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[llvm][CodeGen] Update checking method of loop-carried phi in window scheduler #96288

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Jun 26, 2024
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[llvm][CodeGen] Update checking method of loop-carried phi in window scheduler #96288

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[llvm][CodeGen] Update checking method of loop-carried phi in window …
huaatian Jun 21, 2024
b4f725b
[llvm][CodeGen] Modifications made based on review comments 1
huaatian Jun 21, 2024
8bea9bc
[llvm][CodeGen] Modifications made based on review comments 2
huaatian Jun 25, 2024
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31 changes: 20 additions & 11 deletions llvm/lib/CodeGen/WindowScheduler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -192,22 +192,31 @@ bool WindowScheduler::initialize() {
return false;
}
// Check each MI in MBB.
SmallVector<Register, 8> PhiDefs;
SmallSet<Register, 8> PrevDefs;
SmallSet<Register, 8> PrevUses;
Comment on lines +195 to +196
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These sets aren't used outside of the lambda. Just make the lambda a helper function with these used locally?

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These sets are used to record the defs and uses of phis that have already been checked in the current MBB.
They need to be initialized and retain register information across multiple calls to the lambda.
Therefore, wouldn't it be better to place these sets outside the lambda?

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ok

auto IsLoopCarried = [&](MachineInstr &Phi) {
// Two cases are checked here: (1)The virtual register defined by the
// preceding phi is used by the succeeding phi;(2)The preceding phi uses the
// virtual register defined by the succeeding phi.
if (PrevUses.count(Phi.getOperand(0).getReg()))
return true;
PrevDefs.insert(Phi.getOperand(0).getReg());
for (unsigned I = 1, E = Phi.getNumOperands(); I != E; I += 2) {
if (PrevDefs.count(Phi.getOperand(I).getReg()))
return true;
PrevUses.insert(Phi.getOperand(I).getReg());
}
return false;
};
auto PLI = TII->analyzeLoopForPipelining(MBB);
for (auto &MI : *MBB) {
if (MI.isMetaInstruction() || MI.isTerminator())
continue;
if (MI.isPHI()) {
for (auto Def : PhiDefs)
if (MI.readsRegister(Def, TRI)) {
LLVM_DEBUG(
dbgs()
<< "Consecutive phis are not allowed in window scheduling!\n");
return false;
}
for (auto Def : MI.defs())
if (Def.isReg())
PhiDefs.push_back(Def.getReg());
if (IsLoopCarried(MI)) {
LLVM_DEBUG(dbgs() << "Loop carried phis are not supported yet!\n");
return false;
}
++SchedPhiNum;
++BestOffset;
} else
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3 changes: 2 additions & 1 deletion llvm/test/CodeGen/Hexagon/swp-ws-dead-def.mir
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@@ -1,6 +1,7 @@
# REQUIRES: asserts
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -o - 2>&1 | FileCheck %s
# RUN: -window-sched=force -filetype=null -verify-machineinstrs 2>&1 \
# RUN: | FileCheck %s

# CHECK: Best window offset is {{[0-9]+}} and Best II is {{[0-9]+}}.
# CHECK-LABEL: name: exp_approx_top_six
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7 changes: 4 additions & 3 deletions llvm/test/CodeGen/Hexagon/swp-ws-exp-dbg.mir
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@@ -1,11 +1,12 @@
# REQUIRES: asserts
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -o - 2>&1 | FileCheck %s
#
# RUN: -window-sched=force -filetype=null -verify-machineinstrs 2>&1 \
# RUN: | FileCheck %s

# The Window Scheduling algorithm will discard the debug IR, just like the SMS
# algorithm does. Additionally, the MMO information in the IR is also preserved
# to ensure that no barrier dependencies are generated within the loop body.
#

