[PATCH] D102347: [AMDGPU] Only allow global fp atomics with unsafe option

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

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Previously we were allowing to use FP atomics without
-amdgpu-unsafe-fp-atomics option if a scope is less then
system. This is not safe just as well if we have UC memory.

This change only allows global and flat FP atomics with
the unsafe option. Consequentially that makes a check for
denorm mode redundant since we skip it with the unsafe
option and do not have a way to produce these instructions
without it anyway.


https://reviews.llvm.org/D102347

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


Index: llvm/lib/Target/AMDGPU/SIISelLowering.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -12122,10 +12122,9 @@
       // floating point atomic instructions. May generate more efficient code,
       // but may not respect rounding and denormal modes, and may give incorrect
       // results for certain memory destinations.
-      if (!fpModeMatchesGlobalFPAtomicMode(RMW) &&
-          RMW->getFunction()
-                  ->getFnAttribute("amdgpu-unsafe-fp-atomics")
-                  .getValueAsString() != "true")
+      if (RMW->getFunction()
+              ->getFnAttribute("amdgpu-unsafe-fp-atomics")
+              .getValueAsString() != "true")
         return AtomicExpansionKind::CmpXChg;
 
       if (Subtarget->hasGFX90AInsts()) {


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