[lld] [llvm] Reapply "[RISCV] Support RISCV Atomics ABI attributes (#84597)" (PR #90266)

Paul Kirth via llvm-commits llvm-commits at lists.llvm.org
Mon Jul 1 13:59:36 PDT 2024


https://github.com/ilovepi updated https://github.com/llvm/llvm-project/pull/90266

>From d5fbe29b7981fa654ee47d2020c1c2ca2e619680 Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulkirth at google.com>
Date: Fri, 26 Apr 2024 13:51:21 -0700
Subject: [PATCH 1/8] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20in?=
 =?UTF-8?q?itial=20version?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Created using spr 1.3.4
---
 lld/ELF/Arch/RISCV.cpp                        |  63 ++++++
 lld/test/ELF/riscv-attributes.s               | 202 ++++++++++++++++++
 .../llvm/Support/RISCVAttributeParser.h       |   1 +
 llvm/include/llvm/Support/RISCVAttributes.h   |  13 ++
 llvm/lib/Support/RISCVAttributeParser.cpp     |  13 +-
 llvm/lib/Support/RISCVAttributes.cpp          |   1 +
 .../MCTargetDesc/RISCVTargetStreamer.cpp      |   7 +
 llvm/test/CodeGen/RISCV/attributes.ll         |  10 +-
 llvm/test/MC/RISCV/attribute.s                |   3 +
 llvm/test/MC/RISCV/invalid-attribute.s        |   3 +
 10 files changed, 314 insertions(+), 2 deletions(-)

diff --git a/lld/ELF/Arch/RISCV.cpp b/lld/ELF/Arch/RISCV.cpp
index 20088d92bafa2..7b9c9c6c6c385 100644
--- a/lld/ELF/Arch/RISCV.cpp
+++ b/lld/ELF/Arch/RISCV.cpp
@@ -1084,10 +1084,62 @@ static void mergeArch(RISCVISAInfo::OrderedExtensionMap &mergedExts,
   }
 }
 
+static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
+                        const InputSectionBase *oldSection,
+                        const InputSectionBase *newSection, unsigned int oldTag,
+                        unsigned int newTag) {
+  using RISCVAttrs::RISCVAtomicAbiTag::AtomicABI;
+  // Same tags stay the same, and UNKNOWN is compatible with anything
+  if (oldTag == newTag || newTag == AtomicABI::UNKNOWN)
+    return;
+
+  switch (oldTag) {
+  case AtomicABI::UNKNOWN:
+    it->getSecond() = newTag;
+    return;
+  case AtomicABI::A6C:
+    switch (newTag) {
+    case AtomicABI::A6S:
+      it->getSecond() = AtomicABI::A6C;
+      return;
+    case AtomicABI::A7:
+      error(toString(oldSection) + " has atomic_abi=" + Twine(oldTag) +
+            " but " + toString(newSection) +
+            " has atomic_abi=" + Twine(newTag));
+      return;
+    };
+
+  case AtomicABI::A6S:
+    switch (newTag) {
+    case AtomicABI::A6C:
+      it->getSecond() = AtomicABI::A6C;
+      return;
+    case AtomicABI::A7:
+      it->getSecond() = AtomicABI::A7;
+      return;
+    };
+
+  case AtomicABI::A7:
+    switch (newTag) {
+    case AtomicABI::A6S:
+      it->getSecond() = AtomicABI::A7;
+      return;
+    case AtomicABI::A6C:
+      error(toString(oldSection) + " has atomic_abi=" + Twine(oldTag) +
+            " but " + toString(newSection) +
+            " has atomic_abi=" + Twine(newTag));
+      return;
+    };
+  default:
+    llvm_unreachable("unknown AtomicABI");
+  };
+}
+
 static RISCVAttributesSection *
 mergeAttributesSection(const SmallVector<InputSectionBase *, 0> &sections) {
   RISCVISAInfo::OrderedExtensionMap exts;
   const InputSectionBase *firstStackAlign = nullptr;
+  const InputSectionBase *firstAtomicAbi = nullptr;
   unsigned firstStackAlignValue = 0, xlen = 0;
   bool hasArch = false;
 
@@ -1134,6 +1186,17 @@ mergeAttributesSection(const SmallVector<InputSectionBase *, 0> &sections) {
       case RISCVAttrs::PRIV_SPEC_MINOR:
       case RISCVAttrs::PRIV_SPEC_REVISION:
         break;
+
+      case llvm::RISCVAttrs::AttrType::ATOMIC_ABI:
+        if (auto i = parser.getAttributeValue(tag.attr)) {
+          auto r = merged.intAttr.try_emplace(tag.attr, *i);
+          if (r.second) {
+            firstAtomicAbi = sec;
+          } else {
+            mergeAtomic(r.first, firstAtomicAbi, sec, r.first->getSecond(), *i);
+          }
+        }
+        continue;
       }
 
