[lld] r360165 - [WebAssembly] Don't generate unused table entries.
Sam Clegg via llvm-commits
llvm-commits at lists.llvm.org
Tue May 7 08:46:30 PDT 2019
Author: sbc
Date: Tue May 7 08:46:30 2019
New Revision: 360165
URL: http://llvm.org/viewvc/llvm-project?rev=360165&view=rev
Log:
[WebAssembly] Don't generate unused table entries.
When generating PIC output only relocations of type
R_WASM_TABLE_INDEX_REL_SLEB should generate table entries.
R_WASM_TABLE_INDEX_I32 get resolved at runtime via the auto-generated
__wasm_apply_relocs functions.
R_WASM_TABLE_INDEX_SLEB are not allowed in PIC code.
Differential Revision: https://reviews.llvm.org/D61539
Modified:
lld/trunk/test/wasm/pie.ll
lld/trunk/test/wasm/shared.ll
lld/trunk/wasm/InputFiles.cpp
lld/trunk/wasm/Writer.cpp
Modified: lld/trunk/test/wasm/pie.ll
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/wasm/pie.ll?rev=360165&r1=360164&r2=360165&view=diff
==============================================================================
--- lld/trunk/test/wasm/pie.ll (original)
+++ lld/trunk/test/wasm/pie.ll Tue May 7 08:46:30 2019
@@ -38,7 +38,7 @@ define void @_start() {
; CHECK-NEXT: Table:
; CHECK-NEXT: ElemType: FUNCREF
; CHECK-NEXT: Limits:
-; CHECK-NEXT: Initial: 0x00000001
+; CHECK-NEXT: Initial: 0x00000000
; CHECK-NEXT: - Module: env
; CHECK-NEXT: Field: __memory_base
; CHECK-NEXT: Kind: GLOBAL
Modified: lld/trunk/test/wasm/shared.ll
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/wasm/shared.ll?rev=360165&r1=360164&r2=360165&view=diff
==============================================================================
--- lld/trunk/test/wasm/shared.ll (original)
+++ lld/trunk/test/wasm/shared.ll Tue May 7 08:46:30 2019
@@ -54,7 +54,7 @@ declare void @func_external()
; CHECK-NEXT: Name: dylink
; CHECK-NEXT: MemorySize: 24
; CHECK-NEXT: MemoryAlignment: 2
-; CHECK-NEXT: TableSize: 3
+; CHECK-NEXT: TableSize: 1
; CHECK-NEXT: TableAlignment: 0
; CHECK-NEXT: Needed: []
; CHECK-NEXT: - Type: TYPE
@@ -74,7 +74,7 @@ declare void @func_external()
; CHECK-NEXT: Table:
; CHECK-NEXT: ElemType: FUNCREF
; CHECK-NEXT: Limits:
-; CHECK-NEXT: Initial: 0x00000003
+; CHECK-NEXT: Initial: 0x00000001
; CHECK-NEXT: - Module: env
; CHECK-NEXT: Field: __stack_pointer
; CHECK-NEXT: Kind: GLOBAL
@@ -124,7 +124,7 @@ declare void @func_external()
; CHECK-NEXT: - Offset:
; CHECK-NEXT: Opcode: GLOBAL_GET
; CHECK-NEXT: Index: 2
-; CHECK-NEXT: Functions: [ 5, 3, 0 ]
+; CHECK-NEXT: Functions: [ 5 ]
; check the generated code in __wasm_call_ctors and __wasm_apply_relocs functions
; TODO(sbc): Disassemble and verify instructions.
