[X86] Fix Update Kill Register in Avoid SFB Pass - Bug 37153

[lsaba]

Summary

Reset the Kill flag to false for the newly created small load/store instructions, except for the last created load/store which should have the original kill flag status.

[lsaba]

ping

[craig.topper]

lib/Target/X86/X86AvoidStoreForwardingBlocks.cpp

429

Use X86::AddrNumOperands instead of 5?

[lsaba]

fix @craig.topper comment

[craig.topper]

I thought I wrote this comment when I reviewed yesterday, but I guess it didnt' get saved somehow.

lib/Target/X86/X86AvoidStoreForwardingBlocks.cpp

406–409

Can you do

MachineInstr *NewLoad = BuildMI....

Then you don't need to use getPrevNode. same with the store below.

[lsaba]

done @craig.topper

[craig.topper]

LGTM

lib/Target/X86/X86AvoidStoreForwardingBlocks.cpp

void X86AvoidSFBPass::buildCopy(MachineInstr *LoadInst, unsigned NLoadOpcode,
   BuildMI(*MBB, LoadInst, LoadInst->getDebugLoc(), TII->get(NLoadOpcode), Reg1)
       .add(LoadBase)
       .addImm(1)
       .addReg(X86::NoRegister)
       .addImm(LoadDisp)
       .addReg(X86::NoRegister)
       .addMemOperand(
           MBB->getParent()->getMachineMemOperand(LMMO, LMMOffset, Size));
-  DEBUG(LoadInst->getPrevNode()->dump());
+  MachineInstr *NewLoad = LoadInst->getPrevNode();
+  if (LoadBase.isReg())
+    getBaseOperand(NewLoad).setIsKill(false);
+  DEBUG(NewLoad->dump());
   // If the load and store are consecutive, use the loadInst location to
   // reduce register pressure.
   MachineInstr *StInst = StoreInst;
   if (StoreInst->getPrevNode() == LoadInst)
     StInst = LoadInst;
   BuildMI(*MBB, StInst, StInst->getDebugLoc(), TII->get(NStoreOpcode))
       .add(StoreBase)
       .addImm(1)
       .addReg(X86::NoRegister)
       .addImm(StoreDisp)
       .addReg(X86::NoRegister)
       .addReg(Reg1)
       .addMemOperand(
           MBB->getParent()->getMachineMemOperand(SMMO, SMMOffset, Size));
-  DEBUG(StInst->getPrevNode()->dump());
+  MachineInstr *NewStore = StInst->getPrevNode();
+  if (StoreBase.isReg())
+    getBaseOperand(NewStore).setIsKill(false);
+  MachineOperand &StoreSrcVReg = StoreInst->getOperand(5);
+  assert(StoreSrcVReg.isReg() && "Expected virtual register");
+  NewStore->getOperand(5).setIsKill(StoreSrcVReg.isKill());
+  DEBUG(NewStore->dump());
 }
 
 void X86AvoidSFBPass::buildCopies(int Size, MachineInstr *LoadInst,
                                   int64_t LdDispImm, MachineInstr *StoreInst,
                                   int64_t StDispImm, int64_t LMMOffset,
                                   int64_t SMMOffset) {
   int LdDisp = LdDispImm;
   int StDisp = StDispImm;