       // Fallback for deprecated priv_spec* and other unknown attributes: retain
diff --git a/lld/test/ELF/riscv-attributes.s b/lld/test/ELF/riscv-attributes.s
index d0ce0941269ec..77c2c3cb263fd 100644
--- a/lld/test/ELF/riscv-attributes.s
+++ b/lld/test/ELF/riscv-attributes.s
@@ -44,6 +44,39 @@
 # RUN: not ld.lld a.o b.o c.o diff_stack_align.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=STACK_ALIGN --implicit-check-not=error:
 # STACK_ALIGN: error: diff_stack_align.o:(.riscv.attributes) has stack_align=32 but a.o:(.riscv.attributes) has stack_align=16
 
+## merging atomic_abi values for A6C and A7 lead to an error.
+# RUN: llvm-mc -filetype=obj -triple=riscv64  atomic_abi_A6C.s -o atomic_abi_A6C.o
+# RUN: llvm-mc -filetype=obj -triple=riscv64  atomic_abi_A7.s -o atomic_abi_A7.o
+# RUN: not ld.lld atomic_abi_A6C.o atomic_abi_A7.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=ATOMIC_ABI_ERROR --implicit-check-not=error:
+# ATOMIC_ABI_ERROR: error: atomic_abi_A6C.o:(.riscv.attributes) has atomic_abi=1 but atomic_abi_A7.o:(.riscv.attributes) has atomic_abi=3
+
+
+# RUN: llvm-mc -filetype=obj -triple=riscv64  atomic_abi_A6S.s -o atomic_abi_A6S.o
+# RUN: ld.lld atomic_abi_A6S.o atomic_abi_A6C.o -o atomic_abi_A6C_A6S
+# RUN: llvm-readobj -A atomic_abi_A6C_A6S | FileCheck %s --check-prefix=A6C_A6S
+
+# RUN: ld.lld atomic_abi_A6S.o atomic_abi_A7.o -o atomic_abi_A6S_A7
+# RUN: llvm-readobj -A atomic_abi_A6S_A7 | FileCheck %s --check-prefix=A6S_A7
+
+# RUN: llvm-mc -filetype=obj -triple=riscv64  atomic_abi_unknown.s -o atomic_abi_unknown.o
+# RUN: ld.lld atomic_abi_unknown.o atomic_abi_A6C.o -o atomic_abi_A6C_unknown
+# RUN: llvm-readobj -A atomic_abi_A6C_unknown | FileCheck %s --check-prefixes=UNKNOWN_A6C
+
+# RUN: ld.lld atomic_abi_unknown.o diff_stack_align.o -o atomic_abi_none_unknown
+# RUN: llvm-readobj -A atomic_abi_none_unknown | FileCheck %s --check-prefixes=UNKNOWN_NONE
+
+# RUN: ld.lld diff_stack_align.o atomic_abi_A6C.o -o atomic_abi_A6C_none
+# RUN: llvm-readobj -A atomic_abi_A6C_none | FileCheck %s --check-prefixes=NONE_A6C
+
+# RUN: ld.lld atomic_abi_unknown.o atomic_abi_A6S.o -o atomic_abi_A6S_unknown
+# RUN: llvm-readobj -A atomic_abi_A6S_unknown | FileCheck %s --check-prefix=UNKNOWN_A6S
+
+# RUN: ld.lld atomic_abi_unknown.o atomic_abi_A7.o -o atomic_abi_A7_unknown
+# RUN: llvm-readobj -A atomic_abi_A7_unknown | FileCheck %s --check-prefix=UNKNOWN_A7
+
+# RUN: ld.lld diff_stack_align.o atomic_abi_A7.o -o atomic_abi_A7_none
+# RUN: llvm-readobj -A atomic_abi_A7_none | FileCheck %s --check-prefix=NONE_A7
+
 ## The deprecated priv_spec is not handled as GNU ld does.
 ## Differing priv_spec attributes lead to an absent attribute.
 # RUN: llvm-mc -filetype=obj -triple=riscv64 diff_priv_spec.s -o diff_priv_spec.o
@@ -286,6 +319,175 @@
 .attribute priv_spec, 3
 .attribute priv_spec_minor, 3
 
