHECK-NEXT: [[UV:%[0-9]+]]:_(s32), [[UV1:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[COPY]](<2 x s32>)
     ; CHECK-NEXT: [[COPY2:%[0-9]+]]:_(s32) = COPY [[UV]](s32)
-    ; CHECK-NEXT: [[UV2:%[0-9]+]]:_(s32), [[UV3:%[0-9]+]]:_(s32) = G_UNMERGE_VALUES [[COPY]](<2 x s32>)
-    ; CHECK-NEXT: [[COPY3:%[0-9]+]]:_(s32) = COPY [[UV2]](s32)
-    ; CHECK-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s32>) = G_BUILD_VECTOR [[COPY2]](s32), [[COPY3]](s32)
+    ; CHECK-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s32>) = G_BUILD_VECTOR [[COPY2]](s32), [[COPY2]](s32)
     ; CHECK-NEXT: $vgpr0_vgpr1 = COPY [[BUILD_VECTOR]](<2 x s32>)
     %0:_(<2 x s32>) = COPY $vgpr0_vgpr1
     %1:_(<2 x s32>) = COPY $vgpr2_vgpr3
@@ -328,3 +326,30 @@ body: |
     $vgpr0_vgpr1 = COPY %4
 
 ...
+
+---
+name: shufflevector_cache_element
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+    liveins: $vgpr0_vgpr1, $vgpr2_vgpr3
+
+    ; CHECK-LABEL: name: shufflevector_cache_element
+    ; CHECK: liveins: $vgpr0_vgpr1, $vgpr2_vgpr3
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK-NEXT: [[COPY2:%[0-9]+]]:_(s32) = COPY [[COPY]](s32)
+    ; CHECK-NEXT: [[COPY3:%[0-9]+]]:_(s32) = COPY [[COPY1]](s32)
+    ; CHECK-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<8 x s32>) = G_BUILD_VECTOR [[COPY2]](s32), [[COPY2]](s32), [[COPY2]](s32), [[COPY2]](s32), [[COPY3]](s32), [[COPY3]](s32), [[COPY3]](s32), [[COPY3]](s32)
+    ; CHECK-NEXT: [[EVEC:%[0-9]+]]:_(s32) = G_EXTRACT_VECTOR_ELT [[BUILD_VECTOR]](<8 x s32>), [[COPY1]](s32)
+    ; CHECK-NEXT: $vgpr0 = COPY [[EVEC]](s32)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(<2 x s32>) = G_BUILD_VECTOR %0, %1
+    %3:_(<8 x s32>) = G_SHUFFLE_VECTOR %2, %2, shufflemask(0, 0, 0, 0, 3, 3, 3, 3)
+    %4:_(s32) = G_EXTRACT_VECTOR_ELT %3(<8 x s32>), %1(s32)
+    $vgpr0 = COPY %4
+
+...

diff  --git a/llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-shuffle-vector.s16.mir b/llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-shuffle-vector.s16.mir
index 10f425c96e6f4..dff8111de72d9 100644
--- a/llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-shuffle-vector.s16.mir
+++ b/llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-shuffle-vector.s16.mir
@@ -237,16 +237,13 @@ body: |
     ; GFX8-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
     ; GFX8-NEXT: [[BITCAST:%[0-9]+]]:_(s32) = G_BITCAST [[COPY]](<2 x s16>)
     ; GFX8-NEXT: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST]], [[C]](s32)
-    ; GFX8-NEXT: [[BITCAST1:%[0-9]+]]:_(s32) = G_BITCAST [[COPY]](<2 x s16>)
-    ; GFX8-NEXT: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST1]], [[C]](s32)
     ; GFX8-NEXT: [[C1:%[0-9]+]]:_(s32) = G_CONSTANT i32 65535
     ; GFX8-NEXT: [[AND:%[0-9]+]]:_(s32) = G_AND [[LSHR]], [[C1]]
-    ; GFX8-NEXT: [[AND1:%[0-9]+]]:_(s32) = G_AND [[LSHR1]], [[C1]]
     ; GFX8-NEXT: [[C2:%[0-9]+]]:_(s32) = G_CONSTANT i32 16
-    ; GFX8-NEXT: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[AND1]], [[C2]](s32)
+    ; GFX8-NEXT: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[AND]], [[C2]](s32)
