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

[Jay Foad via llvm-commits]

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@@ -1678,6 +1694,12 @@ bool SIInsertWaitcnts::generateWaitcntInstBefore(MachineInstr &MI,
       }
     }
 
+    // GFX11 must wait for any pending GDS instruction to complete before
+    // any "Always GDS" instruction.
+    if (AMDGPU::isGFX11(*ST) && TII->isAlwaysGDS(MI.getOpcode()) &&
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jayfoad wrote:

Don't restrict this to GFX11. The rule definitely applies to GFX9 and GFX10 too, so I'm guessing it applies to any architecture that supports GWS and this code can be unconditional.

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