+#--- atomic_abi_unknown.s
+.attribute atomic_abi, 0
+
+#--- atomic_abi_A6C.s
+.attribute atomic_abi, 1
+
+#--- atomic_abi_A6S.s
+.attribute atomic_abi, 2
+
+#--- atomic_abi_A7.s
+.attribute atomic_abi, 3
+
+#      UNKNOWN_NONE: BuildAttributes {
+# UNKNOWN_NONE-NEXT:   FormatVersion: 0x41
+# UNKNOWN_NONE-NEXT:   Section 1 {
+# UNKNOWN_NONE-NEXT:     SectionLength: 17
+# UNKNOWN_NONE-NEXT:     Vendor: riscv
+# UNKNOWN_NONE-NEXT:     Tag: Tag_File (0x1)
+# UNKNOWN_NONE-NEXT:     Size: 7
+# UNKNOWN_NONE-NEXT:     FileAttributes {
+# UNKNOWN_NONE-NEXT:       Attribute {
+# UNKNOWN_NONE-NEXT:         Tag: 4
+# UNKNOWN_NONE-NEXT:         Value: 32
+# UNKNOWN_NONE-NEXT:         TagName: stack_align
+# UNKNOWN_NONE-NEXT:         Description: Stack alignment is 32-bytes
+# UNKNOWN_NONE-NEXT:       }
+# UNKNOWN_NONE-NEXT:     }
+# UNKNOWN_NONE-NEXT:   }
+# UNKNOWN_NONE-NEXT: }
+
+#      NONE_A6C: BuildAttributes {
+# NONE_A6C-NEXT:   FormatVersion: 0x41
+# NONE_A6C-NEXT:   Section 1 {
+# NONE_A6C-NEXT:     SectionLength: 19
+# NONE_A6C-NEXT:     Vendor: riscv
+# NONE_A6C-NEXT:     Tag: Tag_File (0x1)
+# NONE_A6C-NEXT:     Size: 9
+# NONE_A6C-NEXT:     FileAttributes {
+# NONE_A6C-NEXT:       Attribute {
+# NONE_A6C-NEXT:         Tag: 14
+# NONE_A6C-NEXT:         Value: 1
+# NONE_A6C-NEXT:         TagName: atomic_abi
+# NONE_A6C-NEXT:         Description: Atomic ABI is 1
+# NONE_A6C-NEXT:       }
+# NONE_A6C-NEXT:       Attribute {
+# NONE_A6C-NEXT:         Tag: 4
+# NONE_A6C-NEXT:         Value: 32
+# NONE_A6C-NEXT:         TagName: stack_align
+# NONE_A6C-NEXT:         Description: Stack alignment is 32-bytes
+# NONE_A6C-NEXT:       }
+# NONE_A6C-NEXT:     }
+# NONE_A6C-NEXT:   }
+# NONE_A6C-NEXT: }
+
+#      UNKNOWN_A6C: BuildAttributes {
+# UNKNOWN_A6C-NEXT:   FormatVersion: 0x41
+# UNKNOWN_A6C-NEXT:   Section 1 {
+# UNKNOWN_A6C-NEXT:     SectionLength: 17
+# UNKNOWN_A6C-NEXT:     Vendor: riscv
+# UNKNOWN_A6C-NEXT:     Tag: Tag_File (0x1)
+# UNKNOWN_A6C-NEXT:     Size: 7
+# UNKNOWN_A6C-NEXT:     FileAttributes {
+# UNKNOWN_A6C-NEXT:       Attribute {
+# UNKNOWN_A6C-NEXT:         Tag: 14
+# UNKNOWN_A6C-NEXT:         Value: 1
+# UNKNOWN_A6C-NEXT:         TagName: atomic_abi
+# UNKNOWN_A6C-NEXT:         Description: Atomic ABI is 1
+# UNKNOWN_A6C-NEXT:       }
+# UNKNOWN_A6C-NEXT:     }
+# UNKNOWN_A6C-NEXT:   }
+# UNKNOWN_A6C-NEXT: }
+
+#      UNKNOWN_A6S: BuildAttributes {
+# UNKNOWN_A6S-NEXT:   FormatVersion: 0x41
+# UNKNOWN_A6S-NEXT:   Section 1 {
+# UNKNOWN_A6S-NEXT:     SectionLength:
+# UNKNOWN_A6S-NEXT:     Vendor: riscv
+# UNKNOWN_A6S-NEXT:     Tag: Tag_File (0x1)
+# UNKNOWN_A6S-NEXT:     Size: 7
+# UNKNOWN_A6S-NEXT:     FileAttributes {
+# UNKNOWN_A6S-NEXT:       Attribute {
+# UNKNOWN_A6S-NEXT:         Tag: 14
+# UNKNOWN_A6S-NEXT:         Value: 2
+# UNKNOWN_A6S-NEXT:         TagName: atomic_abi
+# UNKNOWN_A6S-NEXT:         Description: Atomic ABI is 2
+# UNKNOWN_A6S-NEXT:       }
+# UNKNOWN_A6S-NEXT:     }
+# UNKNOWN_A6S-NEXT:   }
+# UNKNOWN_A6S-NEXT: }