# CHECK: Best window offset is {{[0-9]+}} and Best II is {{[0-9]+}}.
# CHECK-LABEL: name: exp_approx
# CHECK: bb.5.for.body:
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3 changes: 2 additions & 1 deletion llvm/test/CodeGen/Hexagon/swp-ws-exp.mir
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@@ -1,6 +1,7 @@
# REQUIRES: asserts
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -o - 2>&1 | FileCheck %s
# RUN: -window-sched=force -filetype=null -verify-machineinstrs 2>&1 \
# RUN: | FileCheck %s

# CHECK: Best window offset is {{[0-9]+}} and Best II is {{[0-9]+}}.

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9 changes: 5 additions & 4 deletions llvm/test/CodeGen/Hexagon/swp-ws-fail-0.mir
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@@ -1,13 +1,14 @@
# REQUIRES: asserts
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -o - 2>&1 | FileCheck %s \
# RUN: -window-sched=force -filetype=null -verify-machineinstrs 2>&1 \
# RUN: | FileCheck %s \
# RUN: --check-prefix=CHECK-INITIALIZE
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -window-region-limit=1 -window-ii-limit=1 -o - \
# RUN: 2>&1 | FileCheck %s --check-prefix=CHECK-ANALYSE-II
# RUN: -window-sched=force -window-region-limit=1 -window-ii-limit=1 \
# RUN: -filetype=null 2>&1 | FileCheck %s --check-prefix=CHECK-ANALYSE-II
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -window-region-limit=1 -window-search-ratio=80 \
# RUN: -o - 2>&1 | FileCheck %s --check-prefix=CHECK-SCHED-NOT-NEEDED
# RUN: -filetype=null 2>&1 | FileCheck %s --check-prefix=CHECK-SCHED-NOT-NEEDED

# CHECK-INITIALIZE: There are too few MIs in the window region!
# CHECK-INITIALIZE: The WindowScheduler failed to initialize!
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14 changes: 9 additions & 5 deletions llvm/test/CodeGen/Hexagon/swp-ws-fail-1.mir
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@@ -1,10 +1,14 @@
# REQUIRES: asserts
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -o - 2>&1 | FileCheck %s \
# RUN: --check-prefix=CHECK-SUCCESSIVE-PHI

# CHECK-SUCCESSIVE-PHI: Consecutive phis are not allowed in window scheduling!
# CHECK-SUCCESSIVE-PHI: The WindowScheduler failed to initialize!
# RUN: -window-sched=force -filetype=null -verify-machineinstrs 2>&1 \
# RUN: | FileCheck %s

# CHECK: Loop carried phis are not supported yet!
# CHECK: The WindowScheduler failed to initialize!
# CHECK-LABEL: body: |
# CHECK: bb.3 (machine-block-address-taken):
# CHECK: [[REG:%[0-9]+]]:intregs = PHI {{%[0-9]+}}, %bb.1, {{%[0-9]+}}, %bb.3
# CHECK: {{%[0-9]+}}:intregs = PHI {{%[0-9]+}}, %bb.1, [[REG]], %bb.3

---
name: relu
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3 changes: 2 additions & 1 deletion llvm/test/CodeGen/Hexagon/swp-ws-fail-2.mir
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@@ -1,6 +1,7 @@
# REQUIRES: asserts
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -o - 2>&1 | FileCheck %s
# RUN: -window-sched=force -filetype=null -verify-machineinstrs 2>&1 \
# RUN: | FileCheck %s

# CHECK: The WindowScheduler failed to initialize!

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52 changes: 52 additions & 0 deletions llvm/test/CodeGen/Hexagon/swp-ws-fail-3.mir
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@@ -0,0 +1,52 @@
# REQUIRES: asserts
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -filetype=null -verify-machineinstrs 2>&1 \
# RUN: | FileCheck %s

# CHECK: Loop carried phis are not supported yet!
# CHECK: The WindowScheduler failed to initialize!
# CHECK-LABEL: body: |
# CHECK: bb.3 (machine-block-address-taken):
# CHECK: {{%[0-9]+}}:intregs = PHI {{%[0-9]+}}, %bb.1, [[REG:%[0-9]+]], %bb.3
# CHECK: [[REG]]:intregs = PHI {{%[0-9]+}}, %bb.1, {{%[0-9]+}}, %bb.3

