[WebAssembly] Basic support for Wasm object file encoding.
With the "wasm32-unknown-unknown-wasm" triple, this allows writing out
simple wasm object files, and is another step in a larger series toward
migrating from ELF to general wasm object support. Note that this code
and the binary format itself is still experimental.
llvm-svn: 296190
diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
index 91583ef..a0b0089 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
@@ -13,6 +13,7 @@
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "MCTargetDesc/WebAssemblyFixupKinds.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/MC/MCCodeEmitter.h"
@@ -48,9 +49,7 @@
public:
WebAssemblyMCCodeEmitter(const MCInstrInfo &mcii, MCContext &ctx)
- : MCII(mcii), Ctx(ctx) {
- (void)Ctx;
- }
+ : MCII(mcii), Ctx(ctx) {}
};
} // end anonymous namespace
@@ -68,6 +67,13 @@
assert(Binary < UINT8_MAX && "Multi-byte opcodes not supported yet");
OS << uint8_t(Binary);
+ // For br_table instructions, encode the size of the table. In the MCInst,
+ // there's an index operand, one operand for each table entry, and the
+ // default operand.
+ if (MI.getOpcode() == WebAssembly::BR_TABLE_I32 ||
+ MI.getOpcode() == WebAssembly::BR_TABLE_I64)
+ encodeULEB128(MI.getNumOperands() - 2, OS);
+
const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
for (unsigned i = 0, e = MI.getNumOperands(); i < e; ++i) {
const MCOperand &MO = MI.getOperand(i);
@@ -82,6 +88,12 @@
encodeSLEB128(int32_t(MO.getImm()), OS);
} else if (Info.OperandType == WebAssembly::OPERAND_I64IMM) {
encodeSLEB128(int64_t(MO.getImm()), OS);
+ } else if (Info.OperandType == WebAssembly::OPERAND_GLOBAL) {
+ Fixups.push_back(MCFixup::create(
+ OS.tell() - Start, MCConstantExpr::create(MO.getImm(), Ctx),
+ MCFixupKind(WebAssembly::fixup_code_global_index), MI.getLoc()));
+ ++MCNumFixups;
+ encodeULEB128(uint64_t(MO.getImm()), OS);
} else {
encodeULEB128(uint64_t(MO.getImm()), OS);
}
@@ -107,14 +119,28 @@
support::endian::Writer<support::little>(OS).write<double>(d);
}
} else if (MO.isExpr()) {
+ const MCOperandInfo &Info = Desc.OpInfo[i];
+ llvm::MCFixupKind FixupKind;
+ size_t PaddedSize;
+ if (Info.OperandType == WebAssembly::OPERAND_I32IMM) {
+ FixupKind = MCFixupKind(WebAssembly::fixup_code_sleb128_i32);
+ PaddedSize = 5;
+ } else if (Info.OperandType == WebAssembly::OPERAND_I64IMM) {
+ FixupKind = MCFixupKind(WebAssembly::fixup_code_sleb128_i64);
+ PaddedSize = 10;
+ } else if (Info.OperandType == WebAssembly::OPERAND_FUNCTION32 ||
+ Info.OperandType == WebAssembly::OPERAND_OFFSET32 ||
+ Info.OperandType == WebAssembly::OPERAND_TYPEINDEX) {
+ FixupKind = MCFixupKind(WebAssembly::fixup_code_uleb128_i32);
+ PaddedSize = 5;
+ } else {
+ llvm_unreachable("unexpected symbolic operand kind");
+ }
Fixups.push_back(MCFixup::create(
OS.tell() - Start, MO.getExpr(),
- STI.getTargetTriple().isArch64Bit() ? FK_Data_8 : FK_Data_4,
- MI.getLoc()));
+ FixupKind, MI.getLoc()));
++MCNumFixups;
- encodeULEB128(STI.getTargetTriple().isArch64Bit() ? UINT64_MAX
- : uint64_t(UINT32_MAX),
- OS);
+ encodeULEB128(0, OS, PaddedSize - 1);
} else {
llvm_unreachable("unexpected operand kind");
}