AMDGPU: Rewrite SILowerI1Copies to always stay on SALU
Summary:
Instead of writing boolean values temporarily into 32-bit VGPRs
if they are involved in PHIs or are observed from outside a loop,
we use bitwise masking operations to combine lane masks in a way
that is consistent with wave control flow.
Move SIFixSGPRCopies to before this pass, since that pass
incorrectly attempts to move SGPR phis to VGPRs.
This should recover most of the code quality that was lost with
the bug fix in "AMDGPU: Remove PHI loop condition optimization".
There are still some relevant cases where code quality could be
improved, in particular:
- We often introduce redundant masks with EXEC. Ideally, we'd
have a generic computeKnownBits-like analysis to determine
whether masks are already masked by EXEC, so we can avoid this
masking both here and when lowering uniform control flow.
- The criterion we use to determine whether a def is observed
from outside a loop is conservative: it doesn't check whether
(loop) branch conditions are uniform.
Change-Id: Ibabdb373a7510e426b90deef00f5e16c5d56e64b
Reviewers: arsenm, rampitec, tpr
Subscribers: kzhuravl, jvesely, wdng, mgorny, yaxunl, dstuttard, t-tye, eraman, llvm-commits
Differential Revision: https://reviews.llvm.org/D53496
llvm-svn: 345719
2018-10-31 21:27:08 +08:00
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; RUN: llc < %s -march=amdgcn -mcpu=verde -verify-machineinstrs | FileCheck --check-prefix=SI --check-prefix=FUNC %s
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; RUN: llc < %s -march=amdgcn -mcpu=tonga -mattr=-flat-for-global -verify-machineinstrs | FileCheck --check-prefix=SI --check-prefix=FUNC %s
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2015-04-14 22:36:45 +08:00
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; FUNC-LABEL: {{^}}break_inserted_outside_of_loop:
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; SI: [[LOOP_LABEL:[A-Z0-9]+]]:
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; Lowered break instructin:
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; SI: s_or_b64
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; Lowered Loop instruction:
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; SI: s_andn2_b64
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; s_cbranch_execnz [[LOOP_LABEL]]
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; SI: s_endpgm
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2017-03-22 05:39:51 +08:00
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define amdgpu_kernel void @break_inserted_outside_of_loop(i32 addrspace(1)* %out, i32 %a) {
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2015-04-14 22:36:45 +08:00
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main_body:
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2016-02-13 07:45:29 +08:00
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%tid = call i32 @llvm.amdgcn.mbcnt.lo(i32 -1, i32 0) #0
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%0 = and i32 %a, %tid
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2015-04-14 22:36:45 +08:00
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%1 = trunc i32 %0 to i1
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br label %ENDIF
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ENDLOOP:
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store i32 0, i32 addrspace(1)* %out
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ret void
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ENDIF:
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br i1 %1, label %ENDLOOP, label %ENDIF
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}
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2015-05-01 11:44:08 +08:00
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; FUNC-LABEL: {{^}}phi_cond_outside_loop:
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AMDGPU: Rewrite SILowerI1Copies to always stay on SALU
Summary:
Instead of writing boolean values temporarily into 32-bit VGPRs
if they are involved in PHIs or are observed from outside a loop,
we use bitwise masking operations to combine lane masks in a way
that is consistent with wave control flow.
Move SIFixSGPRCopies to before this pass, since that pass
incorrectly attempts to move SGPR phis to VGPRs.
This should recover most of the code quality that was lost with
the bug fix in "AMDGPU: Remove PHI loop condition optimization".
There are still some relevant cases where code quality could be
improved, in particular:
- We often introduce redundant masks with EXEC. Ideally, we'd
have a generic computeKnownBits-like analysis to determine
whether masks are already masked by EXEC, so we can avoid this
masking both here and when lowering uniform control flow.
- The criterion we use to determine whether a def is observed
from outside a loop is conservative: it doesn't check whether
(loop) branch conditions are uniform.
