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pccpcc
committedJan 24, 2018
IRGen: Emit an inline implementation of __builtin_wmemcmp on MSVCRT platforms.
The MSVC runtime library does not provide a definition of wmemcmp, so we need an inline implementation. Differential Revision: https://reviews.llvm.org/D42441 llvm-svn: 323362
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‎clang/lib/CodeGen/CGBuiltin.cpp

+57
Original file line numberDiff line numberDiff line change
@@ -1741,6 +1741,63 @@ RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
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Builder.CreateMemSet(Dest, ByteVal, SizeVal, false);
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return RValue::get(Dest.getPointer());
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}
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case Builtin::BI__builtin_wmemcmp: {
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// The MSVC runtime library does not provide a definition of wmemcmp, so we
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// need an inline implementation.
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if (!getTarget().getTriple().isOSMSVCRT())
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break;
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llvm::Type *WCharTy = ConvertType(getContext().WCharTy);
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Value *Dst = EmitScalarExpr(E->getArg(0));
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Value *Src = EmitScalarExpr(E->getArg(1));
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Value *Size = EmitScalarExpr(E->getArg(2));
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BasicBlock *Entry = Builder.GetInsertBlock();
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BasicBlock *CmpGT = createBasicBlock("wmemcmp.gt");
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BasicBlock *CmpLT = createBasicBlock("wmemcmp.lt");
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BasicBlock *Next = createBasicBlock("wmemcmp.next");
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BasicBlock *Exit = createBasicBlock("wmemcmp.exit");
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Value *SizeEq0 = Builder.CreateICmpEQ(Size, ConstantInt::get(SizeTy, 0));
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Builder.CreateCondBr(SizeEq0, Exit, CmpGT);
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EmitBlock(CmpGT);
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PHINode *DstPhi = Builder.CreatePHI(Dst->getType(), 2);
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DstPhi->addIncoming(Dst, Entry);
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PHINode *SrcPhi = Builder.CreatePHI(Src->getType(), 2);
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SrcPhi->addIncoming(Src, Entry);
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PHINode *SizePhi = Builder.CreatePHI(SizeTy, 2);
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SizePhi->addIncoming(Size, Entry);
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CharUnits WCharAlign =
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getContext().getTypeAlignInChars(getContext().WCharTy);
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Value *DstCh = Builder.CreateAlignedLoad(WCharTy, DstPhi, WCharAlign);
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Value *SrcCh = Builder.CreateAlignedLoad(WCharTy, SrcPhi, WCharAlign);
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Value *DstGtSrc = Builder.CreateICmpUGT(DstCh, SrcCh);
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Builder.CreateCondBr(DstGtSrc, Exit, CmpLT);
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EmitBlock(CmpLT);
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Value *DstLtSrc = Builder.CreateICmpULT(DstCh, SrcCh);
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Builder.CreateCondBr(DstLtSrc, Exit, Next);
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EmitBlock(Next);
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Value *NextDst = Builder.CreateConstInBoundsGEP1_32(WCharTy, DstPhi, 1);
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Value *NextSrc = Builder.CreateConstInBoundsGEP1_32(WCharTy, SrcPhi, 1);
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Value *NextSize = Builder.CreateSub(SizePhi, ConstantInt::get(SizeTy, 1));
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Value *NextSizeEq0 =
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Builder.CreateICmpEQ(NextSize, ConstantInt::get(SizeTy, 0));
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Builder.CreateCondBr(NextSizeEq0, Exit, CmpGT);
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DstPhi->addIncoming(NextDst, Next);
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SrcPhi->addIncoming(NextSrc, Next);
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SizePhi->addIncoming(NextSize, Next);
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EmitBlock(Exit);
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PHINode *Ret = Builder.CreatePHI(IntTy, 4);
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Ret->addIncoming(ConstantInt::get(IntTy, 0), Entry);
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Ret->addIncoming(ConstantInt::get(IntTy, 1), CmpGT);
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Ret->addIncoming(ConstantInt::get(IntTy, -1), CmpLT);
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Ret->addIncoming(ConstantInt::get(IntTy, 0), Next);
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return RValue::get(Ret);
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}
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case Builtin::BI__builtin_dwarf_cfa: {
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// The offset in bytes from the first argument to the CFA.
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//

‎clang/test/CodeGen/wmemcmp.c

+37
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,37 @@
1+
// RUN: %clang_cc1 %s -triple x86_64-pc-win32 -emit-llvm -o - | FileCheck %s
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typedef __SIZE_TYPE__ size_t;
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typedef __WCHAR_TYPE__ wchar_t;
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int wmemcmp_test(const wchar_t *s1, const wchar_t *s2, size_t n) {
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// CHECK: [[S1:%.*]] = load
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// CHECK: [[S2:%.*]] = load
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// CHECK: [[N:%.*]] = load
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// CHECK: [[N0:%.*]] = icmp eq i64 [[N]], 0
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// CHECK: br i1 [[N0]], label %[[EXIT:.*]], label %[[GT:.*]]
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// CHECK: [[GT]]:
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// CHECK: [[S1P:%.*]] = phi i16* [ [[S1]], %[[ENTRY:.*]] ], [ [[S1N:.*]], %[[NEXT:.*]] ]
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// CHECK: [[S2P:%.*]] = phi i16* [ [[S2]], %[[ENTRY]] ], [ [[S2N:.*]], %[[NEXT]] ]
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// CHECK: [[NP:%.*]] = phi i64 [ [[N]], %[[ENTRY]] ], [ [[NN:.*]], %[[NEXT]] ]
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// CHECK: [[S1L:%.*]] = load i16, i16* [[S1P]], align 2
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// CHECK: [[S2L:%.*]] = load i16, i16* [[S2P]], align 2
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// CHECK: [[CMPGT:%.*]] = icmp ugt i16 [[S1L]], [[S2L]]
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// CHECK: br i1 [[CMPGT]], label %[[EXIT]], label %[[LT:.*]]
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// CHECK: [[LT]]:
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// CHECK: [[CMPLT:%.*]] = icmp ult i16 [[S1L]], [[S2L]]
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// CHECK: br i1 [[CMPLT]], label %[[EXIT]], label %[[NEXT:.*]]
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// CHECK: [[NEXT]]:
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// CHECK: [[S1N]] = getelementptr inbounds i16, i16* [[S1P]], i32 1
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// CHECK: [[S2N]] = getelementptr inbounds i16, i16* [[S2P]], i32 1
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// CHECK: [[NN]] = sub i64 [[NP]], 1
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// CHECK: [[NN0:%.*]] = icmp eq i64 [[NN]], 0
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// CHECK: br i1 [[NN0]], label %[[EXIT]], label %[[GT]]
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//
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// CHECK: [[EXIT]]:
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// CHECK: [[RV:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ 1, %[[GT]] ], [ -1, %[[LT]] ], [ 0, %[[NEXT]] ]
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// CHECK: ret i32 [[RV]]
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return __builtin_wmemcmp(s1, s2, n);
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}

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