AMDGPU: Implement computeKnownBitsForTargetNode for mbcnt

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@318100 91177308-0d34-0410-b5e6-96231b3b80d8
baberthal · Nov 13, 2017 · 12d09b0 · 12d09b0
1 parent 438d60f
commit 12d09b0
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Showing 4 changed files with 38 additions and 2 deletions.
diff --git a/lib/Target/AMDGPU/AMDGPUISelLowering.cpp b/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
@@ -4084,6 +4084,20 @@ void AMDGPUTargetLowering::computeKnownBitsForTargetNode(
       Known.Zero.setHighBits(32 - MaxValBits);
     break;
   }
+  case ISD::INTRINSIC_WO_CHAIN: {
+    unsigned IID = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
+    switch (IID) {
+    case Intrinsic::amdgcn_mbcnt_lo:
+    case Intrinsic::amdgcn_mbcnt_hi: {
+      // These return at most the wavefront size - 1.
+      unsigned Size = Op.getValueType().getSizeInBits();
+      Known.Zero.setHighBits(Size - Subtarget->getWavefrontSizeLog2());
+      break;
+    }
+    default:
+      break;
+    }
+  }
   }
 }
 

diff --git a/lib/Target/AMDGPU/AMDGPUSubtarget.h b/lib/Target/AMDGPU/AMDGPUSubtarget.h
@@ -228,6 +228,10 @@ class AMDGPUSubtarget : public AMDGPUGenSubtargetInfo {
     return WavefrontSize;
   }
 
+  unsigned getWavefrontSizeLog2() const {
+    return Log2_32(WavefrontSize);
+  }
+
   int getLocalMemorySize() const {
     return LocalMemorySize;
   }

diff --git a/test/CodeGen/AMDGPU/array-ptr-calc-i64.ll b/test/CodeGen/AMDGPU/array-ptr-calc-i64.ll
@@ -4,8 +4,8 @@ declare i32 @llvm.amdgcn.mbcnt.lo(i32, i32) #0
 declare i32 @llvm.amdgcn.mbcnt.hi(i32, i32) #0
 
 ; SI-LABEL: {{^}}test_array_ptr_calc:
-; SI-DAG: v_mul_lo_i32
-; SI-DAG: v_mul_hi_i32
+; SI-DAG: v_mul_u32_u24
+; SI-DAG: v_mul_hi_u32_u24
 ; SI: s_endpgm
 define amdgpu_kernel void @test_array_ptr_calc(i32 addrspace(1)* noalias %out, [1025 x i32] addrspace(1)* noalias %inA, i32 addrspace(1)* noalias %inB) {
   %mbcnt.lo = call i32 @llvm.amdgcn.mbcnt.lo(i32 -1, i32 0)

diff --git a/test/CodeGen/AMDGPU/llvm.amdgcn.mbcnt.ll b/test/CodeGen/AMDGPU/llvm.amdgcn.mbcnt.ll
@@ -14,6 +14,24 @@ main_body:
   ret void
 }
 
+; GCN-LABEL: {{^}}mbcnt_lo_known_bits:
+; GCN: v_mbcnt_lo_u32_b32
+; GCN-NOT: and
+define i32 @mbcnt_lo_known_bits(i32 %x, i32 %y) #0 {
+  %lo = call i32 @llvm.amdgcn.mbcnt.lo(i32 %x, i32 %y)
+  %mask = and i32 %lo, 63
+  ret i32 %mask
+}
+
+; GCN-LABEL: {{^}}mbcnt_hi_known_bits:
+; GCN: v_mbcnt_hi_u32_b32
+; GCN-NOT: and
+define i32 @mbcnt_hi_known_bits(i32 %x, i32 %y) #0 {
+  %hi = call i32 @llvm.amdgcn.mbcnt.hi(i32 %x, i32 %y)
+  %mask = and i32 %hi, 63
+  ret i32 %mask
+}
+
 declare i32 @llvm.amdgcn.mbcnt.lo(i32, i32) #0
 declare i32 @llvm.amdgcn.mbcnt.hi(i32, i32) #0
 declare void @llvm.amdgcn.exp.f32(i32, i32, float, float, float, float, i1, i1) #1