test/CodeGen/X86/avoid-sfb-kill-flags.mir

+# RUN: llc -o - %s -mtriple=x86_64-- -run-pass=x86-avoid-SFB | FileCheck %s
+--- |
+  ; ModuleID = '../test/CodeGen/X86/avoid-sfb-mir.ll'
+  source_filename = "../test/CodeGen/X86/avoid-sfb-mir.ll"
+  target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+  target triple = "x86_64-unknown-linux-gnu"
+
+  %struct.S = type { i32, i32, i32, i32 }
+
+  ; Function Attrs: nounwind uwtable
+  define void @test_imm_store(%struct.S* noalias nocapture %s1, %struct.S* nocapture %s2, i32 %x, %struct.S* nocapture %s3) local_unnamed_addr #0 {
+  entry:
+    %a2 = bitcast %struct.S* %s1 to i32*
+    store i32 0, i32* %a2, align 4
+    %a13 = bitcast %struct.S* %s3 to i32*
+    store i32 1, i32* %a13, align 4
+    %0 = bitcast %struct.S* %s2 to i8*
+    %1 = bitcast %struct.S* %s1 to i8*
+    call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 %0, i8* align 4 %1, i64 16, i1 false)
+    ret void
+  }
+
+  declare void @bar(%struct.S*) local_unnamed_addr
+
+  ; Function Attrs: argmemonly nounwind
+  declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly, i8* nocapture readonly, i64, i1) #1
+
+...
+---
+name:            test_imm_store
+alignment:       4
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: gr64 }
+  - { id: 1, class: gr64 }
+  - { id: 2, class: gr32 }
+  - { id: 3, class: gr64 }
+  - { id: 4, class: vr128 }
+liveins:
+  - { reg: '$rdi', virtual-reg: '%0' }
+  - { reg: '$rsi', virtual-reg: '%1' }
+  - { reg: '$rcx', virtual-reg: '%3' }
+body:             |
+  bb.0.entry:
+    liveins: $rdi, $rsi, $rcx
+    ; CHECK: MOV32mi %0, 1, $noreg, 0, $noreg, 0 :: (store 4 into %ir.a2)
+    ; CHECK-NEXT: MOV32mi %3, 1, $noreg, 0, $noreg, 1 :: (store 4 into %ir.a13)
+    ; CHECK-NEXT: %5:gr32 = MOV32rm %0, 1, $noreg, 0, $noreg :: (load 4 from %ir.1)
+    ; CHECK-NEXT: MOV32mr %1, 1, $noreg, 0, $noreg, killed %5 :: (store 4 into %ir.0)
+    ; CHECK-NEXT: %6:gr64 = MOV64rm %0, 1, $noreg, 4, $noreg :: (load 8 from %ir.1 + 4, align 4)
+    ; CHECK-NEXT: MOV64mr %1, 1, $noreg, 4, $noreg, killed %6 :: (store 8 into %ir.0 + 4, align 4)
+    ; CHECK-NEXT: %7:gr32 = MOV32rm killed %0, 1, $noreg, 12, $noreg :: (load 4 from %ir.1 + 12)
+    ; CHECK-NEXT: MOV32mr killed %1, 1, $noreg, 12, $noreg, killed %7 :: (store 4 into %ir.0 + 12)
+
+    %3:gr64 = COPY $rcx
+    %1:gr64 = COPY $rsi
+    %0:gr64 = COPY $rdi
+    MOV32mi %0, 1, $noreg, 0, $noreg, 0 :: (store 4 into %ir.a2)
+    MOV32mi %3, 1, $noreg, 0, $noreg, 1 :: (store 4 into %ir.a13)
+    %4:vr128 = MOVUPSrm killed %0, 1, $noreg, 0, $noreg :: (load 16 from %ir.1, align 4)
+    MOVUPSmr killed %1, 1, $noreg, 0, $noreg, killed %4 :: (store 16 into %ir.0, align 4)
+    RET 0
+
+...

test/CodeGen/X86/avoid-sfb-overlaps.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc < %s -mtriple=x86_64-linux | FileCheck %s -check-prefix=CHECK
-; RUN: llc < %s -mtriple=x86_64-linux --x86-disable-avoid-SFB | FileCheck %s --check-prefix=DISABLED
-; RUN: llc < %s -mtriple=x86_64-linux -mcpu=core-avx2 | FileCheck %s -check-prefix=CHECK-AVX2
-; RUN: llc < %s -mtriple=x86_64-linux -mcpu=skx | FileCheck %s -check-prefix=CHECK-AVX512
+; RUN: llc < %s -mtriple=x86_64-linux -verify-machineinstrs | FileCheck %s -check-prefix=CHECK
+; RUN: llc < %s -mtriple=x86_64-linux --x86-disable-avoid-SFB -verify-machineinstrs | FileCheck %s --check-prefix=DISABLED
+; RUN: llc < %s -mtriple=x86_64-linux -mcpu=core-avx2 -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-AVX2
+; RUN: llc < %s -mtriple=x86_64-linux -mcpu=skx -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-AVX512
 
 ; ModuleID = '../testSFB/testOverlapBlocks.c'
 source_filename = "../testSFB/testOverlapBlocks.c"
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 ; Function Attrs: nounwind uwtable
 define dso_local void @test_overlap_1(i8* nocapture %A, i32 %x) local_unnamed_addr #0 {

test/CodeGen/X86/avoid-sfb.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc < %s -mtriple=x86_64-linux | FileCheck %s -check-prefix=CHECK
-; RUN: llc < %s -mtriple=x86_64-linux --x86-disable-avoid-SFB | FileCheck %s --check-prefix=DISABLED
-; RUN: llc < %s -mtriple=x86_64-linux -mcpu=core-avx2 | FileCheck %s -check-prefix=CHECK-AVX2
-; RUN: llc < %s -mtriple=x86_64-linux -mcpu=skx | FileCheck %s -check-prefix=CHECK-AVX512
+; RUN: llc < %s -mtriple=x86_64-linux -verify-machineinstrs | FileCheck %s -check-prefix=CHECK
+; RUN: llc < %s -mtriple=x86_64-linux --x86-disable-avoid-SFB -verify-machineinstrs | FileCheck %s --check-prefix=DISABLED
+; RUN: llc < %s -mtriple=x86_64-linux -mcpu=core-avx2 -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-AVX2
+; RUN: llc < %s -mtriple=x86_64-linux -mcpu=skx -verify-machineinstrs | FileCheck %s -check-prefix=CHECK-AVX512
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 %struct.S = type { i32, i32, i32, i32 }
 
 ; Function Attrs: nounwind uwtable
 define void @test_conditional_block(%struct.S* nocapture noalias %s1 , %struct.S* nocapture noalias %s2, i32 %x, %struct.S* nocapture noalias  %s3, %struct.S* nocapture noalias readonly %s4) local_unnamed_addr #0 {