+
+#      NONE_A7: BuildAttributes {
+# NONE_A7-NEXT:   FormatVersion: 0x41
+# NONE_A7-NEXT:   Section 1 {
+# NONE_A7-NEXT:     SectionLength: 19
+# NONE_A7-NEXT:     Vendor: riscv
+# NONE_A7-NEXT:     Tag: Tag_File (0x1)
+# NONE_A7-NEXT:     Size: 9
+# NONE_A7-NEXT:     FileAttributes {
+# NONE_A7-NEXT:       Attribute {
+# NONE_A7-NEXT:         Tag: 14
+# NONE_A7-NEXT:         Value: 3
+# NONE_A7-NEXT:         TagName: atomic_abi
+# NONE_A7-NEXT:         Description: Atomic ABI is 3
+# NONE_A7-NEXT:       }
+# NONE_A7-NEXT:       Attribute {
+# NONE_A7-NEXT:         Tag: 4
+# NONE_A7-NEXT:         Value: 32
+# NONE_A7-NEXT:         TagName: stack_align
+# NONE_A7-NEXT:         Description: Stack alignment is 32-bytes
+# NONE_A7-NEXT:       }
+# NONE_A7-NEXT:     }
+# NONE_A7-NEXT:   }
+# NONE_A7-NEXT: }
+
+
+#      UNKNOWN_A7: BuildAttributes {
+# UNKNOWN_A7-NEXT:   FormatVersion: 0x41
+# UNKNOWN_A7-NEXT:   Section 1 {
+# UNKNOWN_A7-NEXT:     SectionLength: 17
+# UNKNOWN_A7-NEXT:     Vendor: riscv
+# UNKNOWN_A7-NEXT:     Tag: Tag_File (0x1)
+# UNKNOWN_A7-NEXT:     Size: 7
+# UNKNOWN_A7-NEXT:     FileAttributes {
+# UNKNOWN_A7-NEXT:       Attribute {
+# UNKNOWN_A7-NEXT:         Tag: 14
+# UNKNOWN_A7-NEXT:         Value: 3
+# UNKNOWN_A7-NEXT:         TagName: atomic_abi
+# UNKNOWN_A7-NEXT:         Description: Atomic ABI is 3
+# UNKNOWN_A7-NEXT:       }
+# UNKNOWN_A7-NEXT:     }
+# UNKNOWN_A7-NEXT:   }
+# UNKNOWN_A7-NEXT: }
+
+#      A6C_A6S: BuildAttributes {
+# A6C_A6S-NEXT:   FormatVersion: 0x41
+# A6C_A6S-NEXT:   Section 1 {
+# A6C_A6S-NEXT:     SectionLength: 17
+# A6C_A6S-NEXT:     Vendor: riscv
+# A6C_A6S-NEXT:     Tag: Tag_File (0x1)
+# A6C_A6S-NEXT:     Size: 7
+# A6C_A6S-NEXT:     FileAttributes {
+# A6C_A6S-NEXT:       Attribute {
+# A6C_A6S-NEXT:         Tag: 14
+# A6C_A6S-NEXT:         Value: 1
+# A6C_A6S-NEXT:         TagName: atomic_abi
+# A6C_A6S-NEXT:         Description: Atomic ABI is 1
+# A6C_A6S-NEXT:       }
+# A6C_A6S-NEXT:     }
+# A6C_A6S-NEXT:   }
+# A6C_A6S-NEXT: }
+
+#      A6S_A7: BuildAttributes {
+# A6S_A7-NEXT:   FormatVersion: 0x41
+# A6S_A7-NEXT:   Section 1 {
+# A6S_A7-NEXT:     SectionLength: 17
+# A6S_A7-NEXT:     Vendor: riscv
+# A6S_A7-NEXT:     Tag: Tag_File (0x1)
+# A6S_A7-NEXT:     Size: 7
+# A6S_A7-NEXT:     FileAttributes {
+# A6S_A7-NEXT:       Attribute {
+# A6S_A7-NEXT:         Tag: 14
+# A6S_A7-NEXT:         Value: 3
+# A6S_A7-NEXT:         TagName: atomic_abi
+# A6S_A7-NEXT:         Description: Atomic ABI is 3
+# A6S_A7-NEXT:       }
+# A6S_A7-NEXT:     }
+# A6S_A7-NEXT:   }
+# A6S_A7-NEXT: }
+
 #--- unknown13.s
 .attribute 13, "0"
 #--- unknown13a.s
diff --git a/llvm/include/llvm/Support/RISCVAttributeParser.h b/llvm/include/llvm/Support/RISCVAttributeParser.h
index 305adffbe851e..9f295504de959 100644
--- a/llvm/include/llvm/Support/RISCVAttributeParser.h
+++ b/llvm/include/llvm/Support/RISCVAttributeParser.h
@@ -24,6 +24,7 @@ class RISCVAttributeParser : public ELFAttributeParser {
 
