AMDGPU: Disable fp64 support on pre GCN asics

It's not implemented.
Passing +fp64-fp16-denormal feature enables fp64 even on asics that don't support it

v2: fix hasFP64 query

Differential Revision: https://reviews.llvm.org/D39931

llvm-svn: 319709

Author: jvesely

llvm/lib/Target/AMDGPU/AMDGPUSubtarget.cpp

@@ -48,29 +48,34 @@ AMDGPUSubtarget::initializeSubtargetDependencies(const Triple &TT,
   // for SI has the unhelpful behavior that it unsets everything else if you
   // disable it.
 
-  SmallString<256> FullFS("+promote-alloca,+fp64-fp16-denormals,+dx10-clamp,+load-store-opt,");
+  SmallString<256> FullFS("+promote-alloca,+dx10-clamp,+load-store-opt,");
+
   if (isAmdHsaOS()) // Turn on FlatForGlobal for HSA.
     FullFS += "+flat-address-space,+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) {
+    FullFS += "+fp64-fp16-denormals,";
+  } else {
+    FullFS += "-fp32-denormals,";
+  }
+
   FullFS += FS;
 
   ParseSubtargetFeatures(GPU, FullFS);
 
+  // We don't support FP64 for EG/NI atm.
+  assert(!hasFP64() || (getGeneration() >= AMDGPUSubtarget::SOUTHERN_ISLANDS));
+
   // Unless +-flat-for-global is specified, turn on FlatForGlobal for all OS-es
   // on VI and newer hardware to avoid assertion failures due to missing ADDR64
   // variants of MUBUF instructions.
   if (!hasAddr64() && !FS.contains("flat-for-global")) {
     FlatForGlobal = true;
   }
 
-  // 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::NORTHERN_ISLANDS) {
-    FP64FP16Denormals = false;
-    FP32Denormals = false;
-  }
-
   // Set defaults if needed.
   if (MaxPrivateElementSize == 0)
     MaxPrivateElementSize = 4;

llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h

@@ -261,7 +261,7 @@ class AMDGPUSubtarget : public AMDGPUGenSubtargetInfo {
     return HasVOP3PInsts;
   }
 
-  bool hasHWFP64() const {
+  bool hasFP64() const {
     return FP64;
   }
 

llvm/lib/Target/AMDGPU/R600Processors.td

@@ -24,7 +24,7 @@ def : Processor<"rs880", R600_VLIW5_Itin,
 >;
 
 def : Processor<"rv670", R600_VLIW5_Itin,
-  [FeatureR600, FeatureWavefrontSize64, FeatureVertexCache, FeatureFP64]
+  [FeatureR600, FeatureWavefrontSize64, FeatureVertexCache]
 >;
 
 //===----------------------------------------------------------------------===//
@@ -40,7 +40,7 @@ def : Processor<"rv730", R600_VLIW5_Itin,
 >;
 
 def : Processor<"rv770", R600_VLIW5_Itin,
-  [FeatureR700, FeatureWavefrontSize64, FeatureVertexCache, FeatureFP64]
+  [FeatureR700, FeatureWavefrontSize64, FeatureVertexCache]
 >;
 
 //===----------------------------------------------------------------------===//
@@ -53,7 +53,7 @@ def : Processor<"cedar", R600_VLIW5_Itin,
 >;
 
 def : Processor<"cypress", R600_VLIW5_Itin,
-  [FeatureEvergreen, FeatureWavefrontSize64, FeatureVertexCache, FeatureFP64]
+  [FeatureEvergreen, FeatureWavefrontSize64, FeatureVertexCache]
 >;
 
 def : Processor<"juniper", R600_VLIW5_Itin,
@@ -82,7 +82,7 @@ def : Processor<"caicos", R600_VLIW5_Itin,
 >;
 
 def : Processor<"cayman", R600_VLIW4_Itin,
-  [FeatureNorthernIslands, FeatureFP64, FeatureCaymanISA]
+  [FeatureNorthernIslands, FeatureCaymanISA]
 >;
 
 def : Processor<"turks", R600_VLIW5_Itin,

llvm/test/CodeGen/AMDGPU/fma.ll

@@ -1,5 +1,5 @@
 ; RUN:  llc -amdgpu-scalarize-global-loads=false  -march=amdgcn -mcpu=tahiti -verify-machineinstrs < %s | FileCheck -check-prefix=SI -check-prefix=FUNC %s
-; RUN:  llc -amdgpu-scalarize-global-loads=false  -march=r600 -mcpu=cypress -verify-machineinstrs < %s | FileCheck -check-prefix=EG -check-prefix=FUNC %s
+; XUN:  llc -amdgpu-scalarize-global-loads=false  -march=r600 -mcpu=cypress -verify-machineinstrs < %s | FileCheck -check-prefix=EG -check-prefix=FUNC %s
 
 declare float @llvm.fma.f32(float, float, float) nounwind readnone
 declare <2 x float> @llvm.fma.v2f32(<2 x float>, <2 x float>, <2 x float>) nounwind readnone