Change-Id: Ibabdb373a7510e426b90deef00f5e16c5d56e64b
Reviewers: arsenm, rampitec, tpr
Subscribers: kzhuravl, jvesely, wdng, mgorny, yaxunl, dstuttard, t-tye, eraman, llvm-commits
Differential Revision: https://reviews.llvm.org/D53496
llvm-svn: 345719
2018-10-31 21:27:08 +08:00
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; SI: s_mov_b64 [[LEFT:s\[[0-9]+:[0-9]+\]]], 0
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; SI: s_mov_b64 [[PHI:s\[[0-9]+:[0-9]+\]]], 0
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2015-05-01 11:44:08 +08:00
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AMDGPU: Rewrite SILowerI1Copies to always stay on SALU
Summary:
Instead of writing boolean values temporarily into 32-bit VGPRs
if they are involved in PHIs or are observed from outside a loop,
we use bitwise masking operations to combine lane masks in a way
that is consistent with wave control flow.
Move SIFixSGPRCopies to before this pass, since that pass
incorrectly attempts to move SGPR phis to VGPRs.
This should recover most of the code quality that was lost with
the bug fix in "AMDGPU: Remove PHI loop condition optimization".
There are still some relevant cases where code quality could be
improved, in particular:
- We often introduce redundant masks with EXEC. Ideally, we'd
have a generic computeKnownBits-like analysis to determine
whether masks are already masked by EXEC, so we can avoid this
masking both here and when lowering uniform control flow.
- The criterion we use to determine whether a def is observed
from outside a loop is conservative: it doesn't check whether
(loop) branch conditions are uniform.
Change-Id: Ibabdb373a7510e426b90deef00f5e16c5d56e64b
Reviewers: arsenm, rampitec, tpr
Subscribers: kzhuravl, jvesely, wdng, mgorny, yaxunl, dstuttard, t-tye, eraman, llvm-commits
Differential Revision: https://reviews.llvm.org/D53496
llvm-svn: 345719
2018-10-31 21:27:08 +08:00
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; SI: ; %else
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; SI: v_cmp_eq_u32_e64 [[TMP:s\[[0-9]+:[0-9]+\]]],
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; SI: ; %endif
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; SI: [[LOOP_LABEL:BB[0-9]+_[0-9]+]]: ; %loop
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; SI: s_and_b64 [[TMP1:s\[[0-9]+:[0-9]+\]]], exec, [[PHI]]
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2019-11-19 01:06:48 +08:00
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; SI: s_or_b64 [[LEFT]], [[TMP1]], [[LEFT]]
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AMDGPU: Rewrite SILowerI1Copies to always stay on SALU
Summary:
Instead of writing boolean values temporarily into 32-bit VGPRs
if they are involved in PHIs or are observed from outside a loop,
we use bitwise masking operations to combine lane masks in a way
that is consistent with wave control flow.
Move SIFixSGPRCopies to before this pass, since that pass
incorrectly attempts to move SGPR phis to VGPRs.
This should recover most of the code quality that was lost with
the bug fix in "AMDGPU: Remove PHI loop condition optimization".
There are still some relevant cases where code quality could be
improved, in particular:
- We often introduce redundant masks with EXEC. Ideally, we'd
have a generic computeKnownBits-like analysis to determine
whether masks are already masked by EXEC, so we can avoid this
masking both here and when lowering uniform control flow.
- The criterion we use to determine whether a def is observed
from outside a loop is conservative: it doesn't check whether
(loop) branch conditions are uniform.