   Error unalignedAccess(unsigned tag);
   Error stackAlign(unsigned tag);
+  Error atomicAbi(unsigned tag);
 
 public:
   RISCVAttributeParser(ScopedPrinter *sw)
diff --git a/llvm/include/llvm/Support/RISCVAttributes.h b/llvm/include/llvm/Support/RISCVAttributes.h
index 18f5a84d21f25..5def890a72735 100644
--- a/llvm/include/llvm/Support/RISCVAttributes.h
+++ b/llvm/include/llvm/Support/RISCVAttributes.h
@@ -32,8 +32,21 @@ enum AttrType : unsigned {
   PRIV_SPEC = 8,
   PRIV_SPEC_MINOR = 10,
   PRIV_SPEC_REVISION = 12,
+  ATOMIC_ABI = 14,
 };
 
+namespace RISCVAtomicAbiTag {
+enum AtomicABI : unsigned {
+  // Values for Tag_RISCV_atomic_abi
+  // Defined at
+  // https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-elf.adoc#tag_riscv_atomic_abi-14-uleb128version
+  UNKNOWN = 0,
+  A6C = 1,
+  A6S = 2,
+  A7 = 3,
+};
+} // namespace RISCVAtomicAbiTag
+
 enum { NOT_ALLOWED = 0, ALLOWED = 1 };
 
 } // namespace RISCVAttrs
diff --git a/llvm/lib/Support/RISCVAttributeParser.cpp b/llvm/lib/Support/RISCVAttributeParser.cpp
index 7ce4b6ab161cd..19c5a0e06903f 100644
--- a/llvm/lib/Support/RISCVAttributeParser.cpp
+++ b/llvm/lib/Support/RISCVAttributeParser.cpp
@@ -36,7 +36,18 @@ const RISCVAttributeParser::DisplayHandler
         {
             RISCVAttrs::UNALIGNED_ACCESS,
             &RISCVAttributeParser::unalignedAccess,
-        }};
+        },
+        {
+            RISCVAttrs::ATOMIC_ABI,
+            &RISCVAttributeParser::atomicAbi,
+        },
+};
+
+Error RISCVAttributeParser::atomicAbi(unsigned Tag) {
+  uint64_t Value = de.getULEB128(cursor);
+  printAttribute(Tag, Value, "Atomic ABI is " + utostr(Value));
+  return Error::success();
+}
 
 Error RISCVAttributeParser::unalignedAccess(unsigned tag) {
   static const char *strings[] = {"No unaligned access", "Unaligned access"};
diff --git a/llvm/lib/Support/RISCVAttributes.cpp b/llvm/lib/Support/RISCVAttributes.cpp
index 9e629760d3d84..dc70d65acba06 100644
--- a/llvm/lib/Support/RISCVAttributes.cpp
+++ b/llvm/lib/Support/RISCVAttributes.cpp
@@ -18,6 +18,7 @@ static constexpr TagNameItem tagData[] = {
     {PRIV_SPEC, "Tag_priv_spec"},
     {PRIV_SPEC_MINOR, "Tag_priv_spec_minor"},
     {PRIV_SPEC_REVISION, "Tag_priv_spec_revision"},
+    {ATOMIC_ABI, "Tag_atomic_abi"},
 };
 
 constexpr TagNameMap RISCVAttributeTags{tagData};
diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
index 0f92e9ed6a64d..6f5f12cc72862 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
@@ -75,6 +75,13 @@ void RISCVTargetStreamer::emitTargetAttributes(const MCSubtargetInfo &STI,
     auto &ISAInfo = *ParseResult;
     emitTextAttribute(RISCVAttrs::ARCH, ISAInfo->toString());
   }
+
+  if (STI.hasFeature(RISCV::FeatureStdExtA)) {
+    unsigned AtomicABITag = STI.hasFeature(RISCV::FeatureTrailingSeqCstFence)
+                                ? RISCVAttrs::RISCVAtomicAbiTag::AtomicABI::A6S
+                                : RISCVAttrs::RISCVAtomicAbiTag::AtomicABI::A6C;
+    emitAttribute(RISCVAttrs::ATOMIC_ABI, AtomicABITag);
+  }
 }
 
