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AMDGPU: wave_barrier is not isBarrier
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Authored by arsenm on Mar 26 2019, 2:22 PM.

Reviewers

Summary

This is not a control flow instruction, so should not be marked as
isBarrier. This fixes a verifier error if followed by unreachable.

What if we call a real barrier in the same situation?

In D59846#1443708, @rampitec wrote:

What if we call a real barrier in the same situation?

s_barrier already has the correct flags

LGTM

This revision is now accepted and ready to land.Mar 26 2019, 2:48 PM

r357081

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lib/

Target/

AMDGPU/

1 line

test/

CodeGen/

AMDGPU/

12 lines

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	def WAVE_BARRIER : SPseudoInstSI<(outs), (ins),			def WAVE_BARRIER : SPseudoInstSI<(outs), (ins),
	[(int_amdgcn_wave_barrier)]> {			[(int_amdgcn_wave_barrier)]> {
	let SchedRW = [];			let SchedRW = [];
	let hasNoSchedulingInfo = 1;			let hasNoSchedulingInfo = 1;
	let hasSideEffects = 1;			let hasSideEffects = 1;
	let mayLoad = 1;			let mayLoad = 1;
	let mayStore = 1;			let mayStore = 1;
	let isBarrier = 1;
	let isConvergent = 1;			let isConvergent = 1;
	let FixedSize = 1;			let FixedSize = 1;
	let Size = 0;			let Size = 0;
	}			}

	// SI pseudo instructions. These are used by the CFG structurizer pass			// SI pseudo instructions. These are used by the CFG structurizer pass
	// and should be lowered to ISA instructions prior to codegen.			// and should be lowered to ISA instructions prior to codegen.

	▲ Show 20 Lines • Show All 1,522 Lines • Show Last 20 Lines

	; RUN: llc -march=amdgcn -verify-machineinstrs < %s \| FileCheck -check-prefix=GCN %s			; RUN: llc -march=amdgcn -verify-machineinstrs < %s \| FileCheck -check-prefix=GCN %s

	; GCN-LABEL: {{^}}test_wave_barrier:			; GCN-LABEL: {{^}}test_wave_barrier:
	; GCN-DAG: ; wave barrier			; GCN-DAG: ; wave barrier
	; GCN-NOT: s_barrier			; GCN-NOT: s_barrier

	define amdgpu_kernel void @test_wave_barrier() #0 {			define amdgpu_kernel void @test_wave_barrier() #0 {
	entry:			entry:
	call void @llvm.amdgcn.wave.barrier() #1			call void @llvm.amdgcn.wave.barrier() #1
	ret void			ret void
	}			}

				; Check for verifier error from interpreting wave_barrier as a control
				; flow barrier.

				; GCN-LABEL: {{^}}test_wave_barrier_is_not_isBarrier:
				; GCN-DAG: ; wave barrier
				; GCN-NOT: s_barrier
				define amdgpu_kernel void @test_wave_barrier_is_not_isBarrier() #0 {
				entry:
				call void @llvm.amdgcn.wave.barrier() #1
				unreachable
				}

	declare void @llvm.amdgcn.wave.barrier() #1			declare void @llvm.amdgcn.wave.barrier() #1

	attributes #0 = { nounwind }			attributes #0 = { nounwind }
	attributes #1 = { convergent nounwind }			attributes #1 = { convergent nounwind }