[llvm] 4324937 - [X86] Use "l" prefix for data sections under medium/large code model
Arthur Eubanks via llvm-commits
llvm-commits at lists.llvm.org
Wed May 31 12:31:20 PDT 2023
Author: Arthur Eubanks
Date: 2023-05-31T12:31:08-07:00
New Revision: 43249378da67319906cf04f2c6cd38df141f3bf6
URL: https://github.com/llvm/llvm-project/commit/43249378da67319906cf04f2c6cd38df141f3bf6
DIFF: https://github.com/llvm/llvm-project/commit/43249378da67319906cf04f2c6cd38df141f3bf6.diff
LOG: [X86] Use "l" prefix for data sections under medium/large code model
And also set the SHF_X86_64_LARGE section flag.
gcc only uses the "l" prefix and SHF_X86_64_LARGE in the medium code model for data larger than -mlarge-data-threshold. But it seems more consistent to use it in the large code model as well in case separate parts of the binary aren't compiled with the large code model and also have a .data/.bss/.rodata section.
Reviewed By: MaskRay, tkoeppe
Differential Revision: https://reviews.llvm.org/D148836
Added:
llvm/test/CodeGen/X86/code-model-elf-sections.ll
Modified:
llvm/include/llvm/Target/TargetMachine.h
llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
llvm/lib/Target/TargetMachine.cpp
Removed:
################################################################################
diff --git a/llvm/include/llvm/Target/TargetMachine.h b/llvm/include/llvm/Target/TargetMachine.h
index 31ec2ed93664f..0df1875cc395b 100644
--- a/llvm/include/llvm/Target/TargetMachine.h
+++ b/llvm/include/llvm/Target/TargetMachine.h
@@ -235,6 +235,8 @@ class TargetMachine {
/// Set the code model.
void setCodeModel(CodeModel::Model CM) { CMModel = CM; }
+ bool isLargeData() const;
+
bool isPositionIndependent() const;
bool shouldAssumeDSOLocal(const Module &M, const GlobalValue *GV) const;
diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index db1a4369e1291..9e0914f667f02 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -614,21 +614,21 @@ static unsigned getEntrySizeForKind(SectionKind Kind) {
/// Return the section prefix name used by options FunctionsSections and
/// DataSections.
-static StringRef getSectionPrefixForGlobal(SectionKind Kind) {
+static StringRef getSectionPrefixForGlobal(SectionKind Kind, bool IsLarge) {
if (Kind.isText())
return ".text";
if (Kind.isReadOnly())
- return ".rodata";
+ return IsLarge ? ".lrodata" : ".rodata";
if (Kind.isBSS())
- return ".bss";
+ return IsLarge ? ".lbss" : ".bss";
if (Kind.isThreadData())
return ".tdata";
if (Kind.isThreadBSS())
return ".tbss";
if (Kind.isData())
- return ".data";
+ return IsLarge ? ".ldata" : ".data";
if (Kind.isReadOnlyWithRel())
- return ".data.rel.ro";
+ return IsLarge ? ".ldata.rel.ro" : ".data.rel.ro";
llvm_unreachable("Unknown section kind");
}
@@ -650,7 +650,10 @@ getELFSectionNameForGlobal(const GlobalObject *GO, SectionKind Kind,
Name = ".rodata.cst";
Name += utostr(EntrySize);
} else {
- Name = getSectionPrefixForGlobal(Kind);
+ bool IsLarge = false;
+ if (isa<GlobalVariable>(GO))
+ IsLarge = TM.isLargeData();
+ Name = getSectionPrefixForGlobal(Kind, IsLarge);
}
bool HasPrefix = false;
@@ -852,6 +855,12 @@ static MCSectionELF *selectELFSectionForGlobal(
Group = C->getName();
IsComdat = C->getSelectionKind() == Comdat::Any;
}
+ if (isa<GlobalVariable>(GO)) {
+ if (TM.isLargeData()) {
+ assert(TM.getTargetTriple().getArch() == Triple::x86_64);
+ Flags |= ELF::SHF_X86_64_LARGE;
+ }
+ }
// Get the section entry size based on the kind.