 // This part is for ascii assembly output
diff --git a/llvm/test/CodeGen/RISCV/attributes.ll b/llvm/test/CodeGen/RISCV/attributes.ll
index 141d5ea418289..1aff3e8b83f40 100644
--- a/llvm/test/CodeGen/RISCV/attributes.ll
+++ b/llvm/test/CodeGen/RISCV/attributes.ll
@@ -129,7 +129,8 @@
 ; RUN: llc -mtriple=riscv64 -mattr=+m %s -o - | FileCheck --check-prefixes=CHECK,RV64M %s
 ; RUN: llc -mtriple=riscv64 -mattr=+zmmul %s -o - | FileCheck --check-prefixes=CHECK,RV64ZMMUL %s
 ; RUN: llc -mtriple=riscv64 -mattr=+m,+zmmul %s -o - | FileCheck --check-prefixes=CHECK,RV64MZMMUL %s
-; RUN: llc -mtriple=riscv64 -mattr=+a %s -o - | FileCheck --check-prefixes=CHECK,RV64A %s
+; RUN: llc -mtriple=riscv64 -mattr=+a %s -o - | FileCheck --check-prefixes=CHECK,RV64A,A6C %s
+; RUN: llc -mtriple=riscv64 -mattr=+a,+seq-cst-trailing-fence %s -o - | FileCheck --check-prefixes=CHECK,RV64A,A6S %s
 ; RUN: llc -mtriple=riscv64 -mattr=+f %s -o - | FileCheck --check-prefixes=CHECK,RV64F %s
 ; RUN: llc -mtriple=riscv64 -mattr=+d %s -o - | FileCheck --check-prefixes=CHECK,RV64D %s
 ; RUN: llc -mtriple=riscv64 -mattr=+c %s -o - | FileCheck --check-prefixes=CHECK,RV64C %s
@@ -516,3 +517,10 @@ define i32 @addi(i32 %a) {
   %1 = add i32 %a, 1
   ret i32 %1
 }
+
+define i8 @atomic_load_i8_seq_cst(ptr %a) nounwind {
+  %1 = load atomic i8, ptr %a seq_cst, align 1
+  ret i8 %1
+; A6S: .attribute 14, 2
+; A6C: .attribute 14, 1
+}
diff --git a/llvm/test/MC/RISCV/attribute.s b/llvm/test/MC/RISCV/attribute.s
index 56f0cb1daf176..75b9c65ed1cc2 100644
--- a/llvm/test/MC/RISCV/attribute.s
+++ b/llvm/test/MC/RISCV/attribute.s
@@ -24,3 +24,6 @@
 
 .attribute priv_spec_revision, 0
 # CHECK: attribute      12, 0
+
+.attribute atomic_abi, 0
+# CHECK: attribute      14, 0
diff --git a/llvm/test/MC/RISCV/invalid-attribute.s b/llvm/test/MC/RISCV/invalid-attribute.s
index 1d732af83cda3..2ebf7ddc9aff8 100644
--- a/llvm/test/MC/RISCV/invalid-attribute.s
+++ b/llvm/test/MC/RISCV/invalid-attribute.s
@@ -33,3 +33,6 @@
 
 .attribute arch, 30
 # CHECK: [[@LINE-1]]:18: error: expected string constant
+
+.attribute atomic_abi, "16"
+# CHECK: [[@LINE-1]]:24: error: expected numeric constant

>From 849a8be7ec4083635243a5307dcbdb796a4925d7 Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulkirth at google.com>
Date: Thu, 2 May 2024 09:11:21 -0700
Subject: [PATCH 2/8] Remove braces and clean up LLD test

