[WebAssembly] Implement prolog/epilog insertion and FrameIndex elimination
Summary:
Use the SP32 physical register as the base for FrameIndex
lowering. Update it and the __stack_pointer global var in the prolog and
epilog. Extend the mapping of virtual registers to wasm locals to
include the physical registers.
Rather than modify the target-independent PrologEpilogInserter (which
asserts that there are no virtual registers left) include a
slightly-modified copy for Wasm that does not have this assertion and
only clears the virtual registers if scavenging was needed (which of
course it isn't for wasm).
Differential Revision: http://reviews.llvm.org/D15344
llvm-svn: 255392
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
index 76df63b..a5ca08f 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -167,6 +167,8 @@
setOperationAction(ISD::STACKRESTORE, MVT::Other, Expand);
setOperationAction(ISD::DYNAMIC_STACKALLOC, MVTPtr, Expand);
+ setOperationAction(ISD::FrameIndex, MVT::i32, Custom);
+
// Expand these forms; we pattern-match the forms that we can handle in isel.
for (auto T : {MVT::i32, MVT::i64, MVT::f32, MVT::f64})
for (auto Op : {ISD::BR_CC, ISD::SELECT_CC})
@@ -520,6 +522,8 @@
default:
llvm_unreachable("unimplemented operation lowering");
return SDValue();
+ case ISD::FrameIndex:
+ return LowerFrameIndex(Op, DAG);
case ISD::GlobalAddress:
return LowerGlobalAddress(Op, DAG);
case ISD::ExternalSymbol:
@@ -533,6 +537,12 @@
}
}
+SDValue WebAssemblyTargetLowering::LowerFrameIndex(SDValue Op,
+ SelectionDAG &DAG) const {
+ int FI = cast<FrameIndexSDNode>(Op)->getIndex();
+ return DAG.getTargetFrameIndex(FI, Op.getValueType());
+}
+
SDValue WebAssemblyTargetLowering::LowerGlobalAddress(SDValue Op,
SelectionDAG &DAG) const {
SDLoc DL(Op);