[llvm] [AMDGPU] Insert before and after instructions that always use GDS (PR #131338)

[Jay Foad via llvm-commits]

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@@ -1982,6 +2003,65 @@ static bool isCacheInvOrWBInst(MachineInstr &Inst) {
          Opc == AMDGPU::GLOBAL_WBINV;
 }
 
+// Return true if the next instruction is S_ENDPGM, following fallthrough
+// blocks if necessary.
+bool SIInsertWaitcnts::isNextENDPGM(MachineBasicBlock::instr_iterator It,
+                                    MachineBasicBlock *Block) const {
+  auto E = Block->instr_end();
+
+  while (true) {
+    if (It == E) {
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jayfoad wrote:

But if you use `isEnd` then you don't need `E` for anything.

https://github.com/llvm/llvm-project/pull/131338