Separate builtins for x84-64 and i386; implement __mulh and __umulh

Summary: We need x86-64-specific builtins if we want to implement some of the MS intrinsics - winnt.h contains definitions of some functions for i386, but not for x86-64 (for example _InterlockedOr64), which means that we cannot treat them as builtins for both i386 and x86-64, because then we have definitions of builtin functions in winnt.h on i386.

Reviewers: thakis, majnemer, hans, rnk

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D24598

llvm-svn: 283264

1 files changed, 24 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index e9248b35cd6..d05e910f244 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -7575,6 +7575,30 @@ Value *CodeGenFunction::EmitX86BuiltinExpr(unsigned BuiltinID,
     return getCmpIntrinsicCall(Intrinsic::x86_sse2_cmp_sd, 6);
   case X86::BI__builtin_ia32_cmpordsd:
     return getCmpIntrinsicCall(Intrinsic::x86_sse2_cmp_sd, 7);
+
+  case X86::BI__mulh:
+  case X86::BI__umulh: {
+    Value *LHS = EmitScalarExpr(E->getArg(0));
+    Value *RHS = EmitScalarExpr(E->getArg(1));
+    llvm::Type *ResType = ConvertType(E->getType());
+    llvm::Type *Int128Ty = llvm::IntegerType::get(getLLVMContext(), 128);
+
+    bool IsSigned = (BuiltinID == X86::BI__mulh);
+    LHS = Builder.CreateIntCast(LHS, Int128Ty, IsSigned);
+    RHS = Builder.CreateIntCast(RHS, Int128Ty, IsSigned);
+
+    Value *MulResult, *HigherBits;
+    if (IsSigned) {
+      MulResult = Builder.CreateNSWMul(LHS, RHS);
+      HigherBits = Builder.CreateAShr(MulResult, 64);
+    } else {
+      MulResult = Builder.CreateNUWMul(LHS, RHS);
+      HigherBits = Builder.CreateLShr(MulResult, 64);
+    }
+
+    HigherBits = Builder.CreateIntCast(HigherBits, ResType, IsSigned);
+    return HigherBits;
+  }
   }
 }