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-rw-r--r--src/cmd/internal/obj/wasm/wasmobj.go65
1 files changed, 45 insertions, 20 deletions
diff --git a/src/cmd/internal/obj/wasm/wasmobj.go b/src/cmd/internal/obj/wasm/wasmobj.go
index 4b5324cc56..20ed142812 100644
--- a/src/cmd/internal/obj/wasm/wasmobj.go
+++ b/src/cmd/internal/obj/wasm/wasmobj.go
@@ -125,9 +125,10 @@ var Linkwasm = obj.LinkArch{
}
var (
- morestack *obj.LSym
- morestackNoCtxt *obj.LSym
- sigpanic *obj.LSym
+ morestack *obj.LSym
+ morestackNoCtxt *obj.LSym
+ sigpanic *obj.LSym
+ wasm_pc_f_loop_export *obj.LSym
)
const (
@@ -147,6 +148,7 @@ func instinit(ctxt *obj.Link) {
morestack = ctxt.Lookup("runtime.morestack")
morestackNoCtxt = ctxt.Lookup("runtime.morestack_noctxt")
sigpanic = ctxt.LookupABI("runtime.sigpanic", obj.ABIInternal)
+ wasm_pc_f_loop_export = ctxt.Lookup("wasm_pc_f_loop_export")
}
func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
@@ -825,13 +827,6 @@ func genWasmImportWrapper(s *obj.LSym, appendp func(p *obj.Prog, as obj.As, args
// https://github.com/WebAssembly/multi-value/blob/master/proposals/multi-value/Overview.md
panic("invalid results type") // impossible until multi-value proposal has landed
}
- if len(wi.Results) == 1 {
- // If we have a result (rather than returning nothing at all), then
- // we'll write the result to the Go stack relative to the current stack pointer.
- // We cache the current stack pointer value on the wasm stack here and then use
- // it after the Call instruction to store the result.
- p = appendp(p, AGet, regAddr(REG_SP))
- }
for _, f := range wi.Params {
// Each load instructions will consume the value of sp on the stack, so
// we need to read sp for each param. WASM appears to not have a stack dup instruction
@@ -878,20 +873,38 @@ func genWasmImportWrapper(s *obj.LSym, appendp func(p *obj.Prog, as obj.As, args
// to by 8 bytes to account for the return address on the Go stack.
storeOffset := f.Offset + 8
- // This code is paired the code above that reads the stack pointer onto the wasm
- // stack. We've done this so we have a consistent view of the sp value as it might
- // be manipulated by the call and we want to ignore that manipulation here.
+ // We need to push SP on the Wasm stack for the Store instruction, which needs to
+ // be pushed before the value (call result). So we pop the value into a register,
+ // push SP, and push the value back.
+ // We cannot get the SP onto the stack before the call, as if the host function
+ // calls back into Go, the Go stack may have moved.
