[llvm] [LoongArch] Add relax feature and keep relocations (PR #72191)
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Mon Nov 13 18:06:25 PST 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-loongarch
Author: Jinyang He (MQ-mengqing)
<details>
<summary>Changes</summary>
Add relax feature. To support linker relocation, we should make relocation with a symbol rather than section plus offset, and keep all relocations with non-abs symbol.
---
Full diff: https://github.com/llvm/llvm-project/pull/72191.diff
6 Files Affected:
- (modified) llvm/lib/Target/LoongArch/LoongArch.td (+4)
- (modified) llvm/lib/Target/LoongArch/LoongArchSubtarget.h (+2)
- (modified) llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchAsmBackend.cpp (+3-2)
- (modified) llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchELFObjectWriter.cpp (+13-5)
- (modified) llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMCTargetDesc.h (+1-1)
- (added) llvm/test/MC/LoongArch/Relocations/relax-attr.s (+32)
``````````diff
diff --git a/llvm/lib/Target/LoongArch/LoongArch.td b/llvm/lib/Target/LoongArch/LoongArch.td
index 0675caa3b60145d..75b65fe69f26291 100644
--- a/llvm/lib/Target/LoongArch/LoongArch.td
+++ b/llvm/lib/Target/LoongArch/LoongArch.td
@@ -102,6 +102,10 @@ def FeatureUAL
: SubtargetFeature<"ual", "HasUAL", "true",
"Allow memory accesses to be unaligned">;
+def FeatureRelax
+ : SubtargetFeature<"relax", "HasLinkerRelax", "true",
+ "Enable Linker relaxation">;
+
//===----------------------------------------------------------------------===//
// Registers, instruction descriptions ...
//===----------------------------------------------------------------------===//
diff --git a/llvm/lib/Target/LoongArch/LoongArchSubtarget.h b/llvm/lib/Target/LoongArch/LoongArchSubtarget.h
index 0fbe23f2f62d9d4..5c173675cca4ccb 100644
--- a/llvm/lib/Target/LoongArch/LoongArchSubtarget.h
+++ b/llvm/lib/Target/LoongArch/LoongArchSubtarget.h
@@ -43,6 +43,7 @@ class LoongArchSubtarget : public LoongArchGenSubtargetInfo {
bool HasLaGlobalWithAbs = false;
bool HasLaLocalWithAbs = false;
bool HasUAL = false;
+ bool HasLinkerRelax = false;
unsigned GRLen = 32;
MVT GRLenVT = MVT::i32;
LoongArchABI::ABI TargetABI = LoongArchABI::ABI_Unknown;
@@ -100,6 +101,7 @@ class LoongArchSubtarget : public LoongArchGenSubtargetInfo {
bool hasLaGlobalWithAbs() const { return HasLaGlobalWithAbs; }
bool hasLaLocalWithAbs() const { return HasLaLocalWithAbs; }
bool hasUAL() const { return HasUAL; }
+ bool hasLinkerRelax() const { return HasLinkerRelax; }
MVT getGRLenVT() const { return GRLenVT; }
unsigned getGRLen() const { return GRLen; }
LoongArchABI::ABI getTargetABI() const { return TargetABI; }
diff --git a/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchAsmBackend.cpp b/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchAsmBackend.cpp
index 8744bcb45f75f30..a35916d2ad2197d 100644
--- a/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchAsmBackend.cpp
+++ b/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchAsmBackend.cpp
@@ -167,7 +167,7 @@ bool LoongArchAsmBackend::shouldForceRelocation(const MCAssembler &Asm,
return true;
switch (Fixup.getTargetKind()) {
default:
- return false;
+ return STI.hasFeature(LoongArch::FeatureRelax);
case FK_Data_1:
case FK_Data_2:
case FK_Data_4:
@@ -192,7 +192,8 @@ bool LoongArchAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count,
std::unique_ptr<MCObjectTargetWriter>
LoongArchAsmBackend::createObjectTargetWriter() const {
- return createLoongArchELFObjectWriter(OSABI, Is64Bit);
+ return createLoongArchELFObjectWriter(
+ OSABI, Is64Bit, STI.hasFeature(LoongArch::FeatureRelax));
}