---
name: relu
tracksRegLiveness: true
body: |
bb.0:
successors: %bb.2(0x30000000), %bb.1(0x50000000)
liveins: $r0, $r1, $r2

%0:intregs = COPY $r2
%1:intregs = COPY $r1
%2:intregs = COPY $r0
%3:predregs = C2_cmpeqi %2, 0
J2_jumpt killed %3, %bb.2, implicit-def dead $pc
J2_jump %bb.1, implicit-def dead $pc

bb.1:
successors: %bb.3(0x80000000)

%4:hvxvr = V6_vd0
%5:intregs = A2_addi %2, 31
%6:intregs = S2_lsr_i_r %5, 5
%7:intregs = COPY %6
J2_loop0r %bb.3, %7, implicit-def $lc0, implicit-def $sa0, implicit-def $usr
J2_jump %bb.3, implicit-def dead $pc

bb.2:
PS_jmpret $r31, implicit-def dead $pc

bb.3 (machine-block-address-taken):
successors: %bb.3(0x7c000000), %bb.2(0x04000000)

%8:intregs = PHI %0, %bb.1, %9, %bb.3
%9:intregs = PHI %1, %bb.1, %10, %bb.3
%11:hvxvr, %10:intregs = V6_vL32b_pi %9, 128
%12:hvxvr = V6_vmaxw killed %11, %4
%13:intregs = V6_vS32b_pi %8, 128, killed %12
ENDLOOP0 %bb.3, implicit-def $pc, implicit-def $lc0, implicit $sa0, implicit $lc0
J2_jump %bb.2, implicit-def dead $pc

...
3 changes: 2 additions & 1 deletion llvm/test/CodeGen/Hexagon/swp-ws-meta-instr.mir
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@@ -1,6 +1,7 @@
# REQUIRES: asserts
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -o - 2>&1 | FileCheck %s
# RUN: -window-sched=force -filetype=null -verify-machineinstrs 2>&1 \
# RUN: | FileCheck %s

# CHECK-NOT: PSEUDO_PROBE
# CHECK: Best window offset is {{[0-9]+}} and Best II is {{[0-9]+}}.
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3 changes: 2 additions & 1 deletion llvm/test/CodeGen/Hexagon/swp-ws-phi.mir
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@@ -1,6 +1,7 @@
# REQUIRES: asserts
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -filetype=null 2>&1 | FileCheck %s
# RUN: -window-sched=force -filetype=null -verify-machineinstrs 2>&1 \
# RUN: | FileCheck %s

# CHECK: Window scheduling is not needed!
# CHECK-LABEL: body: |
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3 changes: 2 additions & 1 deletion llvm/test/CodeGen/Hexagon/swp-ws-sqrt.mir
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@@ -1,6 +1,7 @@
# REQUIRES: asserts
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -o - 2>&1 | FileCheck %s
# RUN: -window-sched=force -filetype=null -verify-machineinstrs 2>&1 \
# RUN: | FileCheck %s

# CHECK: Best window offset is {{[0-9]+}} and Best II is {{[0-9]+}}.

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3 changes: 2 additions & 1 deletion llvm/test/CodeGen/Hexagon/swp-ws-weak-dep.mir
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@@ -1,6 +1,7 @@
# REQUIRES: asserts
# RUN: llc --march=hexagon %s -run-pass=pipeliner -debug-only=pipeliner \
# RUN: -window-sched=force -filetype=null 2>&1 | FileCheck %s
# RUN: -window-sched=force -filetype=null -verify-machineinstrs 2>&1 \
# RUN: | FileCheck %s

# CHECK: SU(3): Ord Latency=0 Weak
# CHECK: SU(1): Ord Latency=0 Weak
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