[PATCH] D64411: [AMDGPU] Simplify the exclusive scan used for optimized atomics

[Jay Foad via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL366543: [AMDGPU] Simplify the exclusive scan used for optimized atomics (authored by foad, committed by ).

Changed prior to commit:
  https://reviews.llvm.org/D64411?vs=208661&id=210771#toc

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D64411/new/

https://reviews.llvm.org/D64411

Files:
  llvm/trunk/lib/Target/AMDGPU/AMDGPUAtomicOptimizer.cpp
  llvm/trunk/test/CodeGen/AMDGPU/atomic_optimizations_buffer.ll


Index: llvm/trunk/test/CodeGen/AMDGPU/atomic_optimizations_buffer.ll
===================================================================
--- llvm/trunk/test/CodeGen/AMDGPU/atomic_optimizations_buffer.ll
+++ llvm/trunk/test/CodeGen/AMDGPU/atomic_optimizations_buffer.ll
@@ -47,7 +47,6 @@
 ; GFX8MORE: v_mov_b32_dpp v[[wave_shr1:[0-9]+]], v{{[0-9]+}} wave_shr:1 row_mask:0xf bank_mask:0xf
 ; GFX8MORE: v_mov_b32_dpp v{{[0-9]+}}, v[[wave_shr1]] row_shr:1 row_mask:0xf bank_mask:0xf
 ; GFX8MORE: v_mov_b32_dpp v{{[0-9]+}}, v[[wave_shr1]] row_shr:2 row_mask:0xf bank_mask:0xf
-; GFX8MORE: v_mov_b32_dpp v{{[0-9]+}}, v[[wave_shr1]] row_shr:3 row_mask:0xf bank_mask:0xf
 ; GFX8MORE: v_mov_b32_dpp v{{[0-9]+}}, v{{[0-9]+}} row_shr:4 row_mask:0xf bank_mask:0xe
 ; GFX8MORE: v_mov_b32_dpp v{{[0-9]+}}, v{{[0-9]+}} row_shr:8 row_mask:0xf bank_mask:0xc
 ; GFX8MORE: v_mov_b32_dpp v{{[0-9]+}}, v{{[0-9]+}} row_bcast:15 row_mask:0xa bank_mask:0xf
@@ -115,7 +114,6 @@
 ; GFX8MORE: v_mov_b32_dpp v[[wave_shr1:[0-9]+]], v{{[0-9]+}} wave_shr:1 row_mask:0xf bank_mask:0xf
 ; GFX8MORE: v_mov_b32_dpp v{{[0-9]+}}, v[[wave_shr1]] row_shr:1 row_mask:0xf bank_mask:0xf
 ; GFX8MORE: v_mov_b32_dpp v{{[0-9]+}}, v[[wave_shr1]] row_shr:2 row_mask:0xf bank_mask:0xf
-; GFX8MORE: v_mov_b32_dpp v{{[0-9]+}}, v[[wave_shr1]] row_shr:3 row_mask:0xf bank_mask:0xf
 ; GFX8MORE: v_mov_b32_dpp v{{[0-9]+}}, v{{[0-9]+}} row_shr:4 row_mask:0xf bank_mask:0xe
 ; GFX8MORE: v_mov_b32_dpp v{{[0-9]+}}, v{{[0-9]+}} row_shr:8 row_mask:0xf bank_mask:0xc
 ; GFX8MORE: v_mov_b32_dpp v{{[0-9]+}}, v{{[0-9]+}} row_bcast:15 row_mask:0xa bank_mask:0xf
Index: llvm/trunk/lib/Target/AMDGPU/AMDGPUAtomicOptimizer.cpp
===================================================================
--- llvm/trunk/lib/Target/AMDGPU/AMDGPUAtomicOptimizer.cpp
+++ llvm/trunk/lib/Target/AMDGPU/AMDGPUAtomicOptimizer.cpp
@@ -376,26 +376,24 @@
     CallInst *const SetInactive =
         B.CreateIntrinsic(Intrinsic::amdgcn_set_inactive, Ty, {V, Identity});
 
-    CallInst *const FirstDPP =
+    ExclScan =
         B.CreateIntrinsic(Intrinsic::amdgcn_update_dpp, Ty,
                           {Identity, SetInactive, B.getInt32(DPP_WF_SR1),
                            B.getInt32(0xf), B.getInt32(0xf), B.getFalse()});
-    ExclScan = FirstDPP;
 
-    const unsigned Iters = 7;
-    const unsigned DPPCtrl[Iters] = {
-        DPP_ROW_SR1, DPP_ROW_SR2,     DPP_ROW_SR3,    DPP_ROW_SR4,
-        DPP_ROW_SR8, DPP_ROW_BCAST15, DPP_ROW_BCAST31};
-    const unsigned RowMask[Iters] = {0xf, 0xf, 0xf, 0xf, 0xf, 0xa, 0xc};
-    const unsigned BankMask[Iters] = {0xf, 0xf, 0xf, 0xe, 0xc, 0xf, 0xf};
+    const unsigned Iters = 6;
+    const unsigned DPPCtrl[Iters] = {DPP_ROW_SR1,     DPP_ROW_SR2,
+                                     DPP_ROW_SR4,     DPP_ROW_SR8,
+                                     DPP_ROW_BCAST15, DPP_ROW_BCAST31};
+    const unsigned RowMask[Iters] = {0xf, 0xf, 0xf, 0xf, 0xa, 0xc};
+    const unsigned BankMask[Iters] = {0xf, 0xf, 0xe, 0xc, 0xf, 0xf};
 
     // This loop performs an exclusive scan across the wavefront, with all lanes
     // active (by using the WWM intrinsic).
     for (unsigned Idx = 0; Idx < Iters; Idx++) {
-      Value *const UpdateValue = Idx < 3 ? FirstDPP : ExclScan;
       CallInst *const DPP = B.CreateIntrinsic(
           Intrinsic::amdgcn_update_dpp, Ty,
-          {Identity, UpdateValue, B.getInt32(DPPCtrl[Idx]),
+          {Identity, ExclScan, B.getInt32(DPPCtrl[Idx]),
            B.getInt32(RowMask[Idx]), B.getInt32(BankMask[Idx]), B.getFalse()});
 
       ExclScan = buildNonAtomicBinOp(B, Op, ExclScan, DPP);


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