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[RISCV] Place mergeable small read only data into srodata section #82214

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Mar 11, 2024
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[RISCV] Place mergeable small read only data into srodata section #82214

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c764701
[RISCV] Place mergeable small read only data into srodata section
kito-cheng Feb 16, 2024
5856afe
!fixup: drop unnecessary else
kito-cheng Feb 19, 2024
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25 changes: 23 additions & 2 deletions llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,16 @@ void RISCVELFTargetObjectFile::Initialize(MCContext &Ctx,
".sdata", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
SmallBSSSection = getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
ELF::SHF_WRITE | ELF::SHF_ALLOC);
SmallRODataSection =
getContext().getELFSection(".srodata", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
SmallROData4Section = getContext().getELFSection(
".srodata.cst4", ELF::SHT_PROGBITS, ELF::SHF_ALLOC | ELF::SHF_MERGE, 4);
SmallROData8Section = getContext().getELFSection(
".srodata.cst8", ELF::SHT_PROGBITS, ELF::SHF_ALLOC | ELF::SHF_MERGE, 8);
SmallROData16Section = getContext().getELFSection(
".srodata.cst16", ELF::SHT_PROGBITS, ELF::SHF_ALLOC | ELF::SHF_MERGE, 16);
SmallROData32Section = getContext().getELFSection(
".srodata.cst32", ELF::SHT_PROGBITS, ELF::SHF_ALLOC | ELF::SHF_MERGE, 32);
}

const MCExpr *RISCVELFTargetObjectFile::getIndirectSymViaGOTPCRel(
Expand Down Expand Up @@ -126,8 +136,19 @@ bool RISCVELFTargetObjectFile::isConstantInSmallSection(
MCSection *RISCVELFTargetObjectFile::getSectionForConstant(
const DataLayout &DL, SectionKind Kind, const Constant *C,
Align &Alignment) const {
if (isConstantInSmallSection(DL, C))
return SmallDataSection;
if (isConstantInSmallSection(DL, C)) {
if (Kind.isMergeableConst4())
return SmallROData4Section;
if (Kind.isMergeableConst8())
return SmallROData8Section;
if (Kind.isMergeableConst16())
return SmallROData16Section;
if (Kind.isMergeableConst32())
return SmallROData32Section;
// LLVM only generate up to .rodata.cst32, and use .rodata section if more
// than 32 bytes, so just use .srodata here.
return SmallRODataSection;
}

// Otherwise, we work the same as ELF.
return TargetLoweringObjectFileELF::getSectionForConstant(DL, Kind, C,
Expand Down
5 changes: 5 additions & 0 deletions llvm/lib/Target/RISCV/RISCVTargetObjectFile.h
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Expand Up @@ -16,6 +16,11 @@ namespace llvm {
/// This implementation is used for RISC-V ELF targets.
class RISCVELFTargetObjectFile : public TargetLoweringObjectFileELF {
MCSection *SmallDataSection;
MCSection *SmallRODataSection;
MCSection *SmallROData4Section;
MCSection *SmallROData8Section;
MCSection *SmallROData16Section;
MCSection *SmallROData32Section;
MCSection *SmallBSSSection;
unsigned SSThreshold = 8;

Expand Down
47 changes: 47 additions & 0 deletions llvm/test/CodeGen/RISCV/srodata.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,47 @@
; RUN: sed 's/SMALL_DATA_LIMIT/0/g' %s | \
; RUN: llc -mtriple=riscv32 -mattr=+d | \
; RUN: FileCheck -check-prefix=CHECK-SDL-0 %s
; RUN: sed 's/SMALL_DATA_LIMIT/0/g' %s | \
; RUN: llc -mtriple=riscv64 -mattr=+d | \
; RUN: FileCheck -check-prefix=CHECK-SDL-0 %s
; RUN: sed 's/SMALL_DATA_LIMIT/4/g' %s | \
; RUN: llc -mtriple=riscv32 -mattr=+d | \
; RUN: FileCheck -check-prefix=CHECK-SDL-4 %s
; RUN: sed 's/SMALL_DATA_LIMIT/4/g' %s | \
; RUN: llc -mtriple=riscv64 -mattr=+d | \
; RUN: FileCheck -check-prefix=CHECK-SDL-4 %s
; RUN: sed 's/SMALL_DATA_LIMIT/8/g' %s | \
; RUN: llc -mtriple=riscv32 -mattr=+d | \
; RUN: FileCheck -check-prefix=CHECK-SDL-8 %s
; RUN: sed 's/SMALL_DATA_LIMIT/8/g' %s | \
; RUN: llc -mtriple=riscv64 -mattr=+d | \
; RUN: FileCheck -check-prefix=CHECK-SDL-8 %s
; RUN: sed 's/SMALL_DATA_LIMIT/16/g' %s | \
; RUN: llc -mtriple=riscv32 -mattr=+d | \
; RUN: FileCheck -check-prefix=CHECK-SDL-16 %s
; RUN: sed 's/SMALL_DATA_LIMIT/16/g' %s | \
; RUN: llc -mtriple=riscv64 -mattr=+d | \
; RUN: FileCheck -check-prefix=CHECK-SDL-16 %s

define dso_local float @foof() {
entry:
ret float 0x400A08ACA0000000
}

define dso_local double @foo() {
entry:
ret double 0x400A08AC91C3E242
}

!llvm.module.flags = !{!0}

!0 = !{i32 8, !"SmallDataLimit", i32 SMALL_DATA_LIMIT}

; CHECK-SDL-0-NOT: .section .srodata.cst4
; CHECK-SDL-0-NOT: .section .srodata.cst8
; CHECK-SDL-4: .section .srodata.cst4
; CHECK-SDL-4-NOT: .section .srodata.cst8
; CHECK-SDL-8: .section .srodata.cst4
; CHECK-SDL-8: .section .srodata.cst8
; CHECK-SDL-16: .section .srodata.cst4
; CHECK-SDL-16: .section .srodata.cst8
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