[AMDGPU][InstCombine] Remove zero image offset

Remove the offset parameter if it is zero.

Differential Revision: https://reviews.llvm.org/D117876

llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp

@@ -182,6 +182,23 @@ simplifyAMDGCNImageIntrinsic(const GCNSubtarget *ST,
     }
   }
 
+  // Optimize _offset away when 'offset' is zero
+  if (const auto *OffsetMappingInfo =
+          AMDGPU::getMIMGOffsetMappingInfo(ImageDimIntr->BaseOpcode)) {
+    if (auto *ConstantOffset =
+            dyn_cast<ConstantInt>(II.getOperand(ImageDimIntr->OffsetIndex))) {
+      if (ConstantOffset->isZero()) {
+        const AMDGPU::ImageDimIntrinsicInfo *NewImageDimIntr =
+            AMDGPU::getImageDimIntrinsicByBaseOpcode(
+                OffsetMappingInfo->NoOffset, ImageDimIntr->Dim);
+        return modifyIntrinsicCall(
+            II, NewImageDimIntr->Intr, IC, [&](auto &Args, auto &ArgTys) {
+              Args.erase(Args.begin() + ImageDimIntr->OffsetIndex);
+            });
+      }
+    }
+  }
+
   // Try to use A16 or G16
   if (!ST->hasA16() && !ST->hasG16())
     return None;

llvm/lib/Target/AMDGPU/MIMGInstructions.td

@@ -147,6 +147,22 @@ def MIMGBiasMappingTable : GenericTable {
   let PrimaryKeyName = "getMIMGBiasMappingInfo";
 }
 
+class MIMGOffsetMapping<MIMGBaseOpcode offset, MIMGBaseOpcode nooffset> {
+  MIMGBaseOpcode Offset = offset;
+  MIMGBaseOpcode NoOffset = nooffset;
+}
+
+def MIMGOffsetMappingTable : GenericTable {
+  let FilterClass = "MIMGOffsetMapping";
+  let CppTypeName = "MIMGOffsetMappingInfo";
+  let Fields = ["Offset", "NoOffset"];
+  string TypeOf_Offset = "MIMGBaseOpcode";
+  string TypeOf_NoOffset = "MIMGBaseOpcode";
+
+  let PrimaryKey = ["Offset"];
+  let PrimaryKeyName = "getMIMGOffsetMappingInfo";
+}
+
 class MIMGG16Mapping<MIMGBaseOpcode g, MIMGBaseOpcode g16> {
   MIMGBaseOpcode G = g;
   MIMGBaseOpcode G16 = g16;
@@ -1174,6 +1190,48 @@ def : MIMGBiasMapping<IMAGE_GATHER4_B_CL_O, IMAGE_GATHER4_CL_O>;
 def : MIMGBiasMapping<IMAGE_GATHER4_C_B_O, IMAGE_GATHER4_C_O>;
 def : MIMGBiasMapping<IMAGE_GATHER4_C_B_CL_O, IMAGE_GATHER4_C_CL_O>;
 