Change-Id: Ibabdb373a7510e426b90deef00f5e16c5d56e64b
Reviewers: arsenm, rampitec, tpr
Subscribers: kzhuravl, jvesely, wdng, mgorny, yaxunl, dstuttard, t-tye, eraman, llvm-commits
Differential Revision: https://reviews.llvm.org/D53496
llvm-svn: 345719
2018-10-31 21:27:08 +08:00
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; SI: s_andn2_b64 exec, exec, [[LEFT]]
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; SI: s_cbranch_execnz [[LOOP_LABEL]]
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; SI: s_endpgm
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2015-05-01 11:44:08 +08:00
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2017-03-22 05:39:51 +08:00
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define amdgpu_kernel void @phi_cond_outside_loop(i32 %b) {
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2015-05-01 11:44:08 +08:00
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entry:
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2016-02-13 07:45:29 +08:00
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%tid = call i32 @llvm.amdgcn.mbcnt.lo(i32 -1, i32 0) #0
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%0 = icmp eq i32 %tid , 0
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2015-05-01 11:44:08 +08:00
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br i1 %0, label %if, label %else
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if:
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br label %endif
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else:
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%1 = icmp eq i32 %b, 0
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br label %endif
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endif:
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%2 = phi i1 [0, %if], [%1, %else]
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br label %loop
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loop:
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br i1 %2, label %exit, label %loop
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exit:
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ret void
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}
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2016-02-13 07:45:29 +08:00
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2016-06-24 14:58:01 +08:00
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; FIXME: should emit s_endpgm
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; CHECK-LABEL: {{^}}switch_unreachable:
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; CHECK-NOT: s_endpgm
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; CHECK: .Lfunc_end2
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2017-03-22 05:39:51 +08:00
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define amdgpu_kernel void @switch_unreachable(i32 addrspace(1)* %g, i8 addrspace(3)* %l, i32 %x) nounwind {
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2016-06-24 14:58:01 +08:00
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centry:
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switch i32 %x, label %sw.default [
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i32 0, label %sw.bb
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i32 60, label %sw.bb
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]
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sw.bb:
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unreachable
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sw.default:
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unreachable
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sw.epilog:
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ret void
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}
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declare float @llvm.fabs.f32(float) nounwind readnone
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; This broke the old AMDIL cfg structurizer
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; FUNC-LABEL: {{^}}loop_land_info_assert:
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2018-06-30 00:26:53 +08:00
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; SI: v_cmp_lt_i32_e64 [[CMP4:s\[[0-9:]+\]]], s{{[0-9]+}}, 4{{$}}
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AMDGPU: Rewrite SILowerI1Copies to always stay on SALU
Summary:
Instead of writing boolean values temporarily into 32-bit VGPRs
if they are involved in PHIs or are observed from outside a loop,
we use bitwise masking operations to combine lane masks in a way
that is consistent with wave control flow.
Move SIFixSGPRCopies to before this pass, since that pass
incorrectly attempts to move SGPR phis to VGPRs.
This should recover most of the code quality that was lost with
the bug fix in "AMDGPU: Remove PHI loop condition optimization".
There are still some relevant cases where code quality could be
improved, in particular:
- We often introduce redundant masks with EXEC. Ideally, we'd
have a generic computeKnownBits-like analysis to determine
whether masks are already masked by EXEC, so we can avoid this
masking both here and when lowering uniform control flow.
- The criterion we use to determine whether a def is observed
from outside a loop is conservative: it doesn't check whether
(loop) branch conditions are uniform.
Change-Id: Ibabdb373a7510e426b90deef00f5e16c5d56e64b
Reviewers: arsenm, rampitec, tpr
Subscribers: kzhuravl, jvesely, wdng, mgorny, yaxunl, dstuttard, t-tye, eraman, llvm-commits
Differential Revision: https://reviews.llvm.org/D53496
llvm-svn: 345719
2018-10-31 21:27:08 +08:00
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; SI: s_and_b64 [[CMP4M:s\[[0-9]+:[0-9]+\]]], exec, [[CMP4]]
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2019-08-30 03:03:58 +08:00
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; SI: [[WHILELOOP:BB[0-9]+_[0-9]+]]: ; %while.cond
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; SI: s_cbranch_vccz [[FOR_COND_PH:BB[0-9]+_[0-9]+]]
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2019-01-26 03:45:13 +08:00
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; SI: [[CONVEX_EXIT:BB[0-9_]+]]
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; SI: s_mov_b64 vcc,
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; SI-NEXT: s_cbranch_vccnz [[ENDPGM:BB[0-9]+_[0-9]+]]
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2019-08-30 03:03:58 +08:00
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; SI: s_cbranch_vccnz [[WHILELOOP]]
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AMDGPU: Rewrite SILowerI1Copies to always stay on SALU
Summary:
Instead of writing boolean values temporarily into 32-bit VGPRs
if they are involved in PHIs or are observed from outside a loop,
we use bitwise masking operations to combine lane masks in a way
that is consistent with wave control flow.
