[llvm-branch-commits] [llvm] release/19.x: [WebAssembly] Handle symbols in `.init_array` sections (#119127) (PR #119533)
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Wed Dec 11 06:45:33 PST 2024
https://github.com/llvmbot updated https://github.com/llvm/llvm-project/pull/119533
>From eb67a306c640a1458d283ff8198c77df98f201b4 Mon Sep 17 00:00:00 2001
From: George Stagg <georgestagg at gmail.com>
Date: Wed, 4 Dec 2024 21:12:15 +0000
Subject: [PATCH 1/2] [WebAssembly] Support multiple `.init_array` fragments
when writing Wasm objects (#111008)
(cherry picked from commit ac5dd455caaf286625f61b604291f2eaed9702f0)
---
llvm/lib/MC/WasmObjectWriter.cpp | 89 ++++++++++++++-------------
llvm/test/MC/WebAssembly/init-array.s | 49 +++++++++++++++
2 files changed, 96 insertions(+), 42 deletions(-)
create mode 100644 llvm/test/MC/WebAssembly/init-array.s
diff --git a/llvm/lib/MC/WasmObjectWriter.cpp b/llvm/lib/MC/WasmObjectWriter.cpp
index f25dc92fa235a2..a66c5713ff8a6e 100644
--- a/llvm/lib/MC/WasmObjectWriter.cpp
+++ b/llvm/lib/MC/WasmObjectWriter.cpp
@@ -1853,49 +1853,54 @@ uint64_t WasmObjectWriter::writeOneObject(MCAssembler &Asm,
if (EmptyFrag.getKind() != MCFragment::FT_Data)
report_fatal_error(".init_array section should be aligned");
- const MCFragment &AlignFrag = *EmptyFrag.getNext();
- if (AlignFrag.getKind() != MCFragment::FT_Align)
- report_fatal_error(".init_array section should be aligned");
- if (cast<MCAlignFragment>(AlignFrag).getAlignment() !=
- Align(is64Bit() ? 8 : 4))
- report_fatal_error(".init_array section should be aligned for pointers");
-
- const MCFragment &Frag = *AlignFrag.getNext();
- if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data)
- report_fatal_error("only data supported in .init_array section");
-
- uint16_t Priority = UINT16_MAX;
- unsigned PrefixLength = strlen(".init_array");
- if (WS.getName().size() > PrefixLength) {
- if (WS.getName()[PrefixLength] != '.')
+ const MCFragment *nextFrag = EmptyFrag.getNext();
+ while (nextFrag != nullptr) {
+ const MCFragment &AlignFrag = *nextFrag;
+ if (AlignFrag.getKind() != MCFragment::FT_Align)
+ report_fatal_error(".init_array section should be aligned");
+ if (cast<MCAlignFragment>(AlignFrag).getAlignment() !=
+ Align(is64Bit() ? 8 : 4))
report_fatal_error(
- ".init_array section priority should start with '.'");
- if (WS.getName().substr(PrefixLength + 1).getAsInteger(10, Priority))
- report_fatal_error("invalid .init_array section priority");
- }
- const auto &DataFrag = cast<MCDataFragment>(Frag);
- const SmallVectorImpl<char> &Contents = DataFrag.getContents();
- for (const uint8_t *
- P = (const uint8_t *)Contents.data(),
- *End = (const uint8_t *)Contents.data() + Contents.size();
- P != End; ++P) {
- if (*P != 0)
- report_fatal_error("non-symbolic data in .init_array section");
- }
- for (const MCFixup &Fixup : DataFrag.getFixups()) {
- assert(Fixup.getKind() ==
- MCFixup::getKindForSize(is64Bit() ? 8 : 4, false));
- const MCExpr *Expr = Fixup.getValue();
- auto *SymRef = dyn_cast<MCSymbolRefExpr>(Expr);
- if (!SymRef)
- report_fatal_error("fixups in .init_array should be symbol references");
- const auto &TargetSym = cast<const MCSymbolWasm>(SymRef->getSymbol());
- if (TargetSym.getIndex() == InvalidIndex)
- report_fatal_error("symbols in .init_array should exist in symtab");
- if (!TargetSym.isFunction())
- report_fatal_error("symbols in .init_array should be for functions");
- InitFuncs.push_back(
- std::make_pair(Priority, TargetSym.getIndex()));
+ ".init_array section should be aligned for pointers");
+
+ const MCFragment &Frag = *AlignFrag.getNext();
+ nextFrag = Frag.getNext();
+ if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data)
+ report_fatal_error("only data supported in .init_array section");
+
+ uint16_t Priority = UINT16_MAX;
+ unsigned PrefixLength = strlen(".init_array");
+ if (WS.getName().size() > PrefixLength) {
+ if (WS.getName()[PrefixLength] != '.')