unsigned EntrySize = getEntrySizeForKind(Kind);
@@ -2165,7 +2174,7 @@ static MCSectionWasm *selectWasmSectionForGlobal(
}
bool UniqueSectionNames = TM.getUniqueSectionNames();
- SmallString<128> Name = getSectionPrefixForGlobal(Kind);
+ SmallString<128> Name = getSectionPrefixForGlobal(Kind, /*IsLarge=*/false);
if (const auto *F = dyn_cast<Function>(GO)) {
const auto &OptionalPrefix = F->getSectionPrefix();
diff --git a/llvm/lib/Target/TargetMachine.cpp b/llvm/lib/Target/TargetMachine.cpp
index 2fbd1401da8ce..bc465168f1dba 100644
--- a/llvm/lib/Target/TargetMachine.cpp
+++ b/llvm/lib/Target/TargetMachine.cpp
@@ -21,6 +21,7 @@
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSubtargetInfo.h"
+#include "llvm/Support/CodeGen.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
using namespace llvm;
@@ -38,6 +39,16 @@ TargetMachine::TargetMachine(const Target &T, StringRef DataLayoutString,
TargetMachine::~TargetMachine() = default;
+bool TargetMachine::isLargeData() const {
+ if (getTargetTriple().getArch() != Triple::x86_64)
+ return false;
+ // Large data under the large code model still needs to be thought about, so
+ // restrict this to medium.
+ if (getCodeModel() != CodeModel::Medium)
+ return false;
+ return true;
+}
+
bool TargetMachine::isPositionIndependent() const {
return getRelocationModel() == Reloc::PIC_;
}
diff --git a/llvm/test/CodeGen/X86/code-model-elf-sections.ll b/llvm/test/CodeGen/X86/code-model-elf-sections.ll
new file mode 100644
index 0000000000000..24c672d10e95a
--- /dev/null
+++ b/llvm/test/CodeGen/X86/code-model-elf-sections.ll
@@ -0,0 +1,43 @@
+; RUN: llc < %s -relocation-model=pic -filetype=obj -code-model=small -o %t
+; RUN: llvm-readelf -S %t | FileCheck %s --check-prefix=SMALL
+; RUN: llc < %s -relocation-model=pic -filetype=obj -code-model=medium -o %t
+; RUN: llvm-readelf -S %t | FileCheck %s --check-prefix=LARGE
+; RUN: llc < %s -relocation-model=pic -filetype=obj -code-model=large -o %t
+; RUN: llvm-readelf -S %t | FileCheck %s --check-prefix=SMALL
+
+; RUN: llc < %s -relocation-model=pic -filetype=obj -code-model=small -data-sections -o %t
+; RUN: llvm-readelf -S %t | FileCheck %s --check-prefix=SMALL-DS
+; RUN: llc < %s -relocation-model=pic -filetype=obj -code-model=medium -data-sections -o %t
+; RUN: llvm-readelf -S %t | FileCheck %s --check-prefix=LARGE-DS
+; RUN: llc < %s -relocation-model=pic -filetype=obj -code-model=large -data-sections -o %t
+; RUN: llvm-readelf -S %t | FileCheck %s --check-prefix=SMALL-DS
+
+; SMALL: .data {{.*}} WA {{.*}}
+; SMALL: .bss {{.*}} WA {{.*}}
+; SMALL: .rodata {{.*}} A {{.*}}
+; SMALL: .data.rel.ro {{.*}} WA {{.*}}
+
+; SMALL-DS: .data.data {{.*}} WA {{.*}}
+; SMALL-DS: .bss.bss {{.*}} WA {{.*}}
+; SMALL-DS: .rodata.rodata {{.*}} A {{.*}}
+; SMALL-DS: .data.rel.ro.relro {{.*}} WA {{.*}}
+
+; LARGE: .ldata {{.*}} WAl {{.*}}
+; LARGE: .lbss {{.*}} WAl {{.*}}
+; LARGE: .lrodata {{.*}} Al {{.*}}
+; LARGE: .ldata.rel.ro {{.*}} WAl {{.*}}
+
+; LARGE-DS: .ldata.data {{.*}} WAl {{.*}}
+; LARGE-DS: .lbss.bss {{.*}} WAl {{.*}}
+; LARGE-DS: .lrodata.rodata {{.*}} Al {{.*}}
+; LARGE-DS: .ldata.rel.ro.relro {{.*}} WAl {{.*}}
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux"
+
+ at data = internal global [10 x i64] [i64 1, i64 2, i64 0, i64 0, i64 0, i64 0, i64 0, i64 0, i64 0, i64 0]
+ at bss = internal global [10 x i64] zeroinitializer
+ at rodata = internal constant [10 x i64] zeroinitializer
+ at relro = internal constant [10 x ptr] [ptr @func, ptr @func, ptr @func, ptr @func, ptr @func, ptr @func, ptr @func, ptr @func, ptr @func, ptr @func]
+
+declare void @func()
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