+// Offset to NoOffset Optimization Mapping
+def : MIMGOffsetMapping<IMAGE_SAMPLE_O, IMAGE_SAMPLE>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_CL_O, IMAGE_SAMPLE_CL>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_D_O, IMAGE_SAMPLE_D>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_D_CL_O, IMAGE_SAMPLE_D_CL>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_D_O_G16, IMAGE_SAMPLE_D_G16>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_D_CL_O_G16, IMAGE_SAMPLE_D_CL_G16>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_L_O, IMAGE_SAMPLE_L>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_B_O, IMAGE_SAMPLE_B>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_B_CL_O, IMAGE_SAMPLE_B_CL>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_LZ_O, IMAGE_SAMPLE_LZ>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_O, IMAGE_SAMPLE_C>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_CL_O, IMAGE_SAMPLE_C_CL>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_D_O, IMAGE_SAMPLE_C_D>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_D_CL_O, IMAGE_SAMPLE_C_D_CL>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_D_O_G16, IMAGE_SAMPLE_C_D_G16>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_D_CL_O_G16, IMAGE_SAMPLE_C_D_CL_G16>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_L_O, IMAGE_SAMPLE_C_L>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_B_CL_O, IMAGE_SAMPLE_C_B_CL>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_B_O, IMAGE_SAMPLE_C_B>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_LZ_O, IMAGE_SAMPLE_C_LZ>;
+def : MIMGOffsetMapping<IMAGE_GATHER4_O, IMAGE_GATHER4>;
+def : MIMGOffsetMapping<IMAGE_GATHER4_CL_O, IMAGE_GATHER4_CL>;
+def : MIMGOffsetMapping<IMAGE_GATHER4_L_O, IMAGE_GATHER4_L>;
+def : MIMGOffsetMapping<IMAGE_GATHER4_B_O, IMAGE_GATHER4_B>;
+def : MIMGOffsetMapping<IMAGE_GATHER4_B_CL_O, IMAGE_GATHER4_B_CL>;
+def : MIMGOffsetMapping<IMAGE_GATHER4_LZ_O, IMAGE_GATHER4_LZ>;
+def : MIMGOffsetMapping<IMAGE_GATHER4_C_O, IMAGE_GATHER4_C>;
+def : MIMGOffsetMapping<IMAGE_GATHER4_C_CL_O, IMAGE_GATHER4_C_CL>;
+def : MIMGOffsetMapping<IMAGE_GATHER4_C_L_O, IMAGE_GATHER4_C_L>;
+def : MIMGOffsetMapping<IMAGE_GATHER4_C_B_O, IMAGE_GATHER4_C_B>;
+def : MIMGOffsetMapping<IMAGE_GATHER4_C_B_CL_O, IMAGE_GATHER4_C_B_CL>;
+def : MIMGOffsetMapping<IMAGE_GATHER4_C_LZ_O, IMAGE_GATHER4_C_LZ>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_CD_O, IMAGE_SAMPLE_CD>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_CD_CL_O, IMAGE_SAMPLE_CD_CL>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_CD_O, IMAGE_SAMPLE_C_CD>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_CD_CL_O, IMAGE_SAMPLE_C_CD_CL>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_CD_O_G16, IMAGE_SAMPLE_CD_G16>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_CD_CL_O_G16, IMAGE_SAMPLE_CD_CL_G16>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_CD_O_G16, IMAGE_SAMPLE_C_CD_G16>;
+def : MIMGOffsetMapping<IMAGE_SAMPLE_C_CD_CL_O_G16, IMAGE_SAMPLE_C_CD_CL_G16>;
+
 // G to G16 Optimization Mapping
 def : MIMGG16Mapping<IMAGE_SAMPLE_D, IMAGE_SAMPLE_D_G16>;
 def : MIMGG16Mapping<IMAGE_SAMPLE_D_CL, IMAGE_SAMPLE_D_CL_G16>;

llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp

@@ -133,6 +133,7 @@ bool isHsaAbiVersion3Or4(const MCSubtargetInfo *STI) {
 #define GET_MIMGLZMappingTable_IMPL
 #define GET_MIMGMIPMappingTable_IMPL
 #define GET_MIMGBiasMappingTable_IMPL
+#define GET_MIMGOffsetMappingTable_IMPL
 #define GET_MIMGG16MappingTable_IMPL
 #include "AMDGPUGenSearchableTables.inc"
 

llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h

@@ -336,6 +336,11 @@ struct MIMGBiasMappingInfo {
   MIMGBaseOpcode NoBias;
 };
 
+struct MIMGOffsetMappingInfo {
+  MIMGBaseOpcode Offset;
+  MIMGBaseOpcode NoOffset;
+};
+
 struct MIMGG16MappingInfo {
   MIMGBaseOpcode G;
   MIMGBaseOpcode G16;
@@ -350,6 +355,9 @@ const MIMGMIPMappingInfo *getMIMGMIPMappingInfo(unsigned MIP);
 LLVM_READONLY
 const MIMGBiasMappingInfo *getMIMGBiasMappingInfo(unsigned Bias);
 
+LLVM_READONLY
+const MIMGOffsetMappingInfo *getMIMGOffsetMappingInfo(unsigned Offset);
+
 LLVM_READONLY
 const MIMGG16MappingInfo *getMIMGG16MappingInfo(unsigned G);