+ report_fatal_error(
+ ".init_array section priority should start with '.'");
+ if (WS.getName().substr(PrefixLength + 1).getAsInteger(10, Priority))
+ report_fatal_error("invalid .init_array section priority");
+ }
+ const auto &DataFrag = cast<MCDataFragment>(Frag);
+ const SmallVectorImpl<char> &Contents = DataFrag.getContents();
+ for (const uint8_t *
+ P = (const uint8_t *)Contents.data(),
+ *End = (const uint8_t *)Contents.data() + Contents.size();
+ P != End; ++P) {
+ if (*P != 0)
+ report_fatal_error("non-symbolic data in .init_array section");
+ }
+ for (const MCFixup &Fixup : DataFrag.getFixups()) {
+ assert(Fixup.getKind() ==
+ MCFixup::getKindForSize(is64Bit() ? 8 : 4, false));
+ const MCExpr *Expr = Fixup.getValue();
+ auto *SymRef = dyn_cast<MCSymbolRefExpr>(Expr);
+ if (!SymRef)
+ report_fatal_error(
+ "fixups in .init_array should be symbol references");
+ const auto &TargetSym = cast<const MCSymbolWasm>(SymRef->getSymbol());
+ if (TargetSym.getIndex() == InvalidIndex)
+ report_fatal_error("symbols in .init_array should exist in symtab");
+ if (!TargetSym.isFunction())
+ report_fatal_error("symbols in .init_array should be for functions");
+ InitFuncs.push_back(std::make_pair(Priority, TargetSym.getIndex()));
+ }
}
}
diff --git a/llvm/test/MC/WebAssembly/init-array.s b/llvm/test/MC/WebAssembly/init-array.s
new file mode 100644
index 00000000000000..e79fb453ec12a3
--- /dev/null
+++ b/llvm/test/MC/WebAssembly/init-array.s
@@ -0,0 +1,49 @@
+# RUN: llvm-mc -triple=wasm32-unknown-unknown -filetype=obj < %s | obj2yaml | FileCheck %s
+
+init1:
+ .functype init1 () -> ()
+ end_function
+
+init2:
+ .functype init2 () -> ()
+ end_function
+
+ .section .init_array,"",@
+ .p2align 2, 0
+ .int32 init1
+
+ .section .init_array,"",@
+ .p2align 2
+ .int32 init2
+
+# CHECK: - Type: FUNCTION
+# CHECK-NEXT: FunctionTypes: [ 0, 0 ]
+# CHECK-NEXT: - Type: CODE
+# CHECK-NEXT: Functions:
+# CHECK-NEXT: - Index: 0
+# CHECK-NEXT: Locals: []
+# CHECK-NEXT: Body: 0B
+# CHECK-NEXT: - Index: 1
+# CHECK-NEXT: Locals: []
+# CHECK-NEXT: Body: 0B
+# CHECK-NEXT: - Type: CUSTOM
+# CHECK-NEXT: Name: linking
+# CHECK-NEXT: Version: 2
+# CHECK-NEXT: SymbolTable:
+# CHECK-NEXT: - Index: 0
+# CHECK-NEXT: Kind: FUNCTION
+# CHECK-NEXT: Name: init1
+# CHECK-NEXT: Flags: [ BINDING_LOCAL ]
+# CHECK-NEXT: Function: 0
+# CHECK-NEXT: - Index: 1
+# CHECK-NEXT: Kind: FUNCTION
+# CHECK-NEXT: Name: init2
+# CHECK-NEXT: Flags: [ BINDING_LOCAL ]
+# CHECK-NEXT: Function: 1
+# CHECK-NEXT: InitFunctions:
+# CHECK-NEXT: - Priority: 65535
+# CHECK-NEXT: Symbol: 0
+# CHECK-NEXT: - Priority: 65535
+# CHECK-NEXT: Symbol: 1
+# CHECK-NEXT: ...
