commit 894c8fd0e2b8ff8ed9a5d54ef3d0e0167bacb612
author Ryan Taylor <rtayl@amd.com> Wed Aug 01 12:12:01 2018 +0000
committer Ryan Taylor <rtayl@amd.com> Wed Aug 01 12:12:01 2018 +0000
tree c66b42f3ddf9fdb840161f34c1553bbdfad3da81
parent f989cd78e4a814670856c7ada609da4cef4413b0

[AMDGPU] Optimize _L image intrinsic to _LZ when lod is zero

Summary:
Add _L to _LZ image intrinsic table mapping to table gen.
In ISelLowering check if image intrinsic has lod and if it's equal
to zero, if so remove lod and change opcode to equivalent mapped _LZ.

Change-Id: Ie24cd7e788e2195d846c7bd256151178cbb9ec71

Subscribers: arsenm, mehdi_amini, kzhuravl, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, steven_wu, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D49483

llvm-svn: 338523

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index 993c00d..2500786 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -4555,6 +4555,9 @@
   const AMDGPU::MIMGBaseOpcodeInfo *BaseOpcode =
       AMDGPU::getMIMGBaseOpcodeInfo(Intr->BaseOpcode);
   const AMDGPU::MIMGDimInfo *DimInfo = AMDGPU::getMIMGDimInfo(Intr->Dim);
+  const AMDGPU::MIMGLZMappingInfo *LZMappingInfo =
+      AMDGPU::getMIMGLZMappingInfo(Intr->BaseOpcode);
+  unsigned IntrOpcode = Intr->BaseOpcode;
 
   SmallVector<EVT, 2> ResultTypes(Op->value_begin(), Op->value_end());
   bool IsD16 = false;
@@ -4640,6 +4643,18 @@
   SmallVector<SDValue, 4> VAddrs;
   for (unsigned i = 0; i < NumVAddrs; ++i)
     VAddrs.push_back(Op.getOperand(AddrIdx + i));
+
+  // Optimize _L to _LZ when _L is zero
+  if (LZMappingInfo) {
+    if (auto ConstantLod =
+         dyn_cast<ConstantFPSDNode>(VAddrs[NumVAddrs-1].getNode())) {
+      if (ConstantLod->isZero() || ConstantLod->isNegative()) {
+        IntrOpcode = LZMappingInfo->LZ;  // set new opcode to _lz variant of _l
+        VAddrs.pop_back();               // remove 'lod'
+      }
+    }
+  }
+
   SDValue VAddr = getBuildDwordsVector(DAG, DL, VAddrs);
 
   SDValue True = DAG.getTargetConstant(1, DL, MVT::i1);
@@ -4699,10 +4714,10 @@
   int Opcode = -1;
 
   if (Subtarget->getGeneration() >= AMDGPUSubtarget::VOLCANIC_ISLANDS)
-    Opcode = AMDGPU::getMIMGOpcode(Intr->BaseOpcode, AMDGPU::MIMGEncGfx8,
+    Opcode = AMDGPU::getMIMGOpcode(IntrOpcode, AMDGPU::MIMGEncGfx8,
                                    NumVDataDwords, NumVAddrDwords);
   if (Opcode == -1)
-    Opcode = AMDGPU::getMIMGOpcode(Intr->BaseOpcode, AMDGPU::MIMGEncGfx6,
+    Opcode = AMDGPU::getMIMGOpcode(IntrOpcode, AMDGPU::MIMGEncGfx6,
                                    NumVDataDwords, NumVAddrDwords);
   assert(Opcode != -1);