[llvm] [AMDGPU] Add support for GFX12 expert scheduling mode 2 (PR #170319)

[Nicolai Hähnle via llvm-commits]

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@@ -2741,7 +2979,14 @@ bool SIInsertWaitcnts::run(MachineFunction &MF) {
   AMDGPU::IsaVersion IV = AMDGPU::getIsaVersion(ST->getCPU());
 
   if (ST->hasExtendedWaitCounts()) {
-    MaxCounter = NUM_EXTENDED_INST_CNTS;
+    if (ST->hasSoftwareHazardMode() &&
+        (MF.getFunction()
+             .getFnAttribute("amdgpu-software-hazard-mode")
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nhaehnle wrote:

> the compiler only supports setting it once at the start of an entry function

One option would be to just change that. Basically, make it part of the function call ABI that DEP_MODE==0 at function call boundaries, and reset the bit around function calls so that it's a genuinely per-function choice.

https://github.com/llvm/llvm-project/pull/170319