     ; GFX8-NEXT: [[OR:%[0-9]+]]:_(s32) = G_OR [[AND]], [[SHL]]
-    ; GFX8-NEXT: [[BITCAST2:%[0-9]+]]:_(<2 x s16>) = G_BITCAST [[OR]](s32)
-    ; GFX8-NEXT: $vgpr0 = COPY [[BITCAST2]](<2 x s16>)
+    ; GFX8-NEXT: [[BITCAST1:%[0-9]+]]:_(<2 x s16>) = G_BITCAST [[OR]](s32)
+    ; GFX8-NEXT: $vgpr0 = COPY [[BITCAST1]](<2 x s16>)
     ;
     ; GFX9-LABEL: name: shufflevector_v2s16_v2s16_0_0
     ; GFX9: liveins: $vgpr0, $vgpr1
@@ -257,10 +254,7 @@ body: |
     ; GFX9-NEXT: [[BITCAST:%[0-9]+]]:_(s32) = G_BITCAST [[COPY]](<2 x s16>)
     ; GFX9-NEXT: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST]], [[C]](s32)
     ; GFX9-NEXT: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[LSHR]](s32)
-    ; GFX9-NEXT: [[BITCAST1:%[0-9]+]]:_(s32) = G_BITCAST [[COPY]](<2 x s16>)
-    ; GFX9-NEXT: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST1]], [[C]](s32)
-    ; GFX9-NEXT: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[LSHR1]](s32)
-    ; GFX9-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC1]](s16)
+    ; GFX9-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC]](s16)
     ; GFX9-NEXT: $vgpr0 = COPY [[BUILD_VECTOR]](<2 x s16>)
     %0:_(<2 x s16>) = COPY $vgpr0
     %1:_(<2 x s16>) = COPY $vgpr1
@@ -285,12 +279,10 @@ body: |
     ; GFX8-NEXT: [[BITCAST:%[0-9]+]]:_(s32) = G_BITCAST [[COPY]](<2 x s16>)
     ; GFX8-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 16
     ; GFX8-NEXT: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST]], [[C]](s32)
-    ; GFX8-NEXT: [[BITCAST1:%[0-9]+]]:_(s32) = G_BITCAST [[COPY]](<2 x s16>)
-    ; GFX8-NEXT: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST1]], [[C]](s32)
-    ; GFX8-NEXT: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[LSHR1]], [[C]](s32)
+    ; GFX8-NEXT: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[LSHR]], [[C]](s32)
     ; GFX8-NEXT: [[OR:%[0-9]+]]:_(s32) = G_OR [[LSHR]], [[SHL]]
-    ; GFX8-NEXT: [[BITCAST2:%[0-9]+]]:_(<2 x s16>) = G_BITCAST [[OR]](s32)
-    ; GFX8-NEXT: $vgpr0 = COPY [[BITCAST2]](<2 x s16>)
+    ; GFX8-NEXT: [[BITCAST1:%[0-9]+]]:_(<2 x s16>) = G_BITCAST [[OR]](s32)
+    ; GFX8-NEXT: $vgpr0 = COPY [[BITCAST1]](<2 x s16>)
     ;
     ; GFX9-LABEL: name: shufflevector_v2s16_v2s16_1_1
     ; GFX9: liveins: $vgpr0, $vgpr1
@@ -301,10 +293,7 @@ body: |
     ; GFX9-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 16
     ; GFX9-NEXT: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST]], [[C]](s32)
     ; GFX9-NEXT: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[LSHR]](s32)
-    ; GFX9-NEXT: [[BITCAST1:%[0-9]+]]:_(s32) = G_BITCAST [[COPY]](<2 x s16>)
-    ; GFX9-NEXT: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST1]], [[C]](s32)
-    ; GFX9-NEXT: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[LSHR1]](s32)
-    ; GFX9-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC1]](s16)
+    ; GFX9-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC]](s16)
     ; GFX9-NEXT: $vgpr0 = COPY [[BUILD_VECTOR]](<2 x s16>)
     %0:_(<2 x s16>) = COPY $vgpr0