switch f.Type {
case obj.WasmI32:
- p = appendp(p, AI32Store, constAddr(storeOffset))
+ p = appendp(p, AI64ExtendI32U) // the register is 64-bit, so we have to extend
+ p = appendp(p, ASet, regAddr(REG_R0))
+ p = appendp(p, AGet, regAddr(REG_SP))
+ p = appendp(p, AGet, regAddr(REG_R0))
+ p = appendp(p, AI64Store32, constAddr(storeOffset))
case obj.WasmI64:
+ p = appendp(p, ASet, regAddr(REG_R0))
+ p = appendp(p, AGet, regAddr(REG_SP))
+ p = appendp(p, AGet, regAddr(REG_R0))
p = appendp(p, AI64Store, constAddr(storeOffset))
case obj.WasmF32:
+ p = appendp(p, ASet, regAddr(REG_F0))
+ p = appendp(p, AGet, regAddr(REG_SP))
+ p = appendp(p, AGet, regAddr(REG_F0))
p = appendp(p, AF32Store, constAddr(storeOffset))
case obj.WasmF64:
+ p = appendp(p, ASet, regAddr(REG_F16))
+ p = appendp(p, AGet, regAddr(REG_SP))
+ p = appendp(p, AGet, regAddr(REG_F16))
p = appendp(p, AF64Store, constAddr(storeOffset))
case obj.WasmPtr:
p = appendp(p, AI64ExtendI32U)
+ p = appendp(p, ASet, regAddr(REG_R0))
+ p = appendp(p, AGet, regAddr(REG_SP))
+ p = appendp(p, AGet, regAddr(REG_R0))
p = appendp(p, AI64Store, constAddr(storeOffset))
default:
panic("bad result type")
@@ -907,10 +920,13 @@ func genWasmExportWrapper(s *obj.LSym, appendp func(p *obj.Prog, as obj.As, args
we := s.Func().WasmExport
we.CreateAuxSym()
p := s.Func().Text
+ framesize := p.To.Offset
+ for p.Link != nil && p.Link.As == obj.AFUNCDATA {
+ p = p.Link
+ }
if p.Link != nil {
panic("wrapper functions for WASM export should not have a body")
}
- framesize := p.To.Offset
// Store args
for i, f := range we.Params {
@@ -943,20 +959,25 @@ func genWasmExportWrapper(s *obj.LSym, appendp func(p *obj.Prog, as obj.As, args
p = appendp(p, ASet, regAddr(REG_SP))
// write return address to Go stack
p = appendp(p, AGet, regAddr(REG_SP))
- p = appendp(p, AI64Const, obj.Addr{
+ retAddr := obj.Addr{
Type: obj.TYPE_ADDR,
Name: obj.NAME_EXTERN,
Sym: s, // PC_F
Offset: 1, // PC_B=1, past the prologue, so we have the right SP delta
- })
+ }
+ p = appendp(p, AI64Const, retAddr)
p = appendp(p, AI64Store, constAddr(0))
// Set PC_B parameter to function entry
p = appendp(p, AI32Const, constAddr(0))
p = appendp(p, ACall, obj.Addr{Type: obj.TYPE_MEM, Name: obj.NAME_EXTERN, Sym: we.WrappedSym})
- // return value is on the top of the stack, indicating whether to unwind the Wasm stack
- // TODO: handle stack unwinding
+ // Return value is on the top of the stack, indicating whether to unwind the Wasm stack.
+ // In the unwinding case, we call wasm_pc_f_loop_export to handle stack switch and rewinding,
+ // until a normal return (non-unwinding) back to this function.
p = appendp(p, AIf)
- p = appendp(p, obj.AUNDEF)
+ p = appendp(p, AI32Const, retAddr)
+ p = appendp(p, AI32Const, constAddr(16))
+ p = appendp(p, AI32ShrU)
+ p = appendp(p, ACall, obj.Addr{Type: obj.TYPE_MEM, Name: obj.NAME_EXTERN, Sym: wasm_pc_f_loop_export})
p = appendp(p, AEnd)
// Load result
@@ -1008,6 +1029,7 @@ var notUsePC_B = map[string]bool{
"wasm_export_resume": true,
"wasm_export_getsp": true,
"wasm_pc_f_loop": true,
+ "wasm_pc_f_loop_export": true,
"gcWriteBarrier": true,
"runtime.gcWriteBarrier1": true,
"runtime.gcWriteBarrier2": true,
@@ -1062,6 +1084,9 @@ func assemble(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
"wasm_pc_f_loop", "runtime.wasmDiv", "runtime.wasmTruncS", "runtime.wasmTruncU", "memeqbody":
varDecls = []*varDecl{}
useAssemblyRegMap()
+ case "wasm_pc_f_loop_export":
+ varDecls = []*varDecl{{count: 2, typ: i32}}
+ useAssemblyRegMap()
case "memchr", "memcmp":
varDecls = []*varDecl{{count: 2, typ: i32}}
useAssemblyRegMap()
generated by cgit v1.3 (git 2.53.0) at 2026-04-16 00:47:45 +0000