@@ -136,7 +136,7 @@ declare void @func_external()
; CHECK-NEXT: Body: 10020B
; CHECK-NEXT: - Index: 2
; CHECK-NEXT: Locals: []
-; CHECK-NEXT: Body: 230141046A230241016A360200230141086A23043602002301410C6A230141006A360200230141106A2303360200230141146A230541046A3602000B
+; CHECK-NEXT: Body: 230141046A230241006A360200230141086A23043602002301410C6A230141006A360200230141106A2303360200230141146A230541046A3602000B
; check the data segment initialized with __memory_base global as offset
@@ -147,4 +147,4 @@ declare void @func_external()
; CHECK-NEXT: Offset:
; CHECK-NEXT: Opcode: GLOBAL_GET
; CHECK-NEXT: Index: 1
-; CHECK-NEXT: Content: '020000000100000002000000000000000000000000000000'
+; CHECK-NEXT: Content: '020000000000000000000000000000000000000000000000'
Modified: lld/trunk/wasm/InputFiles.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/wasm/InputFiles.cpp?rev=360165&r1=360164&r2=360165&view=diff
==============================================================================
--- lld/trunk/wasm/InputFiles.cpp (original)
+++ lld/trunk/wasm/InputFiles.cpp Tue May 7 08:46:30 2019
@@ -171,6 +171,8 @@ uint32_t ObjFile::calcNewValue(const Was
case R_WASM_TABLE_INDEX_I32:
case R_WASM_TABLE_INDEX_SLEB:
case R_WASM_TABLE_INDEX_REL_SLEB:
+ if (Config->Pic && !getFunctionSymbol(Reloc.Index)->hasTableIndex())
+ return 0;
return getFunctionSymbol(Reloc.Index)->getTableIndex();
case R_WASM_MEMORY_ADDR_SLEB:
case R_WASM_MEMORY_ADDR_I32:
Modified: lld/trunk/wasm/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/wasm/Writer.cpp?rev=360165&r1=360164&r2=360165&view=diff
==============================================================================
--- lld/trunk/wasm/Writer.cpp (original)
+++ lld/trunk/wasm/Writer.cpp Tue May 7 08:46:30 2019
@@ -1148,35 +1148,40 @@ void Writer::processRelocations(InputChu
ObjFile *File = Chunk->File;
ArrayRef<WasmSignature> Types = File->getWasmObj()->types();
for (const WasmRelocation &Reloc : Chunk->getRelocations()) {
+ if (Reloc.Type == R_WASM_TYPE_INDEX_LEB) {
+ // Mark target type as live
+ File->TypeMap[Reloc.Index] = registerType(Types[Reloc.Index]);
+ File->TypeIsUsed[Reloc.Index] = true;
+ continue;
+ }
+
+ // Other relocation types all have a corresponding symbol
+ auto *Sym = File->getSymbols()[Reloc.Index];
switch (Reloc.Type) {
case R_WASM_TABLE_INDEX_I32:
case R_WASM_TABLE_INDEX_SLEB:
case R_WASM_TABLE_INDEX_REL_SLEB: {
- FunctionSymbol *Sym = File->getFunctionSymbol(Reloc.Index);
- if (Sym->hasTableIndex() || !Sym->hasFunctionIndex())
- continue;
- Sym->setTableIndex(TableBase + IndirectFunctions.size());
- IndirectFunctions.emplace_back(Sym);
+ if (Config->Pic && Reloc.Type != R_WASM_TABLE_INDEX_REL_SLEB)
+ break;
+ auto *F = cast<FunctionSymbol>(Sym);
+ if (F->hasTableIndex() || !F->hasFunctionIndex())
+ break;
+ F->setTableIndex(TableBase + IndirectFunctions.size());
+ IndirectFunctions.emplace_back(F);
break;
}
case R_WASM_TYPE_INDEX_LEB:
- // Mark target type as live
- File->TypeMap[Reloc.Index] = registerType(Types[Reloc.Index]);
- File->TypeIsUsed[Reloc.Index] = true;
break;
- case R_WASM_GLOBAL_INDEX_LEB: {
- auto* Sym = File->getSymbols()[Reloc.Index];
+ case R_WASM_GLOBAL_INDEX_LEB:
if (!isa<GlobalSymbol>(Sym) && !Sym->isInGOT()) {
Sym->setGOTIndex(NumImportedGlobals++);
GOTSymbols.push_back(Sym);
}
break;
- }
case R_WASM_MEMORY_ADDR_SLEB:
case R_WASM_MEMORY_ADDR_LEB:
- case R_WASM_MEMORY_ADDR_REL_SLEB: {
+ case R_WASM_MEMORY_ADDR_REL_SLEB:
if (!Config->Relocatable) {
- auto* Sym = File->getSymbols()[Reloc.Index];
if (Sym->isUndefined() && !Sym->isWeak()) {
error(toString(File) + ": cannot resolve relocation of type " +
relocTypeToString(Reloc.Type) +
@@ -1185,34 +1190,29 @@ void Writer::processRelocations(InputChu
}
break;
}
- }
if (Config->Pic) {
switch (Reloc.Type) {
case R_WASM_TABLE_INDEX_SLEB:
case R_WASM_MEMORY_ADDR_SLEB:
- case R_WASM_MEMORY_ADDR_LEB: {
+ case R_WASM_MEMORY_ADDR_LEB:
// Certain relocation types can't be used when building PIC output, since
// they would require absolute symbol addresses at link time.
- Symbol *Sym = File->getSymbols()[Reloc.Index];
error(toString(File) + ": relocation " +
relocTypeToString(Reloc.Type) + " cannot be used againt symbol " +
toString(*Sym) + "; recompile with -fPIC");
break;
- }
case R_WASM_TABLE_INDEX_I32:
- case R_WASM_MEMORY_ADDR_I32: {
+ case R_WASM_MEMORY_ADDR_I32:
// These relocation types are only present in the data section and
// will be converted into code by `generateRelocationCode`. This code
// requires the symbols to have GOT entires.
- auto* Sym = File->getSymbols()[Reloc.Index];
if (!Sym->isHidden() && !Sym->isLocal() && !Sym->isInGOT()) {
Sym->setGOTIndex(NumImportedGlobals++);
GOTSymbols.push_back(Sym);
}
break;
}
- }
}
}
}
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