+#
>From 1040a263f0349a5d07ffff135ace6bbb21588ef1 Mon Sep 17 00:00:00 2001
From: George Stagg <george.stagg at posit.co>
Date: Tue, 10 Dec 2024 16:28:18 +0000
Subject: [PATCH 2/2] [WebAssembly] Handle symbols in `.init_array` sections
(#119127)
Follow on from #111008.
(cherry picked from commit ed91843d435d0cd2c39ebb1a50f2907c621f07ed)
---
llvm/lib/MC/WasmObjectWriter.cpp | 22 ++++-
llvm/test/MC/WebAssembly/init-array-label.s | 91 +++++++++++++++++++++
2 files changed, 111 insertions(+), 2 deletions(-)
create mode 100644 llvm/test/MC/WebAssembly/init-array-label.s
diff --git a/llvm/lib/MC/WasmObjectWriter.cpp b/llvm/lib/MC/WasmObjectWriter.cpp
index a66c5713ff8a6e..85264692456767 100644
--- a/llvm/lib/MC/WasmObjectWriter.cpp
+++ b/llvm/lib/MC/WasmObjectWriter.cpp
@@ -1326,6 +1326,22 @@ static bool isInSymtab(const MCSymbolWasm &Sym) {
return true;
}
+static bool isSectionReferenced(MCAssembler &Asm, MCSectionWasm &Section) {
+ StringRef SectionName = Section.getName();
+
+ for (const MCSymbol &S : Asm.symbols()) {
+ const auto &WS = static_cast<const MCSymbolWasm &>(S);
+ if (WS.isData() && WS.isInSection()) {
+ auto &RefSection = static_cast<MCSectionWasm &>(WS.getSection());
+ if (RefSection.getName() == SectionName) {
+ return true;
+ }
+ }
+ }
+
+ return false;
+}
+
void WasmObjectWriter::prepareImports(
SmallVectorImpl<wasm::WasmImport> &Imports, MCAssembler &Asm) {
// For now, always emit the memory import, since loads and stores are not
@@ -1482,8 +1498,10 @@ uint64_t WasmObjectWriter::writeOneObject(MCAssembler &Asm,
LLVM_DEBUG(dbgs() << "Processing Section " << SectionName << " group "
<< Section.getGroup() << "\n";);
- // .init_array sections are handled specially elsewhere.
- if (SectionName.starts_with(".init_array"))
+ // .init_array sections are handled specially elsewhere, include them in
+ // data segments if and only if referenced by a symbol.
