Index: llvm/lib/Target/AMDGPU/SIISelLowering.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -11773,7 +11773,9 @@
     unsigned AS = RMW->getPointerAddressSpace();
 
     if (AS == AMDGPUAS::GLOBAL_ADDRESS && Subtarget->hasAtomicFaddInsts()) {
-      if (!fpModeMatchesGlobalFPAtomicMode(RMW))
+      if (!fpModeMatchesGlobalFPAtomicMode(RMW) ||
+          RMW->getFunction()->getFnAttribute("amdgpu-unsafe-fp-atomics")
+              .getValueAsString() != "true")
         return AtomicExpansionKind::CmpXChg;
 
       return RMW->use_empty() ? AtomicExpansionKind::None :
Index: llvm/test/CodeGen/AMDGPU/global-atomics-fp.ll
===================================================================
--- llvm/test/CodeGen/AMDGPU/global-atomics-fp.ll
+++ llvm/test/CodeGen/AMDGPU/global-atomics-fp.ll
@@ -61,5 +61,5 @@
   ret void
 }
 
-attributes #0 = { "denormal-fp-math-f32"="preserve-sign,preserve-sign"}
+attributes #0 = { "denormal-fp-math-f32"="preserve-sign,preserve-sign" "amdgpu-unsafe-fp-atomics"="true" }
 attributes #1 = { "denormal-fp-math-f32"="preserve-sign,preserve-sign" "target-cpu"="gfx803" "target-features"="+atomic-fadd-insts" }
Index: llvm/test/Transforms/AtomicExpand/AMDGPU/expand-atomic-rmw-fadd.ll
===================================================================
--- llvm/test/Transforms/AtomicExpand/AMDGPU/expand-atomic-rmw-fadd.ll
+++ llvm/test/Transforms/AtomicExpand/AMDGPU/expand-atomic-rmw-fadd.ll
@@ -463,4 +463,4 @@
   ret double %res
 }
 
-attributes #0 = { "denormal-fp-math-f32"="preserve-sign,preserve-sign" }
+attributes #0 = { "denormal-fp-math-f32"="preserve-sign,preserve-sign" "amdgpu-unsafe-fp-atomics"="true" }