[llvm] [WebAssembly] Support binary generation for new EH (PR #109027)
Heejin Ahn via llvm-commits
llvm-commits at lists.llvm.org
Tue Sep 17 11:41:08 PDT 2024
https://github.com/aheejin created https://github.com/llvm/llvm-project/pull/109027
This adds support for binary generation for the new EH proposal.
So far the only case that we emitted variable immediate operands in binary has been `br_table`'s destinations. (Other `variable_ops` uses in TableGen files are register operands, such as the operands of `call`, so they don't get emitted in binary as a part of the same instruction.)
With this PR, variable immediate operands can include `try_table`'s operands:
- # of catch clauses
- catch clauses sub-opcodes
- `catch`: 0x00
- `catch_ref`: 0x01
- `catch_all`: 0x02
- `catch_all_ref`: 0x03
- catch clauses' destinations
With `try_table`, we now have variable expr operands for `try_table`'s catch clauses' tags. We treat their fixups in the same way we do for tags in other instructions such as in `throw`.
Diff without whitespace will be easier to view.
>From 36a7c02526ad501a196870b802e3747a96116bbc Mon Sep 17 00:00:00 2001
From: Heejin Ahn <aheejin at gmail.com>
Date: Sun, 15 Sep 2024 07:37:18 +0000
Subject: [PATCH] [WebAssembly] Support binary generation for new EH
This adds support for binary generation for the new EH proposal.
So far the only case that we emitted variable immediate operands in
binary has been `br_table`'s destinations. (Other `variable_ops` uses in
TableGen files are register operands, such as the operands of `call`, so
they don't get emitted in binary as a part of the same instruction.)
With this PR, variable immediate operands can include `try_table`'s
operands:
- # of catch clauses
- catch clauses sub-opcodes
- `catch`: 0x00
- `catch_ref`: 0x01
- `catch_all`: 0x02
- `catch_all_ref`: 0x03
- catch clauses' destinations
With `try_table`, we now have variable expr operands for `try_table`'s
catch clauses' tags. We treat their fixups in the same way we do for
tags in other instructions such as in `throw`.
Diff without whitespace will be easier to view.
---
.../MCTargetDesc/WebAssemblyMCCodeEmitter.cpp | 70 +++++++++++--------
llvm/test/CodeGen/WebAssembly/exception.ll | 1 +
llvm/test/MC/WebAssembly/eh-assembly.s | 2 +
3 files changed, 44 insertions(+), 29 deletions(-)
diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
index aaca213c4afe9b..3e7487dbd8f54e 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
@@ -82,14 +82,15 @@ void WebAssemblyMCCodeEmitter::encodeInstruction(
// For br_table instructions, encode the size of the table. In the MCInst,
// there's an index operand (if not a stack instruction), one operand for
// each table entry, and the default operand.
- if (MI.getOpcode() == WebAssembly::BR_TABLE_I32_S ||
- MI.getOpcode() == WebAssembly::BR_TABLE_I64_S)
+ unsigned Opcode = MI.getOpcode();
+ if (Opcode == WebAssembly::BR_TABLE_I32_S ||
+ Opcode == WebAssembly::BR_TABLE_I64_S)
encodeULEB128(MI.getNumOperands() - 1, OS);
- if (MI.getOpcode() == WebAssembly::BR_TABLE_I32 ||
- MI.getOpcode() == WebAssembly::BR_TABLE_I64)
+ if (Opcode == WebAssembly::BR_TABLE_I32 ||
+ Opcode == WebAssembly::BR_TABLE_I64)
encodeULEB128(MI.getNumOperands() - 2, OS);
- const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
+ const MCInstrDesc &Desc = MCII.get(Opcode);
for (unsigned I = 0, E = MI.getNumOperands(); I < E; ++I) {
const MCOperand &MO = MI.getOperand(I);
if (MO.isReg()) {
@@ -136,7 +137,12 @@ void WebAssemblyMCCodeEmitter::encodeInstruction(
encodeULEB128(uint64_t(MO.getImm()), OS);
}
} else {
- encodeULEB128(uint64_t(MO.getImm()), OS);
+ // Variadic immediate operands are br_table's destination operands or
+ // try_table's operands (# of catch clauses, catch sub-opcodes, or catch
+ // clause destinations)
