[WebAssembly] Narrowing and widening SIMD ops

Summary:
Implements target-specific LLVM intrinsics and clang builtins for
these new SIMD operations, as described at https://github.com/WebAssembly/simd/blob/master/proposals/simd/SIMD.md#integer-to-integer-narrowing.

Reviewers: aheejin

Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D67425

llvm-svn: 371906
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 1b2468d..f40ced0 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -14196,6 +14196,63 @@
     Function *Callee = CGM.getIntrinsic(IntNo, A->getType());
     return Builder.CreateCall(Callee, {A, B, C});
   }
+  case WebAssembly::BI__builtin_wasm_narrow_s_i8x16_i16x8:
+  case WebAssembly::BI__builtin_wasm_narrow_u_i8x16_i16x8:
+  case WebAssembly::BI__builtin_wasm_narrow_s_i16x8_i32x4:
+  case WebAssembly::BI__builtin_wasm_narrow_u_i16x8_i32x4: {
+    Value *Low = EmitScalarExpr(E->getArg(0));
+    Value *High = EmitScalarExpr(E->getArg(1));
+    unsigned IntNo;
+    switch (BuiltinID) {
+    case WebAssembly::BI__builtin_wasm_narrow_s_i8x16_i16x8:
+    case WebAssembly::BI__builtin_wasm_narrow_s_i16x8_i32x4:
+      IntNo = Intrinsic::wasm_narrow_signed;
+      break;
+    case WebAssembly::BI__builtin_wasm_narrow_u_i8x16_i16x8:
+    case WebAssembly::BI__builtin_wasm_narrow_u_i16x8_i32x4:
+      IntNo = Intrinsic::wasm_narrow_unsigned;
+      break;
+    default:
+      llvm_unreachable("unexpected builtin ID");
+    }
+    Function *Callee =
+        CGM.getIntrinsic(IntNo, {ConvertType(E->getType()), Low->getType()});
+    return Builder.CreateCall(Callee, {Low, High});
+  }
+  case WebAssembly::BI__builtin_wasm_widen_low_s_i16x8_i8x16:
+  case WebAssembly::BI__builtin_wasm_widen_high_s_i16x8_i8x16:
+  case WebAssembly::BI__builtin_wasm_widen_low_u_i16x8_i8x16:
+  case WebAssembly::BI__builtin_wasm_widen_high_u_i16x8_i8x16:
+  case WebAssembly::BI__builtin_wasm_widen_low_s_i32x4_i16x8:
+  case WebAssembly::BI__builtin_wasm_widen_high_s_i32x4_i16x8:
+  case WebAssembly::BI__builtin_wasm_widen_low_u_i32x4_i16x8:
+  case WebAssembly::BI__builtin_wasm_widen_high_u_i32x4_i16x8: {
+    Value *Vec = EmitScalarExpr(E->getArg(0));
+    unsigned IntNo;
+    switch (BuiltinID) {
+    case WebAssembly::BI__builtin_wasm_widen_low_s_i16x8_i8x16:
+    case WebAssembly::BI__builtin_wasm_widen_low_s_i32x4_i16x8:
+      IntNo = Intrinsic::wasm_widen_low_signed;
+      break;
+    case WebAssembly::BI__builtin_wasm_widen_high_s_i16x8_i8x16:
+    case WebAssembly::BI__builtin_wasm_widen_high_s_i32x4_i16x8:
+      IntNo = Intrinsic::wasm_widen_high_signed;
+      break;
+    case WebAssembly::BI__builtin_wasm_widen_low_u_i16x8_i8x16:
+    case WebAssembly::BI__builtin_wasm_widen_low_u_i32x4_i16x8:
+      IntNo = Intrinsic::wasm_widen_low_unsigned;
+      break;
+    case WebAssembly::BI__builtin_wasm_widen_high_u_i16x8_i8x16:
+    case WebAssembly::BI__builtin_wasm_widen_high_u_i32x4_i16x8:
+      IntNo = Intrinsic::wasm_widen_high_unsigned;
+      break;
+    default:
+      llvm_unreachable("unexpected builtin ID");
+    }
+    Function *Callee =
+        CGM.getIntrinsic(IntNo, {ConvertType(E->getType()), Vec->getType()});
+    return Builder.CreateCall(Callee, Vec);
+  }
   default:
     return nullptr;
   }