AMDGPU: Implement hasBitPreservingFPLogic

llvm-svn: 315754
diff --git a/llvm/test/CodeGen/AMDGPU/fabs.ll b/llvm/test/CodeGen/AMDGPU/fabs.ll
index 600c6cd..550ad79 100644
--- a/llvm/test/CodeGen/AMDGPU/fabs.ll
+++ b/llvm/test/CodeGen/AMDGPU/fabs.ll
@@ -83,7 +83,7 @@
   ret void
 }
 
-; GCN-LABEL: {{^}}fabs_fold:
+; FUNC-LABEL: {{^}}fabs_fold:
 ; SI: s_load_dword [[ABS_VALUE:s[0-9]+]], s[{{[0-9]+:[0-9]+}}], 0xb
 ; VI: s_load_dword [[ABS_VALUE:s[0-9]+]], s[{{[0-9]+:[0-9]+}}], 0x2c
 ; GCN-NOT: and
@@ -95,6 +95,18 @@
   ret void
 }
 
+; Make sure we turn some integer operations back into fabs
+; FUNC-LABEL: {{^}}bitpreserve_fabs_f32:
+; GCN: v_add_f32_e64 v{{[0-9]+}}, |s{{[0-9]+}}|, 1.0
+define amdgpu_kernel void @bitpreserve_fabs_f32(float addrspace(1)* %out, float %in) {
+  %in.bc = bitcast float %in to i32
+  %int.abs = and i32 %in.bc, 2147483647
+  %bc = bitcast i32 %int.abs to float
+  %fadd = fadd float %bc, 1.0
+  store float %fadd, float addrspace(1)* %out
+  ret void
+}
+
 declare float @fabs(float) readnone
 declare float @llvm.fabs.f32(float) readnone
 declare <2 x float> @llvm.fabs.v2f32(<2 x float>) readnone