AMDGPU: Assume xnack is enabled by default

lib/Target/AMDGPU/AMDGPU.td

 >;
 
 def FeatureFmaMixInsts : SubtargetFeature<"fma-mix-insts",
   "HasFmaMixInsts",
   "true",
   "Has v_fma_mix_f32, v_fma_mixlo_f16, v_fma_mixhi_f16 instructions"
 >;
 
+def FeatureDoesNotSupportXNACK : SubtargetFeature<"no-xnack-support",
+  "DoesNotSupportXNACK",
+  "true",
+  "Hardware does not support XNACK"
+>;
+
 // XNACK is disabled if SH_MEM_CONFIG.ADDRESS_MODE = GPUVM on chips that support
 // XNACK. The current default kernel driver setting is:
 // - graphics ring: XNACK disabled
 // - compute ring: XNACK enabled
 //
 // If XNACK is enabled, the VMEM latency can be worse.
 // If XNACK is disabled, the 2 SGPRs can be used for general purposes.
 def FeatureXNACK : SubtargetFeature<"xnack",

 class GCNSubtargetFeatureGeneration <string Value,
                                   list<SubtargetFeature> Implies> :
         SubtargetFeatureGeneration <Value, "GCNSubtarget", Implies>;
 
 def FeatureSouthernIslands : GCNSubtargetFeatureGeneration<"SOUTHERN_ISLANDS",
   [FeatureFP64, FeatureLocalMemorySize32768, FeatureMIMG_R128,
   FeatureWavefrontSize64,
   FeatureLDSBankCount32, FeatureMovrel, FeatureTrigReducedRange,
-  FeatureDoesNotSupportSRAMECC]
+  FeatureDoesNotSupportSRAMECC, FeatureDoesNotSupportXNACK]
 >;
 
 def FeatureSeaIslands : GCNSubtargetFeatureGeneration<"SEA_ISLANDS",
   [FeatureFP64, FeatureLocalMemorySize65536, FeatureMIMG_R128,
   FeatureWavefrontSize64, FeatureFlatAddressSpace,
   FeatureCIInsts, FeatureMovrel, FeatureTrigReducedRange,
   FeatureDoesNotSupportSRAMECC]
 >;

 class FeatureSet<list<SubtargetFeature> Features_> {
   list<SubtargetFeature> Features = Features_;
 }
 
 def FeatureISAVersion6_0_0 : FeatureSet<[FeatureSouthernIslands,
    FeatureFastFMAF32,
    HalfRate64Ops,
    FeatureLDSBankCount32,
+   FeatureDoesNotSupportXNACK,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion6_0_1 : FeatureSet<
   [FeatureSouthernIslands,
    FeatureLDSBankCount32,
+   FeatureDoesNotSupportXNACK,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion7_0_0 : FeatureSet<
   [FeatureSeaIslands,
    FeatureLDSBankCount32,
+   FeatureDoesNotSupportXNACK,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion7_0_1 : FeatureSet<
   [FeatureSeaIslands,
    HalfRate64Ops,
    FeatureLDSBankCount32,
    FeatureFastFMAF32,
+   FeatureDoesNotSupportXNACK,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion7_0_2 : FeatureSet<
   [FeatureSeaIslands,
    FeatureLDSBankCount16,
    FeatureFastFMAF32,
+   FeatureDoesNotSupportXNACK,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion7_0_3 : FeatureSet<
   [FeatureSeaIslands,
    FeatureLDSBankCount16,
+   FeatureDoesNotSupportXNACK,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion7_0_4 : FeatureSet<
   [FeatureSeaIslands,
    FeatureLDSBankCount32,
+   FeatureDoesNotSupportXNACK,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion8_0_1 : FeatureSet<
   [FeatureVolcanicIslands,
    FeatureFastFMAF32,
    HalfRate64Ops,
    FeatureLDSBankCount32,
    FeatureXNACK,
    FeatureUnpackedD16VMem,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion8_0_2 : FeatureSet<
   [FeatureVolcanicIslands,
    FeatureLDSBankCount32,
    FeatureSGPRInitBug,
    FeatureUnpackedD16VMem,
+   FeatureDoesNotSupportXNACK,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion8_0_3 : FeatureSet<
   [FeatureVolcanicIslands,
    FeatureLDSBankCount32,
    FeatureUnpackedD16VMem,
+   FeatureDoesNotSupportXNACK,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion8_1_0 : FeatureSet<
   [FeatureVolcanicIslands,
    FeatureLDSBankCount16,
    FeatureXNACK,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion9_0_0 : FeatureSet<
   [FeatureGFX9,
    FeatureMadMixInsts,
    FeatureLDSBankCount32,
    FeatureCodeObjectV3,
+   FeatureDoesNotSupportXNACK,
    FeatureDoesNotSupportSRAMECC]>;
 
 def FeatureISAVersion9_0_2 : FeatureSet<
   [FeatureGFX9,
    FeatureMadMixInsts,
    FeatureLDSBankCount32,
    FeatureXNACK,
    FeatureDoesNotSupportSRAMECC,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion9_0_4 : FeatureSet<
   [FeatureGFX9,
    FeatureLDSBankCount32,
    FeatureFmaMixInsts,
+   FeatureDoesNotSupportXNACK,
    FeatureDoesNotSupportSRAMECC,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion9_0_6 : FeatureSet<
   [FeatureGFX9,
    HalfRate64Ops,
    FeatureFmaMixInsts,
    FeatureLDSBankCount32,
    FeatureDLInsts,
    FeatureDot1Insts,
    FeatureDot2Insts,
+   FeatureDoesNotSupportXNACK,
    FeatureCodeObjectV3]>;
 
 def FeatureISAVersion9_0_9 : FeatureSet<
   [FeatureGFX9,
    FeatureMadMixInsts,
    FeatureLDSBankCount32,
    FeatureXNACK,
    FeatureCodeObjectV3]>;

lib/Target/AMDGPU/AMDGPUSubtarget.h

protected:
   bool FP64FP16Denormals;
   bool FlatForGlobal;
   bool AutoWaitcntBeforeBarrier;
   bool CodeObjectV3;
   bool UnalignedScratchAccess;
   bool UnalignedBufferAccess;
   bool HasApertureRegs;
   bool EnableXNACK;
+  bool DoesNotSupportXNACK;
   bool TrapHandler;
 
   // Used as options.
   bool EnableHugePrivateBuffer;
   bool EnableLoadStoreOpt;
   bool EnableUnsafeDSOffsetFolding;
   bool EnableSIScheduler;
   bool EnableDS128;

lib/Target/AMDGPU/AMDGPUSubtarget.cpp

GCNSubtarget::initializeSubtargetDependencies(const Triple &TT,
   // We want to be able to turn these off, but making this a subtarget feature
   // for SI has the unhelpful behavior that it unsets everything else if you
   // disable it.
   //
   // Similarly we want enable-prt-strict-null to be on by default and not to
   // unset everything else if it is disabled
 
   // Assuming ECC is enabled is the conservative default.
-  SmallString<256> FullFS("+promote-alloca,+load-store-opt,+sram-ecc,");
+  SmallString<256> FullFS("+promote-alloca,+load-store-opt,+sram-ecc,+xnack,");
 
   if (isAmdHsaOS()) // Turn on FlatForGlobal for HSA.
     FullFS += "+flat-for-global,+unaligned-buffer-access,+trap-handler,";
 
   // FIXME: I don't think think Evergreen has any useful support for
   // denormals, but should be checked. Should we issue a warning somewhere
   // if someone tries to enable these?
   if (getGeneration() >= AMDGPUSubtarget::SOUTHERN_ISLANDS) {
GCNSubtarget::initializeSubtargetDependencies(const Triple &TT,
   }
 
   // Don't crash on invalid devices.
   if (WavefrontSize == 0)
     WavefrontSize = 64;
 