Created using spr 1.3.4
---
 lld/ELF/Arch/RISCV.cpp          | 9 ++++-----
 lld/test/ELF/riscv-attributes.s | 3 +--
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/lld/ELF/Arch/RISCV.cpp b/lld/ELF/Arch/RISCV.cpp
index 7b9c9c6c6c385..7b3116ef1afdd 100644
--- a/lld/ELF/Arch/RISCV.cpp
+++ b/lld/ELF/Arch/RISCV.cpp
@@ -1103,7 +1103,7 @@ static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
       it->getSecond() = AtomicABI::A6C;
       return;
     case AtomicABI::A7:
-      error(toString(oldSection) + " has atomic_abi=" + Twine(oldTag) +
+      errorOrWarn(toString(oldSection) + " has atomic_abi=" + Twine(oldTag) +
             " but " + toString(newSection) +
             " has atomic_abi=" + Twine(newTag));
       return;
@@ -1125,7 +1125,7 @@ static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
       it->getSecond() = AtomicABI::A7;
       return;
     case AtomicABI::A6C:
-      error(toString(oldSection) + " has atomic_abi=" + Twine(oldTag) +
+      errorOrWarn(toString(oldSection) + " has atomic_abi=" + Twine(oldTag) +
             " but " + toString(newSection) +
             " has atomic_abi=" + Twine(newTag));
       return;
@@ -1190,11 +1190,10 @@ mergeAttributesSection(const SmallVector<InputSectionBase *, 0> &sections) {
       case llvm::RISCVAttrs::AttrType::ATOMIC_ABI:
         if (auto i = parser.getAttributeValue(tag.attr)) {
           auto r = merged.intAttr.try_emplace(tag.attr, *i);
-          if (r.second) {
+          if (r.second)
             firstAtomicAbi = sec;
-          } else {
+          else
             mergeAtomic(r.first, firstAtomicAbi, sec, r.first->getSecond(), *i);
-          }
         }
         continue;
       }
diff --git a/lld/test/ELF/riscv-attributes.s b/lld/test/ELF/riscv-attributes.s
index 77c2c3cb263fd..70bcd10c0a4fa 100644
--- a/lld/test/ELF/riscv-attributes.s
+++ b/lld/test/ELF/riscv-attributes.s
@@ -44,13 +44,12 @@
 # RUN: not ld.lld a.o b.o c.o diff_stack_align.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=STACK_ALIGN --implicit-check-not=error:
 # STACK_ALIGN: error: diff_stack_align.o:(.riscv.attributes) has stack_align=32 but a.o:(.riscv.attributes) has stack_align=16
 
-## merging atomic_abi values for A6C and A7 lead to an error.
+## RISC-V tag merging for atomic_abi values A6C and A7 lead to an error.
 # RUN: llvm-mc -filetype=obj -triple=riscv64  atomic_abi_A6C.s -o atomic_abi_A6C.o
 # RUN: llvm-mc -filetype=obj -triple=riscv64  atomic_abi_A7.s -o atomic_abi_A7.o
 # RUN: not ld.lld atomic_abi_A6C.o atomic_abi_A7.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=ATOMIC_ABI_ERROR --implicit-check-not=error:
 # ATOMIC_ABI_ERROR: error: atomic_abi_A6C.o:(.riscv.attributes) has atomic_abi=1 but atomic_abi_A7.o:(.riscv.attributes) has atomic_abi=3
 
-
 # RUN: llvm-mc -filetype=obj -triple=riscv64  atomic_abi_A6S.s -o atomic_abi_A6S.o
 # RUN: ld.lld atomic_abi_A6S.o atomic_abi_A6C.o -o atomic_abi_A6C_A6S
 # RUN: llvm-readobj -A atomic_abi_A6C_A6S | FileCheck %s --check-prefix=A6C_A6S

>From 907f6f01b4ff8831cb852d747acd11d480d5757e Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulkirth at google.com>
Date: Thu, 2 May 2024 09:13:33 -0700
Subject: [PATCH 3/8] git clang-format

Created using spr 1.3.4
---
 lld/ELF/Arch/RISCV.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lld/ELF/Arch/RISCV.cpp b/lld/ELF/Arch/RISCV.cpp
index 7b3116ef1afdd..0a11ab9a6f93c 100644
--- a/lld/ELF/Arch/RISCV.cpp
+++ b/lld/ELF/Arch/RISCV.cpp
@@ -1104,8 +1104,8 @@ static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
       return;
     case AtomicABI::A7:
       errorOrWarn(toString(oldSection) + " has atomic_abi=" + Twine(oldTag) +
-            " but " + toString(newSection) +
-            " has atomic_abi=" + Twine(newTag));
+                  " but " + toString(newSection) +
+                  " has atomic_abi=" + Twine(newTag));
       return;
     };
 
@@ -1126,8 +1126,8 @@ static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
       return;
     case AtomicABI::A6C:
       errorOrWarn(toString(oldSection) + " has atomic_abi=" + Twine(oldTag) +
-            " but " + toString(newSection) +
-            " has atomic_abi=" + Twine(newTag));
+                  " but " + toString(newSection) +
+                  " has atomic_abi=" + Twine(newTag));
       return;
     };
   default:

