maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[MachineCopyPropagation] Expose more dead copies across instructions with regmasks 

When encountering instructions with regmasks, instead of cleaning up all the
elements in MaybeDeadCopies map, remove only the instructions erased. By keeping
more instruction in MaybeDeadCopies, this change will expose more dead copies
across instructions with regmasks.

llvm-svn: 264462
This commit is contained in:
Jun Bum Lim 2016-03-25 21:15:35 +00:00
parent fa250cad37
commit 36c53fe147
2 changed files with 81 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
llvm/lib/CodeGen/MachineCopyPropagation.cpp
View File

@ -285,18 +285,28 @@ void MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
// defined registers.
if (RegMask) {
// Erase any MaybeDeadCopies whose destination register is clobbered.
for (MachineInstr *MaybeDead : MaybeDeadCopies) {
for (SmallSetVector<MachineInstr *, 8>::iterator DI =
MaybeDeadCopies.begin();
DI != MaybeDeadCopies.end();) {
MachineInstr *MaybeDead = *DI;
unsigned Reg = MaybeDead->getOperand(0).getReg();
assert(!MRI->isReserved(Reg));
if (!RegMask->clobbersPhysReg(Reg))
if (!RegMask->clobbersPhysReg(Reg)) {
++DI;
continue;
}
DEBUG(dbgs() << "MCP: Removing copy due to regmask clobbering: ";
MaybeDead->dump());
// erase() will return the next valid iterator pointing to the next
// element after the erased one.
DI = MaybeDeadCopies.erase(DI);
MaybeDead->eraseFromParent();
Changed = true;
++NumDeletes;
}
MaybeDeadCopies.clear();
removeClobberedRegsFromMap(AvailCopyMap, *RegMask);
removeClobberedRegsFromMap(CopyMap, *RegMask);
@ -348,3 +358,4 @@ bool MachineCopyPropagation::runOnMachineFunction(MachineFunction &MF) {
return Changed;
}

67
llvm/test/CodeGen/MIR/AArch64/machine-dead-copy.mir Normal file
View File

@ -0,0 +1,67 @@
# RUN: llc -mtriple=aarch64-none-linux-gnu -run-pass machine-cp -verify-machineinstrs -o /dev/null %s 2>&1 | FileCheck %s
--- |
define i32 @copyprop1(i32 %a, i32 %b) { ret i32 %a }
define i32 @copyprop2(i32 %a, i32 %b) { ret i32 %a }
define i32 @copyprop3(i32 %a, i32 %b) { ret i32 %a }
define i32 @copyprop4(i32 %a, i32 %b) { ret i32 %a }
declare i32 @foo(i32)
...
---
# The first copy is dead copy which is not used.
# CHECK-LABEL: name: copyprop1
# CHECK: bb.0:
# CHECK-NOT: %w20 = COPY
name: copyprop1
body: |
bb.0:
liveins: %w0, %w1
%w20 = COPY %w1
BL @foo, csr_aarch64_aapcs, implicit %w0, implicit-def %w0
RET_ReallyLR implicit %w0
...
---
# The first copy is not a dead copy which is used in the second copy after the
# call.
# CHECK-LABEL: name: copyprop2
# CHECK: bb.0:
# CHECK: %w20 = COPY
name: copyprop2
body: |
bb.0:
liveins: %w0, %w1
%w20 = COPY %w1
BL @foo, csr_aarch64_aapcs, implicit %w0, implicit-def %w0
%w0 = COPY %w20
RET_ReallyLR implicit %w0
...
---
# Both the first and second copy are dead copies which are not used.
# CHECK-LABEL: name: copyprop3
# CHECK: bb.0:
# CHECK-NOT: COPY
name: copyprop3
body: |
bb.0:
liveins: %w0, %w1
%w20 = COPY %w1
BL @foo, csr_aarch64_aapcs, implicit %w0, implicit-def %w0
%w20 = COPY %w0
RET_ReallyLR implicit %w0
...
# The second copy is removed as a NOP copy, after then the first copy become
# dead which should be removed as well.
# CHECK-LABEL: name: copyprop4
# CHECK: bb.0:
# CHECK-NOT: COPY
name: copyprop4
body: |
bb.0:
liveins: %w0, %w1
%w20 = COPY %w0
%w0 = COPY %w20
BL @foo, csr_aarch64_aapcs, implicit %w0, implicit-def %w0
RET_ReallyLR implicit %w0
...