AMDGPU: Create InstrMapping from VGPR MFMA to equivalent AGPR instruction

This provides infrastructure for a future optimization.

Author: arsenm

llvm/lib/Target/AMDGPU/SIInstrInfo.h

@@ -1568,6 +1568,11 @@ namespace AMDGPU {
   LLVM_READONLY
   int getMFMAEarlyClobberOp(uint16_t Opcode);
 
+  /// \returns Version of an MFMA instruction which uses AGPRs for srcC and
+  /// vdst, given an \p Opcode of an MFMA which uses VGPRs for srcC/vdst.
+  LLVM_READONLY
+  int getMFMASrcCVDstAGPROp(uint16_t Opcode);
+
   /// \returns v_cmpx version of a v_cmp instruction.
   LLVM_READONLY
   int getVCMPXOpFromVCMP(uint16_t Opcode);

llvm/lib/Target/AMDGPU/SIInstrInfo.td

@@ -3146,6 +3146,15 @@ def getMFMAEarlyClobberOp : InstrMapping {
   let ValueCols = [["0"]];
 }
 
+// Map from an mfma using VGPRs to one using AGPRs.
+def getMFMASrcCVDstAGPROp : InstrMapping {
+  let FilterClass = "MFMATable";
+  let RowFields = ["AGPROp"];
+  let ColFields = ["MFMAKind"];
+  let KeyCol = ["VGPR"];
+  let ValueCols = [["AGPR"]];
+}
+
 // Maps an v_cmp instruction to its v_cmpx equivalent.
 def getVCMPXOpFromVCMP : InstrMapping {
   let FilterClass = "VCMPVCMPXTable";

llvm/lib/Target/AMDGPU/VOP3PInstructions.td

@@ -721,9 +721,14 @@ def VOPProfileMAI_F32_V4I32_V4I32_X512_VCD : VOPProfileMAI<VOP_V16F32_V4I32_V4I3
 }
 
 
-class MFMATable <bit is_mac, string Name> {
+class MFMATable <bit is_mac, string Kind, string Name,
+                 string AGPROpName = NAME> {
   bit IsMac = is_mac;
   string FMAOp = Name;
+  string AGPROp = AGPROpName;
+
+  // Does this MFMA use "AGPR" or "VGPR" for srcC/vdst
+  string MFMAKind = Kind;
 }
 
 class MFMA_F8F6F4_WithSizeTable<int A, int B, Instruction ThisVariant, Instruction F8F8Variant> {
@@ -829,12 +834,12 @@ multiclass MAIInst<string OpName, string P, SDPatternOperator node = null_frag,
     let Constraints = !if(NoDstOverlap, "@earlyclobber $vdst", "") in {
       def _e64 : MAIInst<OpName, !cast<VOPProfileMAI>("VOPProfileMAI_" # P),
                          !if(!or(NoDstOverlap, !eq(node, null_frag)), null_frag, AgprMAIFrag<node, HasAbid, Scaled>), Scaled>,
-                 MFMATable<0, NAME # "_e64">;
+                 MFMATable<0, "AGPR", NAME # "_e64">;
 
       let OtherPredicates = [isGFX90APlus], Mnemonic = OpName in
       def _vgprcd_e64 : MAIInst<OpName # "_vgprcd", !cast<VOPProfileMAI>("VOPProfileMAI_" # P # "_VCD"),
                                 !if(!or(NoDstOverlap, !eq(node, null_frag)), null_frag, VgprMAIFrag<node, HasAbid, Scaled>), Scaled>,
-                        MFMATable<0, NAME # "_vgprcd_e64">;
+                        MFMATable<0, "VGPR", NAME # "_vgprcd_e64", NAME # "_e64">;
     }
 
     if NoDstOverlap then {
@@ -843,6 +848,7 @@ multiclass MAIInst<string OpName, string P, SDPatternOperator node = null_frag,
           Mnemonic = OpName in {
         def "_mac_e64" : MAIInst<OpName # "_mac", !cast<VOPProfileMAI>("VOPProfileMAI_" # P),
                                  !if(!eq(node, null_frag), null_frag, AgprMAIFrag<node, HasAbid, Scaled>), Scaled>,
+                         MFMATable<1, "AGPR", NAME # "_e64", NAME # "_mac_e64">;
                          MFMATable<1, NAME # "_e64">;
 
         let OtherPredicates = [isGFX90APlus] in