Merge commit '1b347223023d' from llvm.org/main into next

Author: git apple-llvm automerger

llvm/lib/Target/AMDGPU/AMDGPUSubtarget.cpp

@@ -191,17 +191,17 @@ std::pair<unsigned, unsigned> AMDGPUSubtarget::getEffectiveWavesPerEU(
       getOccupancyWithWorkGroupSizes(LDSBytes, FlatWorkGroupSizes).second};
   Default.first = std::min(Default.first, Default.second);
 
-  // Make sure requested minimum is less than requested maximum.
-  if (RequestedWavesPerEU.second &&
-      RequestedWavesPerEU.first > RequestedWavesPerEU.second)
-    return Default;
-
-  // Make sure requested values do not violate subtarget's specifications and
-  // are compatible with values implied by minimum/maximum flat workgroup sizes.
+  // Make sure requested minimum is within the default range and lower than the
+  // requested maximum. The latter must not violate target specification.
   if (RequestedWavesPerEU.first < Default.first ||
-      RequestedWavesPerEU.second > Default.second)
+      RequestedWavesPerEU.first > Default.second ||
+      RequestedWavesPerEU.first > RequestedWavesPerEU.second ||
+      RequestedWavesPerEU.second > getMaxWavesPerEU())
     return Default;
 
+  // We cannot exceed maximum occupancy implied by flat workgroup size and LDS.
+  RequestedWavesPerEU.second =
+      std::min(RequestedWavesPerEU.second, Default.second);
   return RequestedWavesPerEU;
 }
 

llvm/test/CodeGen/AMDGPU/attr-amdgpu-waves-per-eu.ll

@@ -200,3 +200,28 @@ entry:
   ret void
 }
 attributes #10 = {"amdgpu-flat-work-group-size"="256,256" "amdgpu-waves-per-eu"="2,2"}
+
+; Minimum 2 waves, maximum limited by LDS usage.
+; CHECK-LABEL: {{^}}empty_at_least_2_lds_limited:
+; CHECK: SGPRBlocks: 12
+; CHECK: VGPRBlocks: 12
+; CHECK: NumSGPRsForWavesPerEU: 102
+; CHECK: NumVGPRsForWavesPerEU: 49
+define amdgpu_kernel void @empty_at_least_2_lds_limited() #11 {
+entry:
+  ret void
+}
+attributes #11 = {"amdgpu-flat-work-group-size"="1,256" "amdgpu-waves-per-eu"="2" "amdgpu-lds-size"="16384"}
+
+; Minimum 2 waves, maximum limited by LDS usage. Requested maximum within spec
+; but above achievable occupancy has no effect.
+; CHECK-LABEL: {{^}}empty_at_least_2_lds_limited_max_above_achievable:
+; CHECK: SGPRBlocks: 12
+; CHECK: VGPRBlocks: 12
+; CHECK: NumSGPRsForWavesPerEU: 102
+; CHECK: NumVGPRsForWavesPerEU: 49
+define amdgpu_kernel void @empty_at_least_2_lds_limited_max_above_achievable() #12 {
+entry:
+  ret void
+}
+attributes #12 = {"amdgpu-flat-work-group-size"="1,256" "amdgpu-waves-per-eu"="2,10" "amdgpu-lds-size"="16384"}