[RISCV] Let -data-sections also work on sbss/sdata sections #87040
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…sections Copied from sdata-limit-8.ll and update the CHECKs, otherwise it matches any .sbss/.sdata regardless having a suffix or not.
Without assigning an unique .sbss/.sdata section to each symbols, a linker may not be able to remove unused part when gc-section since all used and unused symbols are all mixed in the same .sbss/.sdata section. I believe this also matches the behavior of gcc.
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@llvm/pr-subscribers-backend-risc-v Author: KaiWeng (KaiYG) ChangesAdd an unique suffix to .sbss/.sdata if -fdata-sections. Full diff: https://github.com/llvm/llvm-project/pull/87040.diff 2 Files Affected:
diff --git a/llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp b/llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp
index e7c1a7e5d8bca1..b13df905249ab5 100644
--- a/llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp
+++ b/llvm/lib/Target/RISCV/RISCVTargetObjectFile.cpp
@@ -104,10 +104,36 @@ bool RISCVELFTargetObjectFile::isGlobalInSmallSection(
MCSection *RISCVELFTargetObjectFile::SelectSectionForGlobal(
const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
// Handle Small Section classification here.
- if (Kind.isBSS() && isGlobalInSmallSection(GO, TM))
- return SmallBSSSection;
- if (Kind.isData() && isGlobalInSmallSection(GO, TM))
- return SmallDataSection;
+ if (isGlobalInSmallSection(GO, TM)) {
+ // Emit a unique section for sdata/sbss when -fdata-section.
+ bool EmitUniquedSection = TM.getDataSections();
+
+ if (Kind.isBSS()) {
+ if (EmitUniquedSection) {
+ StringRef Prefix(".sbss");
+ SmallString<128> Name(Prefix);
+ Name.append(".");
+ Name.append(GO->getName());
+ return getContext().getELFSection(Name.str(), ELF::SHT_NOBITS,
+ ELF::SHF_WRITE | ELF::SHF_ALLOC);
+ }
+
+ return SmallBSSSection;
+ }
+
+ if (Kind.isData()) {
+ if (EmitUniquedSection) {
+ StringRef Prefix(".sdata");
+ SmallString<128> Name(Prefix);
+ Name.append(".");
+ Name.append(GO->getName());
+ return getContext().getELFSection(Name.str(), ELF::SHT_PROGBITS,
+ ELF::SHF_WRITE | ELF::SHF_ALLOC);
+ }
+
+ return SmallDataSection;
+ }
+ }
// Otherwise, we work the same as ELF.
return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
diff --git a/llvm/test/CodeGen/RISCV/sdata-sections.ll b/llvm/test/CodeGen/RISCV/sdata-sections.ll
new file mode 100644
index 00000000000000..175e6d744843a8
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/sdata-sections.ll
@@ -0,0 +1,17 @@
+; RUN: llc -mtriple=riscv32 -data-sections < %s | FileCheck -check-prefix=RV32 %s
+; RUN: llc -mtriple=riscv64 -data-sections < %s | FileCheck -check-prefix=RV64 %s
+
+; Append an unique name to each sdata/sbss section when -data-section.
+
+@v = dso_local global i32 0, align 4
+@r = dso_local global i64 7, align 8
+
+; SmallDataLimit set to 8, so we expect @v will be put in sbss
+; and @r will be put in sdata.
+!llvm.module.flags = !{!0}
+!0 = !{i32 8, !"SmallDataLimit", i32 8}
+
+; RV32: .section .sbss.v,"aw"
+; RV32: .section .sdata.r,"aw"
+; RV64: .section .sbss.v,"aw"
+; RV64: .section .sdata.r,"aw"
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Ping. |
Add an unique suffix to .sbss/.sdata if -fdata-sections.
Without assigning an unique .sbss/.sdata section to each symbols, a linker may not be able to remove unused part when gc-section since all used and unused symbols are all mixed in the same .sbss/.sdata section.
I believe this also matches the behavior of gcc.