[PATCH] D108221: [LoopIdiom] Keep TBAA when creating memcpy/memmove

[William Moses via Phabricator via llvm-commits]

wsmoses created this revision.
wsmoses added reviewers: jdoerfert, lebedev.ri, eopXD, Whitney.
Herald added subscribers: jeroen.dobbelaere, kosarev, hiraditya.
wsmoses requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

When upgrading a loop of load/store to a memcpy, the existing pass does not keep existing aliasing information. This patch allows existing aliasing information to be kept.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D108221

Files:
  llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
  llvm/test/Transforms/LoopIdiom/memcpy-tbaa.ll


Index: llvm/test/Transforms/LoopIdiom/memcpy-tbaa.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/LoopIdiom/memcpy-tbaa.ll
@@ -0,0 +1,42 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -loop-idiom < %s -S | FileCheck %s
+
+define void @looper(double* noalias nocapture readonly %M, double* noalias nocapture %out) {
+; CHECK-LABEL: @looper(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[OUT1:%.*]] = bitcast double* [[OUT:%.*]] to i8*
+; CHECK-NEXT:    [[M2:%.*]] = bitcast double* [[M:%.*]] to i8*
+; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 [[OUT1]], i8* align 8 [[M2]], i64 256, i1 false), !tbaa [[TBAA0:![0-9]+]]
+; CHECK-NEXT:    br label [[FOR_BODY4:%.*]]
+; CHECK:       for.body4:
+; CHECK-NEXT:    [[J_020:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[FOR_BODY4]] ]
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds double, double* [[M]], i64 [[J_020]]
+; CHECK-NEXT:    [[A0:%.*]] = load double, double* [[ARRAYIDX]], align 8, !tbaa [[TBAA0]]
+; CHECK-NEXT:    [[ARRAYIDX8:%.*]] = getelementptr inbounds double, double* [[OUT]], i64 [[J_020]]
+; CHECK-NEXT:    [[INC]] = add nuw nsw i64 [[J_020]], 1
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp ult i64 [[J_020]], 31
+; CHECK-NEXT:    br i1 [[CMP2]], label [[FOR_BODY4]], label [[FOR_COND_CLEANUP:%.*]]
+; CHECK:       for.cond.cleanup:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body4
+
+for.body4:                                        ; preds = %for.cond1.preheader, %for.body4
+  %j.020 = phi i64 [ 0, %entry ], [ %inc, %for.body4 ]
+  %arrayidx = getelementptr inbounds double, double* %M, i64 %j.020
+  %a0 = load double, double* %arrayidx, align 8, !tbaa !5
+  %arrayidx8 = getelementptr inbounds double, double* %out, i64 %j.020
+  store double %a0, double* %arrayidx8, align 8, !tbaa !5
+  %inc = add nuw nsw i64 %j.020, 1
+  %cmp2 = icmp ult i64 %j.020, 31
+  br i1 %cmp2, label %for.body4, label %for.cond.cleanup
+
+for.cond.cleanup:                                 ; preds = %for.cond.cleanup3
+  ret void
+}
+
+!5 = !{!6, !6, i64 0}
+!6 = !{!"double", !7, i64 0}
+!7 = !{!"omnipotent char", !8, i64 0}
+!8 = !{!"Simple C++ TBAA"}
Index: llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -1382,17 +1382,24 @@
   Value *NumBytes =
       Expander.expandCodeFor(NumBytesS, IntIdxTy, Preheader->getTerminator());
 
+  AAMDNodes AATags;
+  TheLoad->getAAMetadata(AATags);
+  TheStore->getAAMetadata(AATags, /*Merge*/ true);
+
   CallInst *NewCall = nullptr;
   // Check whether to generate an unordered atomic memcpy:
   //  If the load or store are atomic, then they must necessarily be unordered
   //  by previous checks.
   if (!TheStore->isAtomic() && !TheLoad->isAtomic()) {
     if (UseMemMove)
-      NewCall = Builder.CreateMemMove(StoreBasePtr, StoreAlign, LoadBasePtr,
-                                      LoadAlign, NumBytes);
+      NewCall = Builder.CreateMemMove(
+          StoreBasePtr, StoreAlign, LoadBasePtr, LoadAlign, NumBytes,
+          /*isVolatile*/ false, AATags.TBAA, AATags.Scope, AATags.NoAlias);
     else
-      NewCall = Builder.CreateMemCpy(StoreBasePtr, StoreAlign, LoadBasePtr,
-                                     LoadAlign, NumBytes);
+      NewCall =
+          Builder.CreateMemCpy(StoreBasePtr, StoreAlign, LoadBasePtr, LoadAlign,
+                               NumBytes, /*isVolatile*/ false, AATags.TBAA,
+                               AATags.TBAAStruct, AATags.Scope, AATags.NoAlias);
   } else {
     // For now don't support unordered atomic memmove.
     if (UseMemMove)
@@ -1416,7 +1423,8 @@
     // have an alignment but non-atomic loads/stores may not.
     NewCall = Builder.CreateElementUnorderedAtomicMemCpy(
         StoreBasePtr, StoreAlign.getValue(), LoadBasePtr, LoadAlign.getValue(),
-        NumBytes, StoreSize);
+        NumBytes, StoreSize, AATags.TBAA, AATags.TBAAStruct, AATags.Scope,
+        AATags.NoAlias);
   }
   NewCall->setDebugLoc(TheStore->getDebugLoc());
 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D108221.366948.patch
Type: text/x-patch
Size: 4235 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20210817/cf4711ce/attachment.bin>