[PATCH] D43365: [WebAssembly] MC: Make explicit our current lack of support for relocations against unnamed temporary symbols.
Sam Clegg via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Feb 15 17:31:22 PST 2018
sbc100 created this revision.
Herald added subscribers: llvm-commits, sunfish, aheejin, jgravelle-google, dschuff, jfb.
Add an explict check before looking up symbol in SymbolIndices.
This was previously silently succeeding and returning zero for such
unnamed temporaries.
Repository:
rL LLVM
https://reviews.llvm.org/D43365
Files:
lib/MC/WasmObjectWriter.cpp
test/MC/WebAssembly/blockaddress.ll
Index: test/MC/WebAssembly/blockaddress.ll
===================================================================
--- /dev/null
+++ test/MC/WebAssembly/blockaddress.ll
@@ -0,0 +1,15 @@
+; TODO(sbc): Make this test pass by adding support for unnamed tempoaries
+; in wasm relocations.
+; RUN: not llc -filetype=obj %s
+
+target triple = "wasm32-unknown-unknown-wasm"
+
+ at foo = internal global i8* blockaddress(@bar, %addr), align 4
+
+define hidden i32 @bar() #0 {
+entry:
+ br label %addr
+
+addr:
+ ret i32 0
+}
Index: lib/MC/WasmObjectWriter.cpp
===================================================================
--- lib/MC/WasmObjectWriter.cpp
+++ lib/MC/WasmObjectWriter.cpp
@@ -347,14 +347,19 @@
bool IsPCRel = Backend.getFixupKindInfo(Fixup.getKind()).Flags &
MCFixupKindInfo::FKF_IsPCRel;
const auto &FixupSection = cast<MCSectionWasm>(*Fragment->getParent());
+
uint64_t C = Target.getConstant();
uint64_t FixupOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
MCContext &Ctx = Asm.getContext();
// The .init_array isn't translated as data, so don't do relocations in it.
if (FixupSection.getSectionName().startswith(".init_array"))
return;
+ // TODO(sbc): Add support for debug sections.
+ if (FixupSection.getKind().isMetadata())
+ return;
+
if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
assert(RefB->getKind() == MCSymbolRefExpr::VK_None &&
"Should not have constructed this");
@@ -423,12 +428,20 @@
WasmRelocationEntry Rec(FixupOffset, SymA, C, Type, &FixupSection);
DEBUG(dbgs() << "WasmReloc: " << Rec << "\n");
+ // Relocation other than R_WEBASSEMBLY_TYPE_INDEX_LEB are currently required
+ // to be against a named symbol.
+ // TODO(sbc): Add support for relocations against unnamed temporaries such
+ // as those generated by llvm's `blockaddress`.
+ // See: test/MC/WebAssembly/blockaddress.ll
+ if (SymA->getName().empty() && Type != wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB)
+ report_fatal_error("relocations against un-named temporaries are not yet "
+ "supported by wasm");
+
if (FixupSection.isWasmData())
DataRelocations.push_back(Rec);
else if (FixupSection.getKind().isText())
CodeRelocations.push_back(Rec);
- else if (!FixupSection.getKind().isMetadata())
- // TODO(sbc): Add support for debug sections.
+ else
llvm_unreachable("unexpected section type");
}
@@ -496,6 +509,9 @@
if (!Sym->isDefined())
return 0;
+ if (!SymbolIndices.count(Sym))
+ report_fatal_error("symbol not found in function/global index space: " +
+ Sym->getName());
uint32_t GlobalIndex = SymbolIndices[Sym];
const WasmGlobal& Global = Globals[GlobalIndex - NumGlobalImports];
uint64_t Address = Global.InitialValue + RelEntry.Addend;
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D43365.134535.patch
Type: text/x-patch
Size: 2855 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180216/8d54f1a6/attachment.bin>
More information about the llvm-commits
mailing list