[PATCH] D82339: [HIP][AMDGPU] Do not perform Promote Alloca optimization for GPU kernels with dynamic LDS usage.

[Konstantin Pyzhov via Phabricator via llvm-commits]

kpyzhov created this revision.
kpyzhov added reviewers: yaxunl, b-sumner.
kpyzhov added a project: AMDGPU.
Herald added subscribers: llvm-commits, kerbowa, hiraditya, t-tye, tpr, dstuttard, nhaehnle, wdng, jvesely, kzhuravl, arsenm.
Herald added a project: LLVM.

The "Promote Alloca" optimization tries to move some stack allocations to statically allocated LDS, so it adds new static LDS loads/stores to the kernel.
Mixed static/dynamic LDS is not correctly supported by the hip-clang yet, so adding static LDS load/stores to a kernel that already has dynamic LDS operations causes conflicts.
This patch disables Promote Alloca optimization for kernels that use dynamic LDS.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D82339

Files:
  llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp


Index: llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
@@ -736,6 +736,12 @@
         continue;
 
       if (Use->getParent()->getParent() == &F) {
+        // Do not promote alloca to static LDS if this function uses any dynamic shared memory
+        // since mixed static/dynamic LDS is not fully supported yet.
+        uint64_t AllocSize = DL.getTypeAllocSize(GV.getValueType());
+        if (AllocSize == 0)
+          return false;
+
         unsigned Align = GV.getAlignment();
         if (Align == 0)
           Align = DL.getABITypeAlignment(GV.getValueType());
@@ -744,7 +750,6 @@
         // determined from the inverse order of uses in the function. I'm not
         // sure if the use list order is in any way connected to this, so the
         // total reported size is likely incorrect.
-        uint64_t AllocSize = DL.getTypeAllocSize(GV.getValueType());
         CurrentLocalMemUsage = alignTo(CurrentLocalMemUsage, Align);
         CurrentLocalMemUsage += AllocSize;
         break;


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