[RISCV][VLOPT] Handle tied pseudos in getOperandInfo

[lukel97]

For .wv widening instructions when checking if the opperand is vs1 or vs2, we take into account whether or not it has a passthru. For tied pseudos though their passthru is the vs2, and we weren't taking this into account.

[llvmbot]

@llvm/pr-subscribers-backend-risc-v

Author: Luke Lau (lukel97)

Changes

For .wv widening instructions when checking if the opperand is vs1 or vs2, we take into account whether or not it has a passthru. For tied pseudos though their passthru is the vs2, and we weren't taking this into account.

---

Full diff: https://github.com/llvm/llvm-project/pull/123170.diff

3 Files Affected:

• (modified) llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp (+4-1)
• (modified) llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir (+30)
• (modified) llvm/test/CodeGen/RISCV/rvv/vl-opt.mir (+9-1)

diff --git a/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp b/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
index 8156eaff8a04c6..54ca8ccd8d9e90 100644
--- a/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
+++ b/llvm/lib/Target/RISCV/RISCVVLOptimizer.cpp
@@ -206,6 +206,7 @@ getOperandLog2EEW(const MachineOperand &MO, const MachineRegisterInfo *MRI) {
       MI.getOperand(RISCVII::getSEWOpNum(MI.getDesc())).getImm();
 
   const bool HasPassthru = RISCVII::isFirstDefTiedToFirstUse(MI.getDesc());
+  const bool IsTied = RISCVII::isTiedPseudo(MI.getDesc().TSFlags);
 
   // We bail out early for instructions that have passthru with non NoRegister,
   // which means they are using TU policy. We are not interested in these
@@ -568,7 +569,8 @@ getOperandLog2EEW(const MachineOperand &MO, const MachineRegisterInfo *MRI) {
   case RISCV::VFWADD_WV:
   case RISCV::VFWSUB_WF:
   case RISCV::VFWSUB_WV: {
-    bool IsOp1 = HasPassthru ? MO.getOperandNo() == 2 : MO.getOperandNo() == 1;
+    bool IsOp1 = (HasPassthru && !IsTied) ? MO.getOperandNo() == 2
+                                          : MO.getOperandNo() == 1;
     bool TwoTimes = IsMODef || IsOp1;
     return TwoTimes ? MILog2SEW + 1 : MILog2SEW;
   }
@@ -610,6 +612,7 @@ getOperandLog2EEW(const MachineOperand &MO, const MachineRegisterInfo *MRI) {
   case RISCV::VFNCVT_F_F_W:
   case RISCV::VFNCVT_ROD_F_F_W:
   case RISCV::VFNCVTBF16_F_F_W: {
+    assert(!IsTied);
     bool IsOp1 = HasPassthru ? MO.getOperandNo() == 2 : MO.getOperandNo() == 1;
     bool TwoTimes = IsOp1;
     return TwoTimes ? MILog2SEW + 1 : MILog2SEW;
diff --git a/llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir b/llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir
index fe0929a6f87459..edcd32c4098bca 100644
--- a/llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir
+++ b/llvm/test/CodeGen/RISCV/rvv/vl-opt-op-info.mir
@@ -243,6 +243,36 @@ body: |
     %y:vrm2 = PseudoVWADD_WV_M1 $noreg, $noreg, %x, 1, 3 /* e8 */, 0
 ...
 ---
+name: tied_vwop_wv_vs1
+body: |
+  bb.0:
+    ; CHECK-LABEL: name: tied_vwop_wv_vs1
+    ; CHECK: %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, 1, 3 /* e8 */, 0 /* tu, mu */
+    ; CHECK-NEXT: early-clobber %y:vrm2 = PseudoVWADD_WV_M1_TIED $noreg, %x, 1, 3 /* e8 */, 0 /* tu, mu */
+    %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0
+    %y:vrm2 = PseudoVWADD_WV_M1_TIED $noreg, %x, 1, 3 /* e8 */, 0
+...
+---
+name: tied_vwop_wv_vs1_incompatible_eew
+body: |
+  bb.0:
+    ; CHECK-LABEL: name: tied_vwop_wv_vs1_incompatible_eew
+    ; CHECK: %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 4 /* e16 */, 0 /* tu, mu */
+    ; CHECK-NEXT: early-clobber %y:vrm2 = PseudoVWADD_WV_M1_TIED $noreg, %x, 1, 3 /* e8 */, 0 /* tu, mu */
+    %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 4 /* e16 */, 0
+    %y:vrm2 = PseudoVWADD_WV_M1_TIED $noreg, %x, 1, 3 /* e8 */, 0
+...
+---
+name: tied_vwop_wv_vs1_incompatible_emul
+body: |
+  bb.0:
+    ; CHECK-LABEL: name: tied_vwop_wv_vs1_incompatible_emul
+    ; CHECK: %x:vr = PseudoVADD_VV_MF2 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0 /* tu, mu */
+    ; CHECK-NEXT: early-clobber %y:vrm2 = PseudoVWADD_WV_M1_TIED $noreg, %x, 1, 3 /* e8 */, 0 /* tu, mu */
+    %x:vr = PseudoVADD_VV_MF2 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0
+    %y:vrm2 = PseudoVWADD_WV_M1_TIED $noreg, %x, 1, 3 /* e8 */, 0
+...
+---
 name: vop_vf2_vd
 body: |
   bb.0:
diff --git a/llvm/test/CodeGen/RISCV/rvv/vl-opt.mir b/llvm/test/CodeGen/RISCV/rvv/vl-opt.mir
index 56bfe0fd3eb938..7b210d6d0b162f 100644
--- a/llvm/test/CodeGen/RISCV/rvv/vl-opt.mir
+++ b/llvm/test/CodeGen/RISCV/rvv/vl-opt.mir
@@ -140,4 +140,12 @@ body: |
     %x:vr = nofpexcept PseudoVFNCVTBF16_F_F_W_M1_E16 $noreg, $noreg, 7, -1, 4 /* e16 */, 0 /* tu, mu */, implicit $frm
     %y:vr = PseudoVADD_VV_M1 $noreg, %x, $noreg, 1, 4 /* e16 */, 0
 ...
-
+---
+name: vwaddu_
+body: |
+  bb.0:
+    ; CHECK-LABEL: name: vwaddu_
+    ; CHECK: %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, 1, 3 /* e8 */, 0 /* tu, mu */
+    ; CHECK-NEXT: early-clobber %y:vrm2 = PseudoVWADD_WV_M1_TIED $noreg, %x, 1, 3 /* e8 */, 0 /* tu, mu */
+    %x:vr = PseudoVADD_VV_M1 $noreg, $noreg, $noreg, -1, 3 /* e8 */, 0 /* tu, mu */
+    %y:vrm2 = PseudoVWADD_WV_M1_TIED $noreg, %x, 1, 3 /* e8 */, 0 /* tu, mu */

[wangpc-pp]

LGTM.

[wangpc-pp]

I am inclined to use another name instead of IsOp1 because it doesn't make sense here, IsVS1 seems to be more suitable.
Since there are more other cases, this can be a NFC follow-up. :-)

[michaelmaitland]

LGTM, minor nit

[michaelmaitland]

trailing _?