[llvm] [AMDGPU] Select v_lshl_add_u32 instead of v_mul_lo_u32 by constant (PR #71035)

[Jay Foad via llvm-commits]

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@@ -515,6 +515,16 @@ def VOP3_CVT_SR_F8_F32_Profile : VOP3_Profile<VOPProfile<[i32, f32, i32, f32]>,
   let HasExtVOP3DPP = 0;
 }
 
+def IsPow2_32: PatLeaf<(i32 imm), [{
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jayfoad wrote:

Needs a better name, maybe `IsPow2Plus1`

https://github.com/llvm/llvm-project/pull/71035