[X86] X86InstrInfo::commuteInstructionImpl - remove (V)BLENDPD/S commutation to (V)MOVSD/S optsize handling

[RKSimon]

Just commute with (V)BLENDPD/S like all other BLEND instructions

This is now handled more generally by the X86FixupInstTuningPass (OptSize fold occurs even without a scheduler model).

First step towards #142972

[llvmbot]

@llvm/pr-subscribers-backend-x86

Author: Simon Pilgrim (RKSimon)

Changes

Just commute with (V)BLENDPD/S like all other BLEND instructions

This is now handled more generally by the X86FixupInstTuningPass (OptSize fold occurs even without a scheduler model).

First step towards #142972

---

Full diff: https://github.com/llvm/llvm-project/pull/144051.diff

1 Files Affected:

• (modified) llvm/lib/Target/X86/X86InstrInfo.cpp (+1-25)

diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 212e134c512a7..abf365eedec39 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -2353,33 +2353,9 @@ MachineInstr *X86InstrInfo::commuteInstructionImpl(MachineInstr &MI, bool NewMI,
     break;
   case X86::BLENDPDrri:
   case X86::BLENDPSrri:
+  case X86::PBLENDWrri:
   case X86::VBLENDPDrri:
   case X86::VBLENDPSrri:
-    // If we're optimizing for size, try to use MOVSD/MOVSS.
-    if (MI.getParent()->getParent()->getFunction().hasOptSize()) {
-      unsigned Mask = (Opc == X86::BLENDPDrri || Opc == X86::VBLENDPDrri) ? 0x03: 0x0F;
-      if ((MI.getOperand(3).getImm() ^ Mask) == 1) {
-#define FROM_TO(FROM, TO)                                                      \
-  case X86::FROM:                                                              \
-    Opc = X86::TO;                                                             \
-    break;
-        switch (Opc) {
-        default:
-          llvm_unreachable("Unreachable!");
-        FROM_TO(BLENDPDrri, MOVSDrr)
-        FROM_TO(BLENDPSrri, MOVSSrr)
-        FROM_TO(VBLENDPDrri, VMOVSDrr)
-        FROM_TO(VBLENDPSrri, VMOVSSrr)
-        }
-        WorkingMI = CloneIfNew(MI);
-        WorkingMI->setDesc(get(Opc));
-        WorkingMI->removeOperand(3);
-        break;
-      }
-#undef FROM_TO
-    }
-    [[fallthrough]];
-  case X86::PBLENDWrri:
   case X86::VBLENDPDYrri:
   case X86::VBLENDPSYrri:
   case X86::VPBLENDDrri: