[AMDGPU][GFX9] Set +fp32-denormals for >=gfx900 unless -cl-denorms-are-zero is set

[arsenm]

llvm/tools/clang/lib/Basic/Targets.cpp

2114–2116 ↗

(On Diff #93420)

This is misleading since it was true on VI as well. I think just FMA rate changed

[kzhuravl]

llvm/tools/clang/lib/Basic/Targets.cpp

2114–2116 ↗

(On Diff #93420)

Yes, GFX8 supports f32 denorms at full speed too. However, it doesn't have a full speed fma, so we didh't enable it then since it caused too many mad-heavy apps to slow down.

[arsenm]

llvm/tools/clang/lib/Basic/Targets.cpp

2114–2116 ↗

(On Diff #93420)

Yes, so the name should refer to FMA rather than just fp32 denorms

[kzhuravl]

Address review feedback.

[arsenm]

LGTM with f32 clarification

lib/Basic/Targets.cpp

2114 ↗

(On Diff #93422)

FMAF32?

2115 ↗

(On Diff #93422)

We should probably add a new subtarget feature for this, but that's a separate patch

[arsenm]

lib/Basic/Targets.cpp

2114 ↗

(On Diff #93422)

Actually this also needs to specify full speed FMA with denorms. Full rate FMA is already a subtarget feature when denorms are disabled

[kzhuravl]

lib/Basic/Targets.cpp

2114 ↗

(On Diff #93422)

I will do it in a separate patch. Thanks.

cfe/trunk/lib/Basic/Targets.cpp

enum GPUKind {
     GK_GFX7,
     GK_GFX8,
     GK_GFX9
   } GPU;
 
   bool hasFP64:1;
   bool hasFMAF:1;
   bool hasLDEXPF:1;
-  bool hasFullSpeedFP32Denorms:1;
   const AddrSpace AS;
 
+  static bool hasFullSpeedFMAF32(StringRef GPUName) {
+    return parseAMDGCNName(GPUName) >= GK_GFX9;
+  }
+
   static bool isAMDGCN(const llvm::Triple &TT) {
     return TT.getArch() == llvm::Triple::amdgcn;
   }
 
   static bool isGenericZero(const llvm::Triple &TT) {
     return TT.getEnvironmentName() == "amdgiz" ||
         TT.getEnvironmentName() == "amdgizcl";
   }
 public:
   AMDGPUTargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
     : TargetInfo(Triple) ,
       GPU(isAMDGCN(Triple) ? GK_GFX6 : GK_R600),
       hasFP64(false),
       hasFMAF(false),
       hasLDEXPF(false),
-      hasFullSpeedFP32Denorms(false),
       AS(isGenericZero(Triple)){
     if (getTriple().getArch() == llvm::Triple::amdgcn) {
       hasFP64 = true;
       hasFMAF = true;
       hasLDEXPF = true;
     }
     auto IsGenericZero = isGenericZero(Triple);
     resetDataLayout(getTriple().getArch() == llvm::Triple::amdgcn ?
void adjustTargetOptions(const CodeGenOptions &CGOpts,
     bool hasFP64Denormals = false;
     for (auto &I : TargetOpts.FeaturesAsWritten) {
       if (I == "+fp32-denormals" || I == "-fp32-denormals")
         hasFP32Denormals = true;
       if (I == "+fp64-fp16-denormals" || I == "-fp64-fp16-denormals")
         hasFP64Denormals = true;
     }
     if (!hasFP32Denormals)
-      TargetOpts.Features.push_back((Twine(hasFullSpeedFP32Denorms &&
+      TargetOpts.Features.push_back(
+          (Twine(hasFullSpeedFMAF32(TargetOpts.CPU) &&
           !CGOpts.FlushDenorm ? '+' : '-') + Twine("fp32-denormals")).str());
     // Always do not flush fp64 or fp16 denorms.
     if (!hasFP64Denormals && hasFP64)
       TargetOpts.Features.push_back("+fp64-fp16-denormals");
   }
 
   ArrayRef<Builtin::Info> getTargetBuiltins() const override {
     return llvm::makeArrayRef(BuiltinInfo,

cfe/trunk/test/CodeGenOpenCL/gfx9-fp32-denorms.cl

+// REQUIRES: amdgpu-registered-target
+
+// RUN: %clang_cc1 -triple amdgcn-unknown-unknown -target-cpu gfx900 -S -emit-llvm -o - %s | FileCheck --check-prefix=DEFAULT %s
+// RUN: %clang_cc1 -triple amdgcn-unknown-unknown -target-cpu gfx900 -S -emit-llvm -o - -target-feature +fp32-denormals %s | FileCheck --check-prefix=FEATURE_FP32_DENORMALS_ON %s
+// RUN: %clang_cc1 -triple amdgcn-unknown-unknown -target-cpu gfx900 -S -emit-llvm -o - -target-feature -fp32-denormals %s | FileCheck --check-prefix=FEATURE_FP32_DENORMALS_OFF %s
+// RUN: %clang_cc1 -triple amdgcn-unknown-unknown -target-cpu gfx900 -S -emit-llvm -o - -cl-denorms-are-zero %s | FileCheck --check-prefix=OPT_DENORMS_ARE_ZERO %s
+
+// DEFAULT: +fp32-denormals
+// FEATURE_FP32_DENORMALS_ON: +fp32-denormals
+// FEATURE_FP32_DENORMALS_OFF: -fp32-denormals
+// OPT_DENORMS_ARE_ZERO: -fp32-denormals
+
+kernel void gfx9_fp32_denorms() {}