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DAG: Use phi in alloca constant case to create virtual registers #130254

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Merged
merged 1 commit into from
Mar 8, 2025
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DAG: Use phi in alloca constant case to create virtual registers #130254

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2 changes: 1 addition & 1 deletion llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12039,7 +12039,7 @@ SelectionDAGBuilder::HandlePHINodesInSuccessorBlocks(const BasicBlock *LLVMBB) {
assert(isa<AllocaInst>(PHIOp) &&
FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(PHIOp)) &&
"Didn't codegen value into a register!??");
Reg = FuncInfo.CreateRegs(PHIOp);
Reg = FuncInfo.CreateRegs(&PN);
CopyValueToVirtualRegister(PHIOp, Reg);
}
}
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49 changes: 49 additions & 0 deletions llvm/test/CodeGen/AMDGPU/copy-to-reg-frameindex.ll
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Expand Up @@ -35,3 +35,52 @@ done:
store i32 %extract.0, ptr addrspace(1) %out, align 4
ret void
}

; When creating registers for %divergent.alloca.phi, we should report
; the CopyToReg as divergent values (not uniform just because the
; alloca is uniform)
define void @phi_with_alloca_and_divergent_copy_to_reg(ptr addrspace(5) %divergent.private, ptr addrspace(1) %out, i32 %a, i32 %b, i32 %c) {
; CHECK-LABEL: phi_with_alloca_and_divergent_copy_to_reg:
; CHECK: ; %bb.0: ; %entry
; CHECK-NEXT: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
; CHECK-NEXT: v_mov_b32_e32 v7, v2
; CHECK-NEXT: v_mov_b32_e32 v6, v1
; CHECK-NEXT: s_mov_b64 s[4:5], 0
; CHECK-NEXT: v_lshrrev_b32_e64 v2, 6, s32
; CHECK-NEXT: .LBB1_1: ; %loop
; CHECK-NEXT: ; =>This Inner Loop Header: Depth=1
; CHECK-NEXT: v_mov_b32_e32 v1, v2
; CHECK-NEXT: v_lshl_add_u32 v2, v3, 2, v1
; CHECK-NEXT: buffer_store_dword v3, v2, s[0:3], 0 offen
; CHECK-NEXT: v_add_u32_e32 v2, 1, v3
; CHECK-NEXT: v_cmp_lt_u32_e32 vcc, 15, v2
; CHECK-NEXT: s_or_b64 s[4:5], vcc, s[4:5]
; CHECK-NEXT: v_mov_b32_e32 v3, v4
; CHECK-NEXT: v_mov_b32_e32 v2, v0
; CHECK-NEXT: s_andn2_b64 exec, exec, s[4:5]
; CHECK-NEXT: s_cbranch_execnz .LBB1_1
; CHECK-NEXT: ; %bb.2: ; %done
; CHECK-NEXT: s_or_b64 exec, exec, s[4:5]
; CHECK-NEXT: buffer_load_dword v0, v1, s[0:3], 0 offen
; CHECK-NEXT: s_waitcnt vmcnt(0)
; CHECK-NEXT: global_store_dword v[6:7], v0, off
; CHECK-NEXT: s_waitcnt vmcnt(0)
; CHECK-NEXT: s_setpc_b64 s[30:31]
entry:
%alloca0 = alloca [16 x i32], addrspace(5)
br label %loop

loop:
%inc = phi i32 [%a, %entry], [%b, %loop]
%divergent.alloca.phi = phi ptr addrspace(5) [ %alloca0, %entry ], [ %divergent.private, %loop ]
%ptr = getelementptr [16 x i32], ptr addrspace(5) %divergent.alloca.phi, i32 0, i32 %inc
store i32 %inc, ptr addrspace(5) %ptr
%inc.i = add i32 %inc, 1
%cnd = icmp uge i32 %inc.i, 16
br i1 %cnd, label %done, label %loop

done:
%tmp1 = load i32, ptr addrspace(5) %divergent.alloca.phi
store i32 %tmp1, ptr addrspace(1) %out
ret void
}