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[Hexagon] Add Hexagon Copy Hoisting pass #89313

Merged

iajbar merged 5 commits into llvm:main from quic-pmacmurr:main

Apr 27, 2024

Contributor

quic-pmacmurr commented Apr 18, 2024

Adds the HexagonCopyHoisting pass, which moves a common copy instruction into a basic block if it is present in all successor basic blocks.


          [Hexagon] Add Hexagon Copy Hoisting pass

cb47218

The purpose of this pass is to move the common copy instructions that
are present in all the successor of a basic block (BB) to the end of BB.

Co-authored-by: Jyotsna Verma <jverma@quicinc.com>

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iajbar requested review from iajbar and SundeepKushwaha

April 18, 2024 21:17

github-actions bot commented Apr 19, 2024 •

edited

✅ With the latest revision this PR passed the C/C++ code formatter.

quic-pmacmurr added 2 commits

April 19, 2024 08:41


          Apply clang-format

d287ada


          Fix clang-format

c7db6f1

I was running an outdated version

kparzysz reviewed

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Contributor

kparzysz left a comment

The comments are primarily about modernizing this code. Please use range-for loops wherever possible.

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

+              public:
+                static char ID;
+                HexagonCopyHoisting() : MachineFunctionPass(ID), MFN(0), MRI(0) {

Contributor

kparzysz Apr 19, 2024

Use nullptr instead of 0.

Contributor Author

quic-pmacmurr Apr 19, 2024

Done

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

+                // Traverse through the basic blocks again and move the COPY instructions
+                // that are present in all the successors of BB to BB.
+                bool changed = false;

Contributor

kparzysz Apr 19, 2024

Throughout this file variable names start with a capital letter. Please keep it consistent.

Contributor Author

quic-pmacmurr Apr 19, 2024

Fixed

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

+                // Traverse through the basic blocks again and move the COPY instructions
+                // that are present in all the successors of BB to BB.
+                bool changed = false;
+                for (auto I = po_begin(&Fn), E = po_end(&Fn); I != E; ++I) {

Contributor

kparzysz Apr 19, 2024

Prefer to use range-for loops over iterator based loops. Most things in LLVM that have begin/end iterators also have an iterator range that you can use in a range-for loop.

Here specifically that would be for (MachineBasicBlock *BB : post_order(&Fn)), then you'd need to use BB-> instead of BB. in the body.

Contributor Author

quic-pmacmurr Apr 19, 2024

Fixed

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

+                MachineFunction *MFN;
+                MachineRegisterInfo *MRI;
+                StringMap<MachineInstr *> CopyMI;
+                std::vector<StringMap<MachineInstr *>> CopyMIList;

Contributor

kparzysz Apr 19, 2024

It would be more efficient to use a DenseMap with the key being a pair of registers:

DenseMap<std::pair<Register, Register>, MachineInstr *>

but it's up to you.

Contributor Author

quic-pmacmurr Apr 19, 2024

I agree; done

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

Comment on lines 127 to 128

		for (auto BI = MFN->begin(), BE = MFN->end(); BI != BE; ++BI) {
		MachineBasicBlock BB = &BI;

Contributor

kparzysz Apr 19, 2024

Range-for:

for (MachineBasicBlock &BB : *MFN)

Contributor Author

quic-pmacmurr Apr 19, 2024

Fixed

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

Comment on lines 254 to 257

+                  MachineInstr *otherMI = &*MII;
+                  for (MachineInstr::mop_iterator Mo = otherMI->operands_begin(),
+                                                  E = otherMI->operands_end();
+                       Mo != E; ++Mo)

Contributor

kparzysz Apr 19, 2024

Same as above.

Contributor Author

quic-pmacmurr Apr 19, 2024

Fixed

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

+              }
+              void HexagonCopyHoisting::moveCopyInstr(MachineBasicBlock *DestBB,
+                                                      StringRef key, MachineInstr *MI) {

Contributor

kparzysz Apr 19, 2024

Key

Contributor Author

quic-pmacmurr Apr 19, 2024

Fixed

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

+                addMItoCopyList(MI);
+                auto I = ++(DestBB->succ_begin()), E = DestBB->succ_end();
+                for (; I != E; ++I) {

Contributor

kparzysz Apr 19, 2024

for (auto I = std::next(DestBB->succ_begin()), E = DestBB->end(); ++I)

Contributor Author

quic-pmacmurr Apr 19, 2024

Fixed

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

Comment on lines 146 to 147

		unsigned DstReg = MI->getOperand(0).getReg();
		unsigned SrcReg = MI->getOperand(1).getReg();

Contributor

kparzysz Apr 19, 2024

MachineOperand::getReg() now returns Register, not unsigned. Please see llvm/include/llvm/CodeGen/Register.h.

Contributor Author

quic-pmacmurr Apr 19, 2024

Fixed

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

+                    MRI->getRegClass(SrcReg) != &Hexagon::IntRegsRegClass)
+                  return;
+                StringRef key;

Contributor

kparzysz Apr 19, 2024

Key

Contributor Author

quic-pmacmurr Apr 19, 2024

Fixed


          Code review changes

11039a7

kparzysz approved these changes

View reviewed changes

Contributor

kparzysz left a comment

LGTM with a few final comments.

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

Comment on lines 153 to 157

+                StringRef Key;
+                SmallString<256> TmpData("");
+                (void)Twine(Register::virtReg2Index(DstReg)).toStringRef(TmpData);
+                TmpData += '=';
+                Key = Twine(Register::virtReg2Index(SrcReg)).toStringRef(TmpData);

Contributor

kparzysz Apr 20, 2024

This is no longer needed.