     %1:_(<2 x s16>) = COPY $vgpr1
@@ -329,16 +318,13 @@ body: |
     ; GFX8-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
     ; GFX8-NEXT: [[BITCAST:%[0-9]+]]:_(s32) = G_BITCAST [[COPY1]](<2 x s16>)
     ; GFX8-NEXT: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST]], [[C]](s32)
-    ; GFX8-NEXT: [[BITCAST1:%[0-9]+]]:_(s32) = G_BITCAST [[COPY1]](<2 x s16>)
-    ; GFX8-NEXT: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST1]], [[C]](s32)
     ; GFX8-NEXT: [[C1:%[0-9]+]]:_(s32) = G_CONSTANT i32 65535
     ; GFX8-NEXT: [[AND:%[0-9]+]]:_(s32) = G_AND [[LSHR]], [[C1]]
-    ; GFX8-NEXT: [[AND1:%[0-9]+]]:_(s32) = G_AND [[LSHR1]], [[C1]]
     ; GFX8-NEXT: [[C2:%[0-9]+]]:_(s32) = G_CONSTANT i32 16
-    ; GFX8-NEXT: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[AND1]], [[C2]](s32)
+    ; GFX8-NEXT: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[AND]], [[C2]](s32)
     ; GFX8-NEXT: [[OR:%[0-9]+]]:_(s32) = G_OR [[AND]], [[SHL]]
-    ; GFX8-NEXT: [[BITCAST2:%[0-9]+]]:_(<2 x s16>) = G_BITCAST [[OR]](s32)
-    ; GFX8-NEXT: $vgpr0 = COPY [[BITCAST2]](<2 x s16>)
+    ; GFX8-NEXT: [[BITCAST1:%[0-9]+]]:_(<2 x s16>) = G_BITCAST [[OR]](s32)
+    ; GFX8-NEXT: $vgpr0 = COPY [[BITCAST1]](<2 x s16>)
     ;
     ; GFX9-LABEL: name: shufflevector_v2s16_v2s16_2_2
     ; GFX9: liveins: $vgpr0, $vgpr1
@@ -349,10 +335,7 @@ body: |
     ; GFX9-NEXT: [[BITCAST:%[0-9]+]]:_(s32) = G_BITCAST [[COPY1]](<2 x s16>)
     ; GFX9-NEXT: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST]], [[C]](s32)
     ; GFX9-NEXT: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[LSHR]](s32)
-    ; GFX9-NEXT: [[BITCAST1:%[0-9]+]]:_(s32) = G_BITCAST [[COPY1]](<2 x s16>)
-    ; GFX9-NEXT: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST1]], [[C]](s32)
-    ; GFX9-NEXT: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[LSHR1]](s32)
-    ; GFX9-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC1]](s16)
+    ; GFX9-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC]](s16)
     ; GFX9-NEXT: $vgpr0 = COPY [[BUILD_VECTOR]](<2 x s16>)
     %0:_(<2 x s16>) = COPY $vgpr0
     %1:_(<2 x s16>) = COPY $vgpr1
@@ -641,12 +624,10 @@ body: |
     ; GFX8-NEXT: [[BITCAST:%[0-9]+]]:_(s32) = G_BITCAST [[COPY1]](<2 x s16>)
     ; GFX8-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 16
     ; GFX8-NEXT: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST]], [[C]](s32)
-    ; GFX8-NEXT: [[BITCAST1:%[0-9]+]]:_(s32) = G_BITCAST [[COPY1]](<2 x s16>)
-    ; GFX8-NEXT: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST1]], [[C]](s32)
-    ; GFX8-NEXT: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[LSHR1]], [[C]](s32)
+    ; GFX8-NEXT: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[LSHR]], [[C]](s32)
     ; GFX8-NEXT: [[OR:%[0-9]+]]:_(s32) = G_OR [[LSHR]], [[SHL]]
-    ; GFX8-NEXT: [[BITCAST2:%[0-9]+]]:_(<2 x s16>) = G_BITCAST [[OR]](s32)
-    ; GFX8-NEXT: $vgpr0 = COPY [[BITCAST2]](<2 x s16>)
+    ; GFX8-NEXT: [[BITCAST1:%[0-9]+]]:_(<2 x s16>) = G_BITCAST [[OR]](s32)
+    ; GFX8-NEXT: $vgpr0 = COPY [[BITCAST1]](<2 x s16>)
