[PATCH] D128346: [AMDGPU] Set scratch size to 0 if is_dynamic_callstack is set

[Abinav Puthan Purayil via Phabricator via llvm-commits]

abinavpp added inline comments.


================
Comment at: llvm/lib/Target/AMDGPU/AMDGPUAsmPrinter.cpp:698-699
+      Info.HasDynamicallySizedStack || Info.HasRecursion;
+  ProgInfo.ScratchSize =
+      ProgInfo.DynamicCallStack ? 0 : Info.PrivateSegmentSize;
   ProgInfo.VCCUsed = Info.UsesVCC;
----------------
arsenm wrote:
> Dynamic call size does not imply 0 for the statically reported size. We still need to report the minimum statically known requirement
Does that mean we should do the following instead?

```
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUResourceUsageAnalysis.cpp b/llvm/lib/Target/AMDGPU/AMDGPUResourceUsageAnalysis.cpp
index f7f93c75c870..e6a5aa989c9d 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUResourceUsageAnalysis.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUResourceUsageAnalysis.cpp
@@ -165,8 +151,6 @@ AMDGPUResourceUsageAnalysis::analyzeResourceUsage(
 
   // Assume a big number if there are any unknown sized objects.
   Info.HasDynamicallySizedStack = FrameInfo.hasVarSizedObjects();
-  if (Info.HasDynamicallySizedStack)
-    Info.PrivateSegmentSize += AssumedStackSizeForDynamicSizeObjects;
 
   if (MFI->isStackRealigned())
     Info.PrivateSegmentSize += FrameInfo.getMaxAlign().value();
@@ -469,16 +453,12 @@ AMDGPUResourceUsageAnalysis::analyzeResourceUsage(
             // directly call the tail called function. If a kernel directly
             // calls a tail recursive function, we'll assume maximum stack size
             // based on the regular call instruction.
-            CalleeFrameSize =
-              std::max(CalleeFrameSize,
-                       static_cast<uint64_t>(AssumedStackSizeForExternalCall));
+            CalleeFrameSize = 0;
           }
         }
 
         if (IsIndirect || I == CallGraphResourceInfo.end()) {
-          CalleeFrameSize =
-              std::max(CalleeFrameSize,
-                       static_cast<uint64_t>(AssumedStackSizeForExternalCall));
+          CalleeFrameSize = 0;
```


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D128346/new/

https://reviews.llvm.org/D128346