Recommitting r275284: add support to inline __builtin_mempcpy
Patch by Sunita Marathe
Third try, now following fixes to MSan to handle mempcy in such a way that this commit won't break the MSan buildbots. (Thanks, Evegenii!)
llvm-svn: 277189
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 01c13fa..183cbcd 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -6043,6 +6043,49 @@
return false;
}
+///
+/// visitMemPCpyCall -- lower a mempcpy call as a memcpy followed by code to
+/// to adjust the dst pointer by the size of the copied memory.
+bool SelectionDAGBuilder::visitMemPCpyCall(const CallInst &I) {
+
+ // Verify argument count: void *mempcpy(void *, const void *, size_t)
+ if (I.getNumArgOperands() != 3)
+ return false;
+
+ SDValue Dst = getValue(I.getArgOperand(0));
+ SDValue Src = getValue(I.getArgOperand(1));
+ SDValue Size = getValue(I.getArgOperand(2));
+
+ unsigned DstAlign = DAG.InferPtrAlignment(Dst);
+ unsigned SrcAlign = DAG.InferPtrAlignment(Src);
+ unsigned Align = std::min(DstAlign, SrcAlign);
+ if (Align == 0) // Alignment of one or both could not be inferred.
+ Align = 1; // 0 and 1 both specify no alignment, but 0 is reserved.
+
+ bool isVol = false;
+ SDLoc sdl = getCurSDLoc();
+
+ // In the mempcpy context we need to pass in a false value for isTailCall
+ // because the return pointer needs to be adjusted by the size of
+ // the copied memory.
+ SDValue MC = DAG.getMemcpy(getRoot(), sdl, Dst, Src, Size, Align, isVol,
+ false, /*isTailCall=*/false,
+ MachinePointerInfo(I.getArgOperand(0)),
+ MachinePointerInfo(I.getArgOperand(1)));
+ assert(MC.getNode() != nullptr &&
+ "** memcpy should not be lowered as TailCall in mempcpy context **");
+ DAG.setRoot(MC);
+
+ // Check if Size needs to be truncated or extended.
+ Size = DAG.getSExtOrTrunc(Size, sdl, Dst.getValueType());
+
+ // Adjust return pointer to point just past the last dst byte.
+ SDValue DstPlusSize = DAG.getNode(ISD::ADD, sdl, Dst.getValueType(),
+ Dst, Size);
+ setValue(&I, DstPlusSize);
+ return true;
+}
+
/// visitStrCpyCall -- See if we can lower a strcpy or stpcpy call into an
/// optimized form. If so, return true and lower it, otherwise return false
/// and it will be lowered like a normal call.
@@ -6333,6 +6376,10 @@
if (visitMemCmpCall(I))
return;
break;
+ case LibFunc::mempcpy:
+ if (visitMemPCpyCall(I))
+ return;
+ break;
case LibFunc::memchr:
if (visitMemChrCall(I))
return;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index b9888ae..18c39d0 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -885,6 +885,7 @@
void visitPHI(const PHINode &I);
void visitCall(const CallInst &I);
bool visitMemCmpCall(const CallInst &I);
+ bool visitMemPCpyCall(const CallInst &I);
bool visitMemChrCall(const CallInst &I);
bool visitStrCpyCall(const CallInst &I, bool isStpcpy);
bool visitStrCmpCall(const CallInst &I);