[PATCH] D112321: [DSE] Support redundant stores eliminated by memset.
Florian Hahn via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Oct 22 09:04:40 PDT 2021
fhahn created this revision.
fhahn added reviewers: nikic, asbirlea, george.burgess.iv, yurai007.
Herald added subscribers: pengfei, hiraditya.
fhahn requested review of this revision.
Herald added a project: LLVM.
This patch adds support to remove stores that write the same value
as earlier memesets.
It uses isOverwrite to check that a memset completely overwrites a later
store. The candidate store must store the same bytewise value as the
byte stored by the memset.
Improvements of dse.NumRedundantStores on MultiSource/CINT2006/CPF2006
on X86 with -O3:
test-suite...oxyApps-C++/miniFE/miniFE.test 1.00 5.00 400.0%
test-suite...marks/7zip/7zip-benchmark.test 2.00 8.00 300.0%
test-suite...lications/sqlite3/sqlite3.test 2.00 7.00 250.0%
test-suite...lications/ClamAV/clamscan.test 1.00 2.00 100.0%
test-suite.../CINT2006/403.gcc/403.gcc.test 7.00 11.00 57.1%
test-suite...006/447.dealII/447.dealII.test 33.00 51.00 54.5%
test-suite...0.perlbench/400.perlbench.test 2.00 3.00 50.0%
test-suite.../Benchmarks/Bullet/bullet.test 12.00 16.00 33.3%
test-suite.../Applications/lemon/lemon.test 5.00 6.00 20.0%
test-suite...DOE-ProxyApps-C/CoMD/CoMD.test 6.00 7.00 16.7%
test-suite...pplications/oggenc/oggenc.test 7.00 8.00 14.3%
test-suite...3.xalancbmk/483.xalancbmk.test 62.00 67.00 8.1%
test-suite...T2006/458.sjeng/458.sjeng.test NaN 1.00 nan%
test-suite...CFP2006/444.namd/444.namd.test NaN 1.00 nan%
test-suite...nsumer-jpeg/consumer-jpeg.test NaN 3.00 nan%
test-suite...rks/tramp3d-v4/tramp3d-v4.test NaN 13.00 nan%
test-suite...oxyApps-C/miniGMG/miniGMG.test NaN 25.00 nan%
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D112321
Files:
llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
llvm/test/Transforms/DeadStoreElimination/stores-of-existing-values.ll
Index: llvm/test/Transforms/DeadStoreElimination/stores-of-existing-values.ll
===================================================================
--- llvm/test/Transforms/DeadStoreElimination/stores-of-existing-values.ll
+++ llvm/test/Transforms/DeadStoreElimination/stores-of-existing-values.ll
@@ -402,8 +402,6 @@
define void @test12_memset_simple(i8* %ptr) {
; CHECK-LABEL: @test12_memset_simple(
; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* [[PTR:%.*]], i8 0, i64 10, i1 false)
-; CHECK-NEXT: [[PTR_5:%.*]] = getelementptr i8, i8* [[PTR]], i64 4
-; CHECK-NEXT: store i8 0, i8* [[PTR_5]], align 1
; CHECK-NEXT: ret void
;
call void @llvm.memset.p0i8.i64(i8* %ptr, i8 0, i64 10, i1 false)
@@ -417,8 +415,6 @@
; CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* [[PTR:%.*]], i8 0, i64 10, i1 false)
; CHECK-NEXT: [[PTR_4:%.*]] = getelementptr i8, i8* [[PTR]], i64 4
; CHECK-NEXT: store i8 8, i8* [[PTR_4]], align 1
-; CHECK-NEXT: [[PTR_5:%.*]] = getelementptr i8, i8* [[PTR]], i64 5
-; CHECK-NEXT: store i8 0, i8* [[PTR_5]], align 1
; CHECK-NEXT: ret void
;
call void @llvm.memset.p0i8.i64(i8* %ptr, i8 0, i64 10, i1 false)
Index: llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -1990,10 +1990,32 @@
UpperDef = dyn_cast<MemoryDef>(Def->getDefiningAccess());
if (!UpperDef || MSSA.isLiveOnEntryDef(UpperDef))
continue;
- auto *DefInst = Def->getMemoryInst();
- auto *UpperInst = UpperDef->getMemoryInst();
+
+ Instruction *DefInst = Def->getMemoryInst();
+ Instruction *UpperInst = UpperDef->getMemoryInst();
+ auto IsRedundantStore = [this, DefInst,
+ UpperInst](MemoryLocation UpperLoc) {
+ if (DefInst->isIdenticalTo(UpperInst))
+ return true;
+ if (auto *MemSetI = dyn_cast<MemSetInst>(UpperInst)) {
+ if (auto *SI = dyn_cast<StoreInst>(DefInst)) {
+ auto MaybeDefLoc = getLocForWriteEx(DefInst);
+ if (!MaybeDefLoc)
+ return false;
+ int64_t InstWriteOffset = 0;
+ int64_t DepWriteOffset = 0;
+ auto OR = isOverwrite(UpperInst, DefInst, UpperLoc, *MaybeDefLoc,
+ InstWriteOffset, DepWriteOffset);
+ Value *StoredByte = isBytewiseValue(SI->getValueOperand(), DL);
+ return StoredByte && StoredByte == MemSetI->getOperand(1) &&
+ OR == OW_Complete;
+ }
+ }
+ return false;
+ };
+
auto MaybeUpperLoc = getLocForWriteEx(UpperInst);
- if (!MaybeUpperLoc || !DefInst->isIdenticalTo(UpperInst) ||
+ if (!MaybeUpperLoc || !IsRedundantStore(*MaybeUpperLoc) ||
isReadClobber(*MaybeUpperLoc, DefInst))
continue;
deleteDeadInstruction(DefInst);
@@ -2163,11 +2185,11 @@
}
}
- MadeChange |= State.eliminateRedundantStoresOfExistingValues();
if (EnablePartialOverwriteTracking)
for (auto &KV : State.IOLs)
MadeChange |= removePartiallyOverlappedStores(State.DL, KV.second, TLI);
+ MadeChange |= State.eliminateRedundantStoresOfExistingValues();
MadeChange |= State.eliminateDeadWritesAtEndOfFunction();
return MadeChange;
}
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D112321.381569.patch
Type: text/x-patch
Size: 3411 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20211022/c0262cad/attachment.bin>
More information about the llvm-commits
mailing list