>From 0f0a91827e4538fdc633c22ed046a3dce98a2697 Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulkirth at google.com>
Date: Thu, 9 May 2024 17:21:28 -0700
Subject: [PATCH 4/8] Add flag for attributes emmission

Created using spr 1.3.4
---
 llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp | 3 ++-
 llvm/lib/Target/RISCV/RISCVFeatures.td                     | 3 +++
 llvm/test/CodeGen/RISCV/attributes.ll                      | 4 ++--
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
index 6f5f12cc72862..45ca0f4b57dd4 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
@@ -76,7 +76,8 @@ void RISCVTargetStreamer::emitTargetAttributes(const MCSubtargetInfo &STI,
     emitTextAttribute(RISCVAttrs::ARCH, ISAInfo->toString());
   }
 
-  if (STI.hasFeature(RISCV::FeatureStdExtA)) {
+  if (STI.hasFeature(RISCV::FeatureAbiAttributes) &&
+      STI.hasFeature(RISCV::FeatureStdExtA)) {
     unsigned AtomicABITag = STI.hasFeature(RISCV::FeatureTrailingSeqCstFence)
                                 ? RISCVAttrs::RISCVAtomicAbiTag::AtomicABI::A6S
                                 : RISCVAttrs::RISCVAtomicAbiTag::AtomicABI::A6C;
diff --git a/llvm/lib/Target/RISCV/RISCVFeatures.td b/llvm/lib/Target/RISCV/RISCVFeatures.td
index c3dc4ea53697c..c1d0d01082d0f 100644
--- a/llvm/lib/Target/RISCV/RISCVFeatures.td
+++ b/llvm/lib/Target/RISCV/RISCVFeatures.td
@@ -1221,6 +1221,9 @@ def FeatureTrailingSeqCstFence : SubtargetFeature<"seq-cst-trailing-fence",
                                           "true",
                                           "Enable trailing fence for seq-cst store.">;
 
+def FeatureAbiAttributes : SubtargetFeature<"abi-attr", "EnableAbiAttributes",
+                                            "true", "Enable emitting RISC-V ABI attributes">;
+
 def FeatureUnalignedScalarMem
    : SubtargetFeature<"unaligned-scalar-mem", "EnableUnalignedScalarMem",
                       "true", "Has reasonably performant unaligned scalar "
diff --git a/llvm/test/CodeGen/RISCV/attributes.ll b/llvm/test/CodeGen/RISCV/attributes.ll
index 1aff3e8b83f40..272659d8d2ebe 100644
--- a/llvm/test/CodeGen/RISCV/attributes.ll
+++ b/llvm/test/CodeGen/RISCV/attributes.ll
@@ -129,8 +129,8 @@
 ; RUN: llc -mtriple=riscv64 -mattr=+m %s -o - | FileCheck --check-prefixes=CHECK,RV64M %s
 ; RUN: llc -mtriple=riscv64 -mattr=+zmmul %s -o - | FileCheck --check-prefixes=CHECK,RV64ZMMUL %s
 ; RUN: llc -mtriple=riscv64 -mattr=+m,+zmmul %s -o - | FileCheck --check-prefixes=CHECK,RV64MZMMUL %s
-; RUN: llc -mtriple=riscv64 -mattr=+a %s -o - | FileCheck --check-prefixes=CHECK,RV64A,A6C %s
-; RUN: llc -mtriple=riscv64 -mattr=+a,+seq-cst-trailing-fence %s -o - | FileCheck --check-prefixes=CHECK,RV64A,A6S %s
+; RUN: llc -mtriple=riscv64 -mattr=+a,+abi-attr %s -o - | FileCheck --check-prefixes=CHECK,RV64A,A6C %s
+; RUN: llc -mtriple=riscv64 -mattr=+a,+seq-cst-trailing-fence,+abi-attr %s -o - | FileCheck --check-prefixes=CHECK,RV64A,A6S %s
 ; RUN: llc -mtriple=riscv64 -mattr=+f %s -o - | FileCheck --check-prefixes=CHECK,RV64F %s
 ; RUN: llc -mtriple=riscv64 -mattr=+d %s -o - | FileCheck --check-prefixes=CHECK,RV64D %s
 ; RUN: llc -mtriple=riscv64 -mattr=+c %s -o - | FileCheck --check-prefixes=CHECK,RV64C %s

>From 4742ccb514d2949b58cc500e4e448426e153335c Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulkirth at google.com>
Date: Mon, 1 Jul 2024 10:45:25 -0700
Subject: [PATCH 5/8] Try to make the mergeAtomic API more natural

Created using spr 1.3.4
---
 lld/ELF/Arch/RISCV.cpp | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/lld/ELF/Arch/RISCV.cpