[WebAssembly] Enable folding of offsets into global variable addresses.

llvm-svn: 254882

2 files changed, 11 insertions, 8 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
index 6e1283b4d33..85fb753ed0e 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -196,9 +196,8 @@ FastISel *WebAssemblyTargetLowering::createFastISel(
 
 bool WebAssemblyTargetLowering::isOffsetFoldingLegal(
     const GlobalAddressSDNode * /*GA*/) const {
-  // The WebAssembly target doesn't support folding offsets into global
-  // addresses.
-  return false;
+  // All offsets can be folded.
+  return true;
 }
 
 MVT WebAssemblyTargetLowering::getScalarShiftAmountTy(const DataLayout & /*DL*/,
@@ -528,13 +527,12 @@ SDValue WebAssemblyTargetLowering::LowerGlobalAddress(SDValue Op,
   SDLoc DL(Op);
   const auto *GA = cast<GlobalAddressSDNode>(Op);
   EVT VT = Op.getValueType();
-  assert(GA->getOffset() == 0 &&
-         "offsets on global addresses are forbidden by isOffsetFoldingLegal");
   assert(GA->getTargetFlags() == 0 && "WebAssembly doesn't set target flags");
   if (GA->getAddressSpace() != 0)
     fail(DL, DAG, "WebAssembly only expects the 0 address space");
   return DAG.getNode(WebAssemblyISD::Wrapper, DL, VT,
-                     DAG.getTargetGlobalAddress(GA->getGlobal(), DL, VT));
+                     DAG.getTargetGlobalAddress(GA->getGlobal(), DL, VT,
+                                                GA->getOffset()));
 }
 
 SDValue
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
index dd9358035a8..2d2adeb93d2 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
@@ -39,11 +39,16 @@ MCSymbol *WebAssemblyMCInstLower::GetExternalSymbolSymbol(
 
 MCOperand WebAssemblyMCInstLower::LowerSymbolOperand(const MachineOperand &MO,
                                                      MCSymbol *Sym) const {
+  assert(MO.getTargetFlags() == 0 && "WebAssembly does not use target flags");
 
   const MCExpr *Expr = MCSymbolRefExpr::create(Sym, Ctx);
 
-  if (!MO.isJTI() && MO.getOffset())
-    llvm_unreachable("unknown symbol op");
+  int64_t Offset = MO.getOffset();
+  if (Offset != 0) {
+    assert(!MO.isJTI() && "Unexpected offset with jump table index");
+    Expr =
+        MCBinaryExpr::createAdd(Expr, MCConstantExpr::create(Offset, Ctx), Ctx);
+  }
 
   return MCOperand::createExpr(Expr);
 }