[llvm] [X86][CodeGen] Teach frame lowering to spill/reload registers w/ PUSHP/POPP, PUSH2[P]/POP2[P] (PR #73292)

[Phoebe Wang via llvm-commits]

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@@ -1818,18 +1852,30 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF,
   // Skip the callee-saved push instructions.
   bool PushedRegs = false;
   int StackOffset = 2 * stackGrowth;
+  MachineBasicBlock::iterator LastCSPush = MBBI;
+  auto IsCSPush = [&](const MachineBasicBlock::iterator &MBBI) {
+    if (MBBI == MBB.end() || !MBBI->getFlag(MachineInstr::FrameSetup))
+      return false;
+    unsigned Opc = MBBI->getOpcode();
+    return Opc == X86::PUSH32r || Opc == X86::PUSH64r || Opc == X86::PUSHP64r ||
+           Opc == X86::PUSH2 || Opc == X86::PUSH2P;
+  };
 
-  while (MBBI != MBB.end() && MBBI->getFlag(MachineInstr::FrameSetup) &&
-         (MBBI->getOpcode() == X86::PUSH32r ||
-          MBBI->getOpcode() == X86::PUSH64r)) {
+  while (IsCSPush(MBBI)) {
     PushedRegs = true;
     Register Reg = MBBI->getOperand(0).getReg();
+    LastCSPush = MBBI;
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phoebewang wrote:

You don't need to save the last MBBI. All you need it just it's opcode and register.

https://github.com/llvm/llvm-project/pull/73292