11b0401926
Currently, the AMDGPU backend bumps the Stack Pointer by fixed size offsets in the prolog of device functions, and restores it by the same amount in the epilog. Prolog: sp += frameSize Epilog: sp -= frameSize If a function has dynamic stack realignment, Prolog: sp += frameSize + max_alignment Epilog: sp -= frameSize + max_alignment These calculations are not optimal in case of dynamic stack realignment, and completely fail in case of dynamic stack readjustment. This patch uses the saved Frame Pointer to restore SP. Prolog: fp = sp sp += frameSize Epilog: sp = fp In case of dynamic stack realignment, SP is restored from the saved Base Pointer. Prolog: fp = sp + (max_alignment - 1) fp = fp & (-max_alignment) bp = sp sp += frameSize + max_alignment Epilog: sp = bp (Note: The presence of BP has been enforced in case of any dynamic stack realignment.) --------- Co-authored-by: Pravin Jagtap <Pravin.Jagtap@amd.com> Co-authored-by: Matt Arsenault <arsenm2@gmail.com>
80 lines
3.8 KiB
LLVM
80 lines
3.8 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
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; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx906 -verify-machineinstrs < %s | FileCheck -check-prefix=GCN %s
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; The custom CSR spills inserted during the frame lowering was earlier using SP as the frame base.
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; The offsets allocated for the CS objects go wrong when any local stack object has a higher
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; alignment requirement than the default stack alignment for AMDGPU (either 4 or 16). The offsets
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; in such cases should be from the newly aligned FP. Even to adjust the offset from the SP value
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; at function entry, the FP-SP can't be statically determined with dynamic stack realignment. To
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; fix the problem, use FP as the frame base in the spills whenever the function has FP.
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define void @test_stack_realign(<8 x i32> %val, i32 %idx) #0 {
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; GCN-LABEL: test_stack_realign:
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; GCN: ; %bb.0:
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; GCN-NEXT: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
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; GCN-NEXT: s_mov_b32 s16, s33
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; GCN-NEXT: s_add_i32 s33, s32, 0xfc0
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; GCN-NEXT: s_and_b32 s33, s33, 0xfffff000
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; GCN-NEXT: s_or_saveexec_b64 s[18:19], -1
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; GCN-NEXT: buffer_store_dword v42, off, s[0:3], s33 offset:96 ; 4-byte Folded Spill
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; GCN-NEXT: s_mov_b64 exec, s[18:19]
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; GCN-NEXT: v_writelane_b32 v42, s16, 2
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; GCN-NEXT: v_writelane_b32 v42, s34, 3
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; GCN-NEXT: s_mov_b32 s34, s32
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; GCN-NEXT: s_addk_i32 s32, 0x3000
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; GCN-NEXT: s_getpc_b64 s[16:17]
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; GCN-NEXT: s_add_u32 s16, s16, extern_func@gotpcrel32@lo+4
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; GCN-NEXT: s_addc_u32 s17, s17, extern_func@gotpcrel32@hi+12
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; GCN-NEXT: s_load_dwordx2 s[16:17], s[16:17], 0x0
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; GCN-NEXT: buffer_store_dword v40, off, s[0:3], s33 offset:4 ; 4-byte Folded Spill
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; GCN-NEXT: buffer_store_dword v41, off, s[0:3], s33 ; 4-byte Folded Spill
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; GCN-NEXT: v_writelane_b32 v42, s30, 0
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; GCN-NEXT: buffer_store_dword v7, off, s[0:3], s33 offset:92
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; GCN-NEXT: s_waitcnt vmcnt(0)
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; GCN-NEXT: buffer_store_dword v6, off, s[0:3], s33 offset:88
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; GCN-NEXT: s_waitcnt vmcnt(0)
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; GCN-NEXT: buffer_store_dword v5, off, s[0:3], s33 offset:84
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; GCN-NEXT: s_waitcnt vmcnt(0)
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; GCN-NEXT: buffer_store_dword v4, off, s[0:3], s33 offset:80
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; GCN-NEXT: s_waitcnt vmcnt(0)
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; GCN-NEXT: buffer_store_dword v3, off, s[0:3], s33 offset:76
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; GCN-NEXT: s_waitcnt vmcnt(0)
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; GCN-NEXT: buffer_store_dword v2, off, s[0:3], s33 offset:72
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; GCN-NEXT: s_waitcnt vmcnt(0)
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; GCN-NEXT: buffer_store_dword v1, off, s[0:3], s33 offset:68
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; GCN-NEXT: s_waitcnt vmcnt(0)
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; GCN-NEXT: buffer_store_dword v0, off, s[0:3], s33 offset:64
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; GCN-NEXT: s_waitcnt vmcnt(0)
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; GCN-NEXT: v_mov_b32_e32 v0, v8
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; GCN-NEXT: v_writelane_b32 v42, s31, 1
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; GCN-NEXT: ;;#ASMSTART
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; GCN-NEXT: ;;#ASMEND
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; GCN-NEXT: ;;#ASMSTART
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; GCN-NEXT: ;;#ASMEND
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; GCN-NEXT: s_waitcnt lgkmcnt(0)
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; GCN-NEXT: s_swappc_b64 s[30:31], s[16:17]
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; GCN-NEXT: buffer_load_dword v41, off, s[0:3], s33 ; 4-byte Folded Reload
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; GCN-NEXT: buffer_load_dword v40, off, s[0:3], s33 offset:4 ; 4-byte Folded Reload
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; GCN-NEXT: v_readlane_b32 s31, v42, 1
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; GCN-NEXT: v_readlane_b32 s30, v42, 0
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; GCN-NEXT: s_mov_b32 s32, s34
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; GCN-NEXT: v_readlane_b32 s4, v42, 2
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; GCN-NEXT: v_readlane_b32 s34, v42, 3
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; GCN-NEXT: s_or_saveexec_b64 s[6:7], -1
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; GCN-NEXT: buffer_load_dword v42, off, s[0:3], s33 offset:96 ; 4-byte Folded Reload
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; GCN-NEXT: s_mov_b64 exec, s[6:7]
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; GCN-NEXT: s_mov_b32 s33, s4
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; GCN-NEXT: s_waitcnt vmcnt(0)
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; GCN-NEXT: s_setpc_b64 s[30:31]
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%alloca.val = alloca <8 x i32>, align 64, addrspace(5)
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store volatile <8 x i32> %val, ptr addrspace(5) %alloca.val, align 64
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call void asm sideeffect "", "~{v40}" ()
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call void asm sideeffect "", "~{v41}" ()
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call void @extern_func(i32 %idx)
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ret void
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}
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declare void @extern_func(i32) #0
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attributes #0 = { noinline nounwind }
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