Contributor Author

quic-pmacmurr Apr 22, 2024

Removed

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

+              #include "HexagonTargetMachine.h"
+              #include "llvm/ADT/PostOrderIterator.h"
+              #include "llvm/ADT/SmallString.h"
+              #include "llvm/ADT/StringMap.h"

Contributor

kparzysz Apr 20, 2024

I think this include can be removed (replaced with include of DenseMap.h). DenseMap.h seems to be included indirectly by some other header file, but it's a good idea to include it directly (in case something changes in that other header file).

Contributor Author

quic-pmacmurr Apr 22, 2024

Fixed

llvm/lib/Target/Hexagon/HexagonCopyHoisting.cpp Outdated

+                MachineFunction *MFN;
+                MachineRegisterInfo *MRI;
+                StringMap<MachineInstr *> CopyMI;

Contributor

kparzysz Apr 20, 2024

This seems unused now.

Contributor Author

quic-pmacmurr Apr 22, 2024

Removed

efriedma-quic requested a review from arsenm

April 21, 2024 00:05


          A few more code review changes

25de806

iajbar approved these changes

View reviewed changes

iajbar merged commit cb508a0 into llvm:main

3 checks passed

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Collaborator

mikaelholmen commented Apr 30, 2024

Hello @quic-pmacmurr @iajbar and others,

If you run the new testcase

 test/CodeGen/Hexagon/hexagon-copy-hoisting.mir

with verifiers on like:

llc -verify-machineinstrs -march=hexagon -run-pass hexagon-move-phicopy -o - test/CodeGen/Hexagon/hexagon-copy-hoisting.mir

then you get a whole bunch of complaints:

# After Hexagon Copy Hoisting
********** INTERVALS **********
R0 [0B,32r:0) 0@0B-phi
R1 [0B,16r:0)[144r,144d:2)[208r,208d:1) 0@0B-phi 1@208r 2@144r
%0 [32r,128B:0)[176B,192r:0) 0@32r  weight:0.000000e+00
%1 [16r,80r:0) 0@16r  weight:0.000000e+00
%2 [48r,64r:0) 0@48r  weight:0.000000e+00
%3 [64r,96r:0) 0@64r  weight:0.000000e+00
%4 [80r,144r:0)[176B,208r:0) 0@80r  weight:0.000000e+00
%5 [192r,192d:0) 0@192r  weight:0.000000e+00
RegMasks:
********** MACHINEINSTRS **********
# Machine code for function f0: NoPHIs, TracksLiveness
Frame Objects:
  fi#0: size=4, align=8, at location [SP]
Function Live Ins: $r0 in %0, $r1 in %1

0B	bb.0:
	; predecessors: %bb.1, %bb.2
	  successors: %bb.1(0x40000000), %bb.2(0x40000000); %bb.1(50.00%), %bb.2(50.00%)
	  liveins: $r0, $r1
16B	  %1:intregs = COPY $r1
32B	  %0:intregs = COPY $r0
48B	  %2:predregs = C2_cmpgt %0:intregs, %1:intregs
64B	  %3:predregs = C2_not %2:predregs
80B	  %4:intregs = COPY %1:intregs
96B	  J2_jumpt %3:predregs, %bb.2, implicit-def dead $pc
112B	  J2_jump %bb.1, implicit-def dead $pc

128B	bb.1:
	; predecessors: %bb.0
	  successors: %bb.0(0x80000000); %bb.0(100.00%)

144B	  $r1 = COPY %4:intregs
160B	  J2_jump %bb.0, implicit-def dead $pc

176B	bb.2:
	; predecessors: %bb.0
	  successors: %bb.0(0x80000000); %bb.0(100.00%)

192B	  dead %5:intregs = COPY %0:intregs
208B	  $r1 = COPY %4:intregs
224B	  J2_jump %bb.0, implicit-def dead $pc

# End machine code for function f0.

*** Bad machine code: Register not marked live out of predecessor ***
- function:    f0
- basic block: %bb.1  (0x56371f809550) [128B;176B)
- liverange:   [0B,32r:0) 0@0B-phi
- regunit:     R0
- ValNo:       0 (def 0B)
 live into %bb.0@0B, not live before 176B

*** Bad machine code: Register not marked live out of predecessor ***
- function:    f0
- basic block: %bb.2  (0x56371f809650) [176B;240B)
- liverange:   [0B,32r:0) 0@0B-phi
- regunit:     R0
- ValNo:       0 (def 0B)
 live into %bb.0@0B, not live before 240B

*** Bad machine code: Register not marked live out of predecessor ***
- function:    f0
- basic block: %bb.1  (0x56371f809550) [128B;176B)
- liverange:   [0B,16r:0)[144r,144d:2)[208r,208d:1) 0@0B-phi 1@208r 2@144r
- regunit:     R1
- ValNo:       0 (def 0B)
 live into %bb.0@0B, not live before 176B

*** Bad machine code: Register not marked live out of predecessor ***
- function:    f0
- basic block: %bb.2  (0x56371f809650) [176B;240B)
- liverange:   [0B,16r:0)[144r,144d:2)[208r,208d:1) 0@0B-phi 1@208r 2@144r
- regunit:     R1
- ValNo:       0 (def 0B)
 live into %bb.0@0B, not live before 240B
LLVM ERROR: Found 4 machine code errors.

(I noticed this when I ran lit tests after compiling with EXPENSIVE_CHECKS on. But as you see above you can reproduce just by adding -verify-machineinstrs to the llc command)

Contributor Author

quic-pmacmurr commented May 1, 2024

Hi @mikaelholmen, thank you for bringing this to my attention. I have fixed the test case in a new PR: #90740

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