[AMDGPU] Early bail in getFunctionCodeSize for meta inst. NFC. (#127129)

It does not change the estimate because getInstSizeInBytes() already
returns 0 for meta instructions, but added a test and early bail.

Author: rampitec

llvm/lib/Target/AMDGPU/SIProgramInfo.cpp

@@ -215,8 +215,7 @@ uint64_t SIProgramInfo::getFunctionCodeSize(const MachineFunction &MF) {
     for (const MachineInstr &MI : MBB) {
       // TODO: CodeSize should account for multiple functions.
 
-      // TODO: Should we count size of debug info?
-      if (MI.isDebugInstr())
+      if (MI.isMetaInstruction())
         continue;
 
       CodeSize += TII->getInstSizeInBytes(MI);

llvm/test/CodeGen/AMDGPU/code-size-estimate.mir

@@ -18,3 +18,16 @@ body:             |
   $vgpr16 = V_MOV_B32_indirect_read undef $vgpr1, implicit $exec, implicit $m0, implicit $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15
   V_MOV_B32_indirect_write undef $vgpr0, undef $vgpr3, implicit $exec, implicit $m0, implicit-def $vgpr0_vgpr1_vgpr2_vgpr3, implicit killed $vgpr0_vgpr1_vgpr2_vgpr3(tied-def 4)
 ...
+
+# CHECK: meta:                                   ; @meta
+# CHECK: ; wave barrier
+# CHECK: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0) ; encoding: [0x00,0x00,0x8c,0xbf]
+# CHECK: ; codeLenInByte = 4
+---
+name:            meta
+tracksRegLiveness: true
+body:             |
+  bb.0:
+
+  WAVE_BARRIER
+...