04fff547e2
Currently the return address ABI registers s[30:31], which fall in the call clobbered register range, are added as a live-in on the function entry to preserve its value when we have calls so that it gets saved and restored around the calls. But the DWARF unwind information (CFI) needs to track where the return address resides in a frame and the above approach makes it difficult to track the return address when the CFI information is emitted during the frame lowering, due to the involvment of understanding the control flow. This patch moves the return address ABI registers s[30:31] into callee saved registers range and stops adding live-in for return address registers, so that the CFI machinery will know where the return address resides when CSR save/restore happen during the frame lowering. And doing the above poses an issue that now the return instruction uses undefined register `sgpr30_sgpr31`. This is resolved by hiding the return address register use by the return instruction through the `SI_RETURN` pseudo instruction, which doesn't take any input operands, until the `SI_RETURN` pseudo gets lowered to the `S_SETPC_B64_return` during the `expandPostRAPseudo()`. As an added benefit, this patch simplifies overall return instruction handling. Note: The AMDGPU CFI changes are there only in the downstream code and another version of this patch will be posted for review for the downstream code. Reviewed By: arsenm, ronlieb Differential Revision: https://reviews.llvm.org/D114652
62 lines
3.1 KiB
YAML
62 lines
3.1 KiB
YAML
# RUN: not llc -march=amdgcn -mcpu=gfx908 -verify-machineinstrs=0 -start-before=greedy,1 -stop-after=virtregrewriter,1 %s -o /dev/null 2>&1 | FileCheck -check-prefix=ERR %s
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# RUN: not --crash llc -march=amdgcn -mcpu=gfx908 -verify-machineinstrs -start-before=greedy,1 -stop-after=virtregrewriter,1 %s -o /dev/null 2>&1 | FileCheck -check-prefixes=ERR,VERIFIER %s
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# FIXME: We should not produce a verifier error after erroring
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# ERR: error: inline assembly requires more registers than available
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# VERIFIER: *** Bad machine code: Using an undefined physical register ***
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# This testcase cannot be compiled with the enforced register
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# budget. Previously, tryLastChanceRecoloring would assert here. It
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# was attempting to recolor a superregister with an overlapping
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# subregister over the same range.
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--- |
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define void @foo() #0 {
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ret void
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}
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attributes #0 = { "amdgpu-waves-per-eu"="8,8" }
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...
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---
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name: foo
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tracksRegLiveness: true
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registers:
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- { id: 0, class: vgpr_32 }
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- { id: 1, class: vgpr_32 }
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- { id: 2, class: vreg_512 }
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- { id: 3, class: vreg_256 }
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- { id: 4, class: vreg_128 }
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- { id: 5, class: vreg_96 }
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- { id: 6, class: vreg_96 }
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- { id: 7, class: vreg_512 }
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- { id: 8, class: vreg_256 }
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- { id: 9, class: vreg_128 }
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- { id: 10, class: vreg_96 }
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- { id: 11, class: vreg_96 }
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- { id: 12, class: sreg_64 }
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- { id: 13, class: sgpr_64 }
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- { id: 14, class: vgpr_32 }
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machineFunctionInfo:
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scratchRSrcReg: '$sgpr0_sgpr1_sgpr2_sgpr3'
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frameOffsetReg: '$sgpr33'
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stackPtrOffsetReg: '$sgpr32'
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body: |
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bb.0 (%ir-block.0):
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INLINEASM &"; def $0", 1 /* sideeffect attdialect */, 10 /* regdef */, implicit-def $agpr0
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%14:vgpr_32 = COPY killed $agpr0
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INLINEASM &"; def $0 $1 $2 $3 $4", 1 /* sideeffect attdialect */, 11534346 /* regdef:VReg_512 */, def %7, 10158090 /* regdef:VReg_256 */, def %8, 4784138 /* regdef:VReg_128 */, def %9, 3670026 /* regdef:VReg_96 */, def %10, 3670026 /* regdef:VReg_96 */, def %11
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INLINEASM &"; clobber", 1 /* sideeffect attdialect */, 12 /* clobber */, implicit-def dead early-clobber $agpr0_agpr1_agpr2_agpr3_agpr4_agpr5_agpr6_agpr7_agpr8_agpr9_agpr10_agpr11_agpr12_agpr13_agpr14_agpr15_agpr16_agpr17_agpr18_agpr19_agpr20_agpr21_agpr22_agpr23_agpr24_agpr25_agpr26_agpr27_agpr28_agpr29_agpr30_agpr31, 12 /* clobber */, implicit-def dead early-clobber $vgpr0_vgpr1_vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9_vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15_vgpr16_vgpr17_vgpr18_vgpr19_vgpr20_vgpr21_vgpr22_vgpr23_vgpr24_vgpr25_vgpr26_vgpr27_vgpr28_vgpr29_vgpr30_vgpr31
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INLINEASM &"; use $0", 1 /* sideeffect attdialect */, 11534345 /* reguse:VReg_512 */, %7
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INLINEASM &"; use $0", 1 /* sideeffect attdialect */, 10158089 /* reguse:VReg_256 */, %8
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INLINEASM &"; use $0", 1 /* sideeffect attdialect */, 4784137 /* reguse:VReg_128 */, %9
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INLINEASM &"; use $0", 1 /* sideeffect attdialect */, 3670025 /* reguse:VReg_96 */, %10
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INLINEASM &"; use $0", 1 /* sideeffect attdialect */, 3670025 /* reguse:VReg_96 */, %11
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$agpr1 = COPY %14
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INLINEASM &"; use $0", 1 /* sideeffect attdialect */, 9 /* reguse */, killed $agpr1
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SI_RETURN
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...
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