+ if (SectionName.starts_with(".init_array") &&
+ !isSectionReferenced(Asm, Section))
continue;
// Code is handled separately
diff --git a/llvm/test/MC/WebAssembly/init-array-label.s b/llvm/test/MC/WebAssembly/init-array-label.s
new file mode 100644
index 00000000000000..0b4a5ea2da0b59
--- /dev/null
+++ b/llvm/test/MC/WebAssembly/init-array-label.s
@@ -0,0 +1,91 @@
+# RUN: llvm-mc -triple=wasm32-unknown-unknown -filetype=obj < %s | obj2yaml | FileCheck %s
+
+init1:
+ .functype init1 () -> ()
+ end_function
+
+init2:
+ .functype init2 () -> ()
+ end_function
+
+ .section .init_array.42,"",@
+ .p2align 2, 0x0
+ .int32 init1
+
+ .section .init_array,"",@
+ .globl p_init1
+ .p2align 2, 0x0
+p_init1:
+ .int32 init1
+ .size p_init1, 4
+
+ .section .init_array,"",@
+ .globl p_init2
+ .p2align 2, 0x0
+p_init2:
+ .int32 init1
+ .int32 init2
+ .size p_init2, 8
+
+# CHECK: - Type: FUNCTION
+# CHECK-NEXT: FunctionTypes: [ 0, 0 ]
+# CHECK-NEXT: - Type: DATACOUNT
+# CHECK-NEXT: Count: 1
+# CHECK-NEXT: - Type: CODE
+# CHECK-NEXT: Functions:
+# CHECK-NEXT: - Index: 0
+# CHECK-NEXT: Locals: []
+# CHECK-NEXT: Body: 0B
+# CHECK-NEXT: - Index: 1
+# CHECK-NEXT: Locals: []
+# CHECK-NEXT: Body: 0B
+# CHECK-NEXT: - Type: DATA
+# CHECK-NEXT: Segments:
+# CHECK-NEXT: - SectionOffset: 6
+# CHECK-NEXT: InitFlags: 0
+# CHECK-NEXT: Offset:
+# CHECK-NEXT: Opcode: I32_CONST
+# CHECK-NEXT: Value: 0
+# CHECK-NEXT: Content: '000000000000000000000000'
+# CHECK-NEXT: - Type: CUSTOM
+# CHECK-NEXT: Name: linking
+# CHECK-NEXT: Version: 2
+# CHECK-NEXT: SymbolTable:
+# CHECK-NEXT: - Index: 0
+# CHECK-NEXT: Kind: FUNCTION
+# CHECK-NEXT: Name: init1
+# CHECK-NEXT: Flags: [ BINDING_LOCAL ]
+# CHECK-NEXT: Function: 0
+# CHECK-NEXT: - Index: 1
+# CHECK-NEXT: Kind: FUNCTION
+# CHECK-NEXT: Name: init2
+# CHECK-NEXT: Flags: [ BINDING_LOCAL ]
+# CHECK-NEXT: Function: 1
+# CHECK-NEXT: - Index: 2
+# CHECK-NEXT: Kind: DATA
+# CHECK-NEXT: Name: p_init1
+# CHECK-NEXT: Flags: [ ]
+# CHECK-NEXT: Segment: 0
+# CHECK-NEXT: Size: 4
+# CHECK-NEXT: - Index: 3
+# CHECK-NEXT: Kind: DATA
+# CHECK-NEXT: Name: p_init2
+# CHECK-NEXT: Flags: [ ]
+# CHECK-NEXT: Segment: 0
+# CHECK-NEXT: Offset: 4
+# CHECK-NEXT: Size: 8
+# CHECK-NEXT: SegmentInfo:
+# CHECK-NEXT: - Index: 0
+# CHECK-NEXT: Name: .init_array
+# CHECK-NEXT: Alignment: 2
+# CHECK-NEXT: Flags: [ ]
+# CHECK-NEXT: InitFunctions:
+# CHECK-NEXT: - Priority: 42
+# CHECK-NEXT: Symbol: 0
+# CHECK-NEXT: - Priority: 65535
+# CHECK-NEXT: Symbol: 0
+# CHECK-NEXT: - Priority: 65535
+# CHECK-NEXT: Symbol: 0
+# CHECK-NEXT: - Priority: 65535
+# CHECK-NEXT: Symbol: 1
+# CHECK-NEXT: ...
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