Move SIFixSGPRCopies to before this pass, since that pass
incorrectly attempts to move SGPR phis to VGPRs.
This should recover most of the code quality that was lost with
the bug fix in "AMDGPU: Remove PHI loop condition optimization".
There are still some relevant cases where code quality could be
improved, in particular:
- We often introduce redundant masks with EXEC. Ideally, we'd
have a generic computeKnownBits-like analysis to determine
whether masks are already masked by EXEC, so we can avoid this
masking both here and when lowering uniform control flow.
- The criterion we use to determine whether a def is observed
from outside a loop is conservative: it doesn't check whether
(loop) branch conditions are uniform.
Change-Id: Ibabdb373a7510e426b90deef00f5e16c5d56e64b
Reviewers: arsenm, rampitec, tpr
Subscribers: kzhuravl, jvesely, wdng, mgorny, yaxunl, dstuttard, t-tye, eraman, llvm-commits
Differential Revision: https://reviews.llvm.org/D53496
llvm-svn: 345719
2018-10-31 21:27:08 +08:00
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; SI: ; %if.else
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; SI: buffer_store_dword
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2018-06-30 00:26:53 +08:00
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2019-08-30 03:03:58 +08:00
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; SI: [[FOR_COND_PH]]: ; %for.cond.preheader
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2018-06-30 00:26:53 +08:00
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; SI: s_cbranch_vccz [[ENDPGM]]
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; SI: [[ENDPGM]]:
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; SI-NEXT: s_endpgm
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2017-03-22 05:39:51 +08:00
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define amdgpu_kernel void @loop_land_info_assert(i32 %c0, i32 %c1, i32 %c2, i32 %c3, i32 %x, i32 %y, i1 %arg) nounwind {
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2016-06-24 14:58:01 +08:00
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entry:
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%cmp = icmp sgt i32 %c0, 0
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br label %while.cond.outer
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while.cond.outer:
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%tmp = load float, float addrspace(1)* undef
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br label %while.cond
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while.cond:
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%cmp1 = icmp slt i32 %c1, 4
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br i1 %cmp1, label %convex.exit, label %for.cond
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convex.exit:
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%or = or i1 %cmp, %cmp1
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br i1 %or, label %return, label %if.end
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if.end:
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%tmp3 = call float @llvm.fabs.f32(float %tmp) nounwind readnone
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%cmp2 = fcmp olt float %tmp3, 0x3E80000000000000
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br i1 %cmp2, label %if.else, label %while.cond.outer
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if.else:
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store volatile i32 3, i32 addrspace(1)* undef, align 4
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br label %while.cond
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for.cond:
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%cmp3 = icmp slt i32 %c3, 1000
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br i1 %cmp3, label %for.body, label %return
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for.body:
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br i1 %cmp3, label %self.loop, label %if.end.2
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if.end.2:
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%or.cond2 = or i1 %cmp3, %arg
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br i1 %or.cond2, label %return, label %for.cond
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self.loop:
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br label %self.loop
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return:
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ret void
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}
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2016-02-13 07:45:29 +08:00
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declare i32 @llvm.amdgcn.mbcnt.lo(i32, i32) #0
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attributes #0 = { nounwind readnone }
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