[llvm] [AMDGPU] Add s_delay_alu in relocated PC-relative symbol sequence (PR #71061)

[Jay Foad via llvm-commits]

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@@ -2405,13 +2405,22 @@ bool SIInstrInfo::expandPostRAPseudo(MachineInstr &MI) const {
     // the encoding of $symbol starts 12 bytes after the start of the s_add_u32
     // instruction.
 
+    int64_t Adjust = 0;
+    if (ST.hasDelayAlu()) {
+      // Manually add the 1 cycle delay before using RegLo. AMDGPUInsertDelayAlu
+      // will not add this automatically inside a bundle:
+      //   s_delay_alu instid0(SALU_CYCLE_1)
+      Bundler.append(BuildMI(MF, DL, get(AMDGPU::S_DELAY_ALU)).addImm(9));
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jayfoad wrote:

Open question: should the existing command line flag `-amdgpu-enable-delay-alu=0` disable this? Or should that flag only disable running the `AMDGPUInsertDelayAlu` pass?

https://github.com/llvm/llvm-project/pull/71061