+ assert(WebAssembly::isBrTable(Opcode) ||
+ Opcode == WebAssembly::TRY_TABLE_S);
+ encodeULEB128(uint32_t(MO.getImm()), OS);
}
} else if (MO.isSFPImm()) {
@@ -146,32 +152,38 @@ void WebAssemblyMCCodeEmitter::encodeInstruction(
uint64_t D = MO.getDFPImm();
support::endian::write<uint64_t>(OS, D, llvm::endianness::little);
} else if (MO.isExpr()) {
- const MCOperandInfo &Info = Desc.operands()[I];
llvm::MCFixupKind FixupKind;
size_t PaddedSize = 5;
- switch (Info.OperandType) {
- case WebAssembly::OPERAND_I32IMM:
- FixupKind = MCFixupKind(WebAssembly::fixup_sleb128_i32);
- break;
- case WebAssembly::OPERAND_I64IMM:
- FixupKind = MCFixupKind(WebAssembly::fixup_sleb128_i64);
- PaddedSize = 10;
- break;
- case WebAssembly::OPERAND_FUNCTION32:
- case WebAssembly::OPERAND_TABLE:
- case WebAssembly::OPERAND_OFFSET32:
- case WebAssembly::OPERAND_SIGNATURE:
- case WebAssembly::OPERAND_TYPEINDEX:
- case WebAssembly::OPERAND_GLOBAL:
- case WebAssembly::OPERAND_TAG:
+ if (I < Desc.getNumOperands()) {
+ const MCOperandInfo &Info = Desc.operands()[I];
+ switch (Info.OperandType) {
+ case WebAssembly::OPERAND_I32IMM:
+ FixupKind = MCFixupKind(WebAssembly::fixup_sleb128_i32);
+ break;
+ case WebAssembly::OPERAND_I64IMM:
+ FixupKind = MCFixupKind(WebAssembly::fixup_sleb128_i64);
+ PaddedSize = 10;
+ break;
+ case WebAssembly::OPERAND_FUNCTION32:
+ case WebAssembly::OPERAND_TABLE:
+ case WebAssembly::OPERAND_OFFSET32:
+ case WebAssembly::OPERAND_SIGNATURE:
+ case WebAssembly::OPERAND_TYPEINDEX:
+ case WebAssembly::OPERAND_GLOBAL:
+ case WebAssembly::OPERAND_TAG:
+ FixupKind = MCFixupKind(WebAssembly::fixup_uleb128_i32);
+ break;
+ case WebAssembly::OPERAND_OFFSET64:
+ FixupKind = MCFixupKind(WebAssembly::fixup_uleb128_i64);
+ PaddedSize = 10;
+ break;
+ default:
+ llvm_unreachable("unexpected symbolic operand kind");
+ }
+ } else {
+ // Variadic expr operands are try_table's catch/catch_ref clauses' tags.
+ assert(Opcode == WebAssembly::TRY_TABLE_S);
FixupKind = MCFixupKind(WebAssembly::fixup_uleb128_i32);
- break;
- case WebAssembly::OPERAND_OFFSET64:
- FixupKind = MCFixupKind(WebAssembly::fixup_uleb128_i64);
- PaddedSize = 10;
- break;
- default:
- llvm_unreachable("unexpected symbolic operand kind");
}
Fixups.push_back(MCFixup::create(OS.tell() - Start, MO.getExpr(),
FixupKind, MI.getLoc()));
diff --git a/llvm/test/CodeGen/WebAssembly/exception.ll b/llvm/test/CodeGen/WebAssembly/exception.ll
index 7259761d6313b6..1ad4c84f1c0237 100644
--- a/llvm/test/CodeGen/WebAssembly/exception.ll
+++ b/llvm/test/CodeGen/WebAssembly/exception.ll
@@ -1,6 +1,7 @@
; RUN: llc < %s -asm-verbose=false -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling -wasm-enable-exnref -verify-machineinstrs | FileCheck --implicit-check-not=ehgcr -allow-deprecated-dag-overlap %s
; RUN: llc < %s -asm-verbose=false -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling -wasm-enable-exnref -verify-machineinstrs -O0
; RUN: llc < %s -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling -wasm-enable-exnref
+; RUN: llc < %s -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling -wasm-enable-exnref -filetype=obj
target triple = "wasm32-unknown-unknown"
diff --git a/llvm/test/MC/WebAssembly/eh-assembly.s b/llvm/test/MC/WebAssembly/eh-assembly.s
index a769bc447d0ba9..b4d6b324d96e3e 100644
--- a/llvm/test/MC/WebAssembly/eh-assembly.s
+++ b/llvm/test/MC/WebAssembly/eh-assembly.s
@@ -1,4 +1,6 @@
# RUN: llvm-mc -triple=wasm32-unknown-unknown -mattr=+exception-handling --no-type-check < %s | FileCheck %s
+# Check that it converts to .o without errors, but don't check any output:
+# RUN: llvm-mc -triple=wasm32-unknown-unknown -filetype=obj -mattr=+exception-handling --no-type-check -o %t.o < %s
.tagtype __cpp_exception i32
.tagtype __c_longjmp i32
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