[WebAssembly] SIMD Load and extend operations

Summary:
As specified at
https://github.com/webassembly/simd/blob/master/proposals/simd/SIMD.md#load-and-extend.
These instructions are behind the unimplemented-simd128 target feature
for now because they have not been implemented in V8 yet.

Reviewers: aheejin

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68058

llvm-svn: 373040

1 files changed, 19 insertions, 1 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
index 8528d930d21..53ca7d77ca0 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -228,7 +228,7 @@ WebAssemblyTargetLowering::WebAssemblyTargetLowering(
   //  - Floating-point extending loads.
   //  - Floating-point truncating stores.
   //  - i1 extending loads.
-  //  - extending/truncating SIMD loads/stores
+  //  - truncating SIMD stores and most extending loads
   setLoadExtAction(ISD::EXTLOAD, MVT::f64, MVT::f32, Expand);
   setTruncStoreAction(MVT::f64, MVT::f32, Expand);
   for (auto T : MVT::integer_valuetypes())
@@ -245,6 +245,14 @@ WebAssemblyTargetLowering::WebAssemblyTargetLowering(
         }
       }
     }
+    // But some vector extending loads are legal
+    if (Subtarget->hasUnimplementedSIMD128()) {
+      for (auto Ext : {ISD::EXTLOAD, ISD::SEXTLOAD, ISD::ZEXTLOAD}) {
+        setLoadExtAction(Ext, MVT::v8i16, MVT::v8i8, Legal);
+        setLoadExtAction(Ext, MVT::v4i32, MVT::v4i16, Legal);
+        setLoadExtAction(Ext, MVT::v2i64, MVT::v2i32, Legal);
+      }
+    }
   }
 
   // Don't do anything clever with build_pairs
@@ -540,6 +548,16 @@ bool WebAssemblyTargetLowering::isIntDivCheap(EVT VT,
   return true;
 }
 
+bool WebAssemblyTargetLowering::isVectorLoadExtDesirable(SDValue ExtVal) const {
+  if (!Subtarget->hasUnimplementedSIMD128())
+    return false;
+  MVT ExtT = ExtVal.getSimpleValueType();
+  MVT MemT = cast<LoadSDNode>(ExtVal->getOperand(0))->getSimpleValueType(0);
+  return (ExtT == MVT::v8i16 && MemT == MVT::v8i8) ||
+         (ExtT == MVT::v4i32 && MemT == MVT::v4i16) ||
+         (ExtT == MVT::v2i64 && MemT == MVT::v2i32);
+}
+
 EVT WebAssemblyTargetLowering::getSetCCResultType(const DataLayout &DL,
                                                   LLVMContext &C,
                                                   EVT VT) const {