     ;
     ; GFX9-LABEL: name: shufflevector_v2s16_v2s16_3_3
     ; GFX9: liveins: $vgpr0, $vgpr1
@@ -657,10 +638,7 @@ body: |
     ; GFX9-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 16
     ; GFX9-NEXT: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST]], [[C]](s32)
     ; GFX9-NEXT: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[LSHR]](s32)
-    ; GFX9-NEXT: [[BITCAST1:%[0-9]+]]:_(s32) = G_BITCAST [[COPY1]](<2 x s16>)
-    ; GFX9-NEXT: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST1]], [[C]](s32)
-    ; GFX9-NEXT: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[LSHR1]](s32)
-    ; GFX9-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC1]](s16)
+    ; GFX9-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC]](s16)
     ; GFX9-NEXT: $vgpr0 = COPY [[BUILD_VECTOR]](<2 x s16>)
     %0:_(<2 x s16>) = COPY $vgpr0
     %1:_(<2 x s16>) = COPY $vgpr1
@@ -733,16 +711,13 @@ body: |
     ; GFX8-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 0
     ; GFX8-NEXT: [[BITCAST:%[0-9]+]]:_(s32) = G_BITCAST [[COPY]](<2 x s16>)
     ; GFX8-NEXT: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST]], [[C]](s32)
-    ; GFX8-NEXT: [[BITCAST1:%[0-9]+]]:_(s32) = G_BITCAST [[COPY]](<2 x s16>)
-    ; GFX8-NEXT: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST1]], [[C]](s32)
     ; GFX8-NEXT: [[C1:%[0-9]+]]:_(s32) = G_CONSTANT i32 65535
     ; GFX8-NEXT: [[AND:%[0-9]+]]:_(s32) = G_AND [[LSHR]], [[C1]]
-    ; GFX8-NEXT: [[AND1:%[0-9]+]]:_(s32) = G_AND [[LSHR1]], [[C1]]
     ; GFX8-NEXT: [[C2:%[0-9]+]]:_(s32) = G_CONSTANT i32 16
-    ; GFX8-NEXT: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[AND1]], [[C2]](s32)
+    ; GFX8-NEXT: [[SHL:%[0-9]+]]:_(s32) = G_SHL [[AND]], [[C2]](s32)
     ; GFX8-NEXT: [[OR:%[0-9]+]]:_(s32) = G_OR [[AND]], [[SHL]]
-    ; GFX8-NEXT: [[BITCAST2:%[0-9]+]]:_(<2 x s16>) = G_BITCAST [[OR]](s32)
-    ; GFX8-NEXT: $vgpr0 = COPY [[BITCAST2]](<2 x s16>)
+    ; GFX8-NEXT: [[BITCAST1:%[0-9]+]]:_(<2 x s16>) = G_BITCAST [[OR]](s32)
+    ; GFX8-NEXT: $vgpr0 = COPY [[BITCAST1]](<2 x s16>)
     ;
     ; GFX9-LABEL: name: shufflevector_v2s16_v2s16_2_0
     ; GFX9: liveins: $vgpr0, $vgpr1
@@ -753,10 +728,7 @@ body: |
     ; GFX9-NEXT: [[BITCAST:%[0-9]+]]:_(s32) = G_BITCAST [[COPY]](<2 x s16>)
     ; GFX9-NEXT: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST]], [[C]](s32)
     ; GFX9-NEXT: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[LSHR]](s32)
-    ; GFX9-NEXT: [[BITCAST1:%[0-9]+]]:_(s32) = G_BITCAST [[COPY]](<2 x s16>)
-    ; GFX9-NEXT: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[BITCAST1]], [[C]](s32)
-    ; GFX9-NEXT: [[TRUNC1:%[0-9]+]]:_(s16) = G_TRUNC [[LSHR1]](s32)
-    ; GFX9-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC1]](s16)
+    ; GFX9-NEXT: [[BUILD_VECTOR:%[0-9]+]]:_(<2 x s16>) = G_BUILD_VECTOR [[TRUNC]](s16), [[TRUNC]](s16)
     ; GFX9-NEXT: $vgpr0 = COPY [[BUILD_VECTOR]](<2 x s16>)
     %0:_(<2 x s16>) = COPY $vgpr0
     %1:_(<2 x s16>) = COPY $vgpr1

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