MCAsmBackend *llvm::createLoongArchAsmBackend(const Target &T,
diff --git a/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchELFObjectWriter.cpp b/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchELFObjectWriter.cpp
index a6b9c0652639fbc..8a464b894265146 100644
--- a/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchELFObjectWriter.cpp
+++ b/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchELFObjectWriter.cpp
@@ -20,19 +20,27 @@ using namespace llvm;
namespace {
class LoongArchELFObjectWriter : public MCELFObjectTargetWriter {
public:
- LoongArchELFObjectWriter(uint8_t OSABI, bool Is64Bit);
+ LoongArchELFObjectWriter(uint8_t OSABI, bool Is64Bit, bool EnableRelax);
~LoongArchELFObjectWriter() override;
+ bool needsRelocateWithSymbol(const MCValue &Val, const MCSymbol &Sym,
+ unsigned Type) const override {
+ return EnableRelax;
+ }
+
protected:
unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
const MCFixup &Fixup, bool IsPCRel) const override;
+ bool EnableRelax;
};
} // end namespace
-LoongArchELFObjectWriter::LoongArchELFObjectWriter(uint8_t OSABI, bool Is64Bit)
+LoongArchELFObjectWriter::LoongArchELFObjectWriter(uint8_t OSABI, bool Is64Bit,
+ bool EnableRelax)
: MCELFObjectTargetWriter(Is64Bit, OSABI, ELF::EM_LOONGARCH,
- /*HasRelocationAddend*/ true) {}
+ /*HasRelocationAddend*/ true),
+ EnableRelax(EnableRelax) {}
LoongArchELFObjectWriter::~LoongArchELFObjectWriter() {}
@@ -87,6 +95,6 @@ unsigned LoongArchELFObjectWriter::getRelocType(MCContext &Ctx,
}
std::unique_ptr<MCObjectTargetWriter>
-llvm::createLoongArchELFObjectWriter(uint8_t OSABI, bool Is64Bit) {
- return std::make_unique<LoongArchELFObjectWriter>(OSABI, Is64Bit);
+llvm::createLoongArchELFObjectWriter(uint8_t OSABI, bool Is64Bit, bool Relax) {
+ return std::make_unique<LoongArchELFObjectWriter>(OSABI, Is64Bit, Relax);
}
diff --git a/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMCTargetDesc.h b/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMCTargetDesc.h
index ab35a0096c8a2a2..bb05baa9b717c2c 100644
--- a/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMCTargetDesc.h
+++ b/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMCTargetDesc.h
@@ -36,7 +36,7 @@ MCAsmBackend *createLoongArchAsmBackend(const Target &T,
const MCTargetOptions &Options);
std::unique_ptr<MCObjectTargetWriter>
-createLoongArchELFObjectWriter(uint8_t OSABI, bool Is64Bit);
+createLoongArchELFObjectWriter(uint8_t OSABI, bool Is64Bit, bool Relax);
} // end namespace llvm
diff --git a/llvm/test/MC/LoongArch/Relocations/relax-attr.s b/llvm/test/MC/LoongArch/Relocations/relax-attr.s
new file mode 100644
index 000000000000000..b1e648d850bb908
--- /dev/null
+++ b/llvm/test/MC/LoongArch/Relocations/relax-attr.s
@@ -0,0 +1,32 @@
+# RUN: llvm-mc --filetype=obj --triple=loongarch64 %s -o %t
+# RUN: llvm-readobj -r %t | FileCheck %s
+# RUN: llvm-mc --filetype=obj --triple=loongarch64 -mattr=+relax %s -o %t
+# RUN: llvm-readobj -r %t | FileCheck %s --check-prefix=CHECKR
+
+# CHECK: Relocations [
+# CHECK-NEXT: Section ({{.*}}) .rela.data {
+# CHECK-NEXT: 0x0 R_LARCH_64 .text 0x4
+# CHECK-NEXT: }
+# CHECK-NEXT: ]
+
+# CHECKR: Relocations [
+# CHECKR-NEXT: Section ({{.*}}) .rela.text {
+# CHECKR-NEXT: 0x8 R_LARCH_B21 .L1 0x0
+# CHECKR-NEXT: 0xC R_LARCH_B16 .L1 0x0
+# CHECKR-NEXT: 0x10 R_LARCH_B26 .L1 0x0
+# CHECKR-NEXT: }
+# CHECKR-NEXT: Section ({{.*}}) .rela.data {
+# CHECKR-NEXT: 0x0 R_LARCH_64 .L1 0x0
+# CHECKR-NEXT: }
+# CHECKR-NEXT: ]
+
+.text
+ nop
+.L1:
+ nop
+ beqz $a0, .L1
+ blt $a0, $a1, .L1
+ b .L1
+
+.data
+.dword .L1
``````````
</details>
https://github.com/llvm/llvm-project/pull/72191
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