Index: llvm/lib/Target/AMDGPU/AMDGPUFeatures.td
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUFeatures.td
+++ llvm/lib/Target/AMDGPU/AMDGPUFeatures.td
@@ -29,16 +29,16 @@
 def FeatureLocalMemorySize32768 : SubtargetFeatureLocalMemorySize<32768>;
 def FeatureLocalMemorySize65536 : SubtargetFeatureLocalMemorySize<65536>;
 
-class SubtargetFeatureWavefrontSize <int Value> : SubtargetFeature<
+class SubtargetFeatureWavefrontSize <int Value, int ValueLog2> : SubtargetFeature<
   "wavefrontsize"#Value,
-  "WavefrontSize",
-  !cast<string>(Value),
+  "WavefrontSizeLog2",
+  !cast<string>(ValueLog2),
   "The number of threads per wavefront"
 >;
 
-def FeatureWavefrontSize16 : SubtargetFeatureWavefrontSize<16>;
-def FeatureWavefrontSize32 : SubtargetFeatureWavefrontSize<32>;
-def FeatureWavefrontSize64 : SubtargetFeatureWavefrontSize<64>;
+def FeatureWavefrontSize16 : SubtargetFeatureWavefrontSize<16, 4>;
+def FeatureWavefrontSize32 : SubtargetFeatureWavefrontSize<32, 5>;
+def FeatureWavefrontSize64 : SubtargetFeatureWavefrontSize<64, 6>;
 
 class SubtargetFeatureGeneration <string Value, string FeatureName,
                                  string Subtarget,
Index: llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h
+++ llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h
@@ -77,7 +77,7 @@
   bool HasTrigReducedRange;
   unsigned MaxWavesPerEU;
   int LocalMemorySize;
-  unsigned WavefrontSize;
+  char WavefrontSizeLog2;
 
 public:
   AMDGPUSubtarget(const Triple &TT);
@@ -181,7 +181,11 @@
   }
 
   unsigned getWavefrontSize() const {
-    return WavefrontSize;
+    return 1 << WavefrontSizeLog2;
+  }
+
+  unsigned getWavefrontSizeLog2() const {
+    return WavefrontSizeLog2;
   }
 
   int getLocalMemorySize() const {
@@ -237,8 +241,8 @@
   /// \returns Corresponsing DWARF register number mapping flavour for the
   /// \p WavefrontSize.
   AMDGPUDwarfFlavour getAMDGPUDwarfFlavour() const {
-    return WavefrontSize == 32 ? AMDGPUDwarfFlavour::Wave32
-                               : AMDGPUDwarfFlavour::Wave64;
+    return getWavefrontSize() == 32 ? AMDGPUDwarfFlavour::Wave32
+                                    : AMDGPUDwarfFlavour::Wave64;
   }
 
   virtual ~AMDGPUSubtarget() {}
@@ -454,10 +458,6 @@
     return (Generation)Gen;
   }
 
-  unsigned getWavefrontSizeLog2() const {
-    return Log2_32(WavefrontSize);
-  }
-
   /// Return the number of high bits known to be zero fror a frame index.
   unsigned getKnownHighZeroBitsForFrameIndex() const {
     return countLeadingZeros(MaxWaveScratchSize) + getWavefrontSizeLog2();
@@ -1160,7 +1160,7 @@
       const override;
 
   bool isWave32() const {
-    return WavefrontSize == 32;
+    return getWavefrontSize() == 32;
   }
 
   const TargetRegisterClass *getBoolRC() const {
Index: llvm/lib/Target/AMDGPU/AMDGPUSubtarget.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUSubtarget.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPUSubtarget.cpp
@@ -126,8 +126,8 @@
   }
 
   // Don't crash on invalid devices.
-  if (WavefrontSize == 0)
-    WavefrontSize = 64;
+  if (WavefrontSizeLog2 == 0)
+    WavefrontSizeLog2 = 5;
 
   HasFminFmaxLegacy = getGeneration() < AMDGPUSubtarget::VOLCANIC_ISLANDS;
 
@@ -163,7 +163,7 @@
   HasTrigReducedRange(false),
   MaxWavesPerEU(10),
   LocalMemorySize(0),
-  WavefrontSize(0)
+  WavefrontSizeLog2(0)
   { }
 
 GCNSubtarget::GCNSubtarget(const Triple &TT, StringRef GPU, StringRef FS,