   HasFminFmaxLegacy = getGeneration() < AMDGPUSubtarget::VOLCANIC_ISLANDS;
 
+  if (DoesNotSupportXNACK && EnableXNACK) {
+    ToggleFeature(AMDGPU::FeatureXNACK);
+    EnableXNACK = false;
+  }
+
   // ECC is on by default, but turn it off if the hardware doesn't support it
   // anyway. This matters for the gfx9 targets with d16 loads, but don't support
   // ECC.
   if (DoesNotSupportSRAMECC && EnableSRAMECC) {
     ToggleFeature(AMDGPU::FeatureSRAMECC);
     EnableSRAMECC = false;
   }
 
GCNSubtarget::GCNSubtarget(const Triple &TT, StringRef GPU, StringRef FS,
     FlatForGlobal(false),
     AutoWaitcntBeforeBarrier(false),
     CodeObjectV3(false),
     UnalignedScratchAccess(false),
     UnalignedBufferAccess(false),
 
     HasApertureRegs(false),
     EnableXNACK(false),
+    DoesNotSupportXNACK(false),
     TrapHandler(false),
 
     EnableHugePrivateBuffer(false),
     EnableLoadStoreOpt(false),
     EnableUnsafeDSOffsetFolding(false),
     EnableSIScheduler(false),
     EnableDS128(false),
     EnablePRTStrictNull(false),

test/Transforms/Inline/AMDGPU/inline-target-feature-xnack.ll

+; RUN: opt -mtriple=amdgcn-amd-amdhsa -S -inline < %s | FileCheck %s
+; RUN: opt -mtriple=amdgcn-amd-amdhsa -S -passes='cgscc(inline)' < %s | FileCheck %s
+
+define i32 @func_default() #0 {
+  ret i32 0
+}
+
+define i32 @func_xnack_enabled() #1 {
+  ret i32 0
+}
+
+define i32 @func_xnack_disabled() #2 {
+  ret i32 0
+}
+
+; CHECK-LABEL: @default_call_default(
+; CHECK-NEXT: ret i32 0
+define i32 @default_call_default() #0 {
+  %call = call i32 @func_default()
+  ret i32 %call
+}
+
+; CHECK-LABEL: @xnack_enabled_call_default(
+; CHECK-NEXT: ret i32 0
+define i32 @xnack_enabled_call_default() #1 {
+  %call = call i32 @func_default()
+  ret i32 %call
+}
+
+; CHECK-LABEL: @xnack_enabled_call_xnack_enabled(
+; CHECK-NEXT: ret i32 0
+define i32 @xnack_enabled_call_xnack_enabled() #1 {
+  %call = call i32 @func_xnack_enabled()
+  ret i32 %call
+}
+
+; CHECK-LABEL: @xnack_enabled_call_xnack_disabled(
+; CHECK-NEXT: ret i32 0
+define i32 @xnack_enabled_call_xnack_disabled() #1 {
+  %call = call i32 @func_xnack_disabled()
+  ret i32 %call
+}
+
+; CHECK-LABEL: @xnack_disabled_call_default(
+; CHECK-NEXT: ret i32 0
+define i32 @xnack_disabled_call_default() #2 {
+  %call = call i32 @func_default()
+  ret i32 %call
+}
+
+; CHECK-LABEL: @xnack_disabled_call_xnack_enabled(
+; CHECK-NEXT: ret i32 0
+define i32 @xnack_disabled_call_xnack_enabled() #2 {
+  %call = call i32 @func_xnack_enabled()
+  ret i32 %call
+}
+
+; CHECK-LABEL: @xnack_disabled_call_xnack_disabled(
+; CHECK-NEXT: ret i32 0
+define i32 @xnack_disabled_call_xnack_disabled() #2 {
+  %call = call i32 @func_xnack_disabled()
+  ret i32 %call
+}
+
+attributes #0 = { nounwind }
+attributes #1 = { nounwind "target-features"="+xnack" }
+attributes #2 = { nounwind "target-features"="-xnack" }