[llvm] AMDGPU: Create InstrMapping from VGPR MFMA to equivalent AGPR instruction (PR #117102)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-amdgpu

Author: Matt Arsenault (arsenm)

<details>
<summary>Changes</summary>

This provides infrastructure for a future optimization.

---
Full diff: https://github.com/llvm/llvm-project/pull/117102.diff


3 Files Affected:

- (modified) llvm/lib/Target/AMDGPU/SIInstrInfo.h (+5) 
- (modified) llvm/lib/Target/AMDGPU/SIInstrInfo.td (+9) 
- (modified) llvm/lib/Target/AMDGPU/VOP3PInstructions.td (+10-5) 


``````````diff
diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.h b/llvm/lib/Target/AMDGPU/SIInstrInfo.h
index 1f7fff76d15210..191754d04aa172 100644
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.h
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.h
@@ -1562,6 +1562,11 @@ 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);
diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.td b/llvm/lib/Target/AMDGPU/SIInstrInfo.td
index d2024cf915874d..90292a6e59387c 100644
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.td
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.td
@@ -3105,6 +3105,15 @@ 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";
diff --git a/llvm/lib/Target/AMDGPU/VOP3PInstructions.td b/llvm/lib/Target/AMDGPU/VOP3PInstructions.td
index 876d4e1acf5964..c1bd5296dfc5fb 100644
--- a/llvm/lib/Target/AMDGPU/VOP3PInstructions.td
+++ b/llvm/lib/Target/AMDGPU/VOP3PInstructions.td
@@ -639,9 +639,14 @@ def VOPProfileMAI_F32_V8F16_X16_VCD : VOPProfileMAI<VOP_V16F32_V8F16_V8F16_V16F3
 def VOPProfileMAI_F32_V8BF16_X16     : VOPProfileMAI<VOP_V16F32_V8BF16_V8BF16_V16F32,     AISrc_512_f32,  ADst_512, AVSrc_128>;
 def VOPProfileMAI_F32_V8BF16_X16_VCD : VOPProfileMAI<VOP_V16F32_V8BF16_V8BF16_V16F32,     VISrc_512_f32,  VDst_512, AVSrc_128>;
 
-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 MAIFrag<SDPatternOperator Op, code pred> : PatFrag <
@@ -697,12 +702,12 @@ multiclass MAIInst<string OpName, string P, SDPatternOperator node> {
     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>)>,
-                 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>)>,
-                        MFMATable<0, NAME # "_vgprcd_e64">;
+                        MFMATable<0, "VGPR", NAME # "_vgprcd_e64", NAME # "_e64">;
     }
 
     if NoDstOverlap then {
@@ -711,12 +716,12 @@ multiclass MAIInst<string OpName, string P, SDPatternOperator node> {
           Mnemonic = OpName in {
         def "_mac_e64" : MAIInst<OpName # "_mac", !cast<VOPProfileMAI>("VOPProfileMAI_" # P),
                                  !if(!eq(node, null_frag), null_frag, AgprMAIFrag<node>)>,
-                         MFMATable<1, NAME # "_e64">;
+                         MFMATable<1, "AGPR", NAME # "_e64", NAME # "_mac_e64">;
 
         let OtherPredicates = [isGFX90APlus] in
         def _mac_vgprcd_e64 : MAIInst<OpName # "_mac_vgprcd", !cast<VOPProfileMAI>("VOPProfileMAI_" # P # "_VCD"),
                                       !if(!eq(node, null_frag), null_frag, VgprMAIFrag<node>)>,
-                              MFMATable<1, NAME # "_vgprcd_e64">;
+                              MFMATable<1, "VGPR", NAME # "_vgprcd_e64", NAME # "_mac_e64">;
       }
     }
   } // End isConvergent = 1, mayRaiseFPException = 0, ReadsModeReg = 1

``````````

</details>


https://github.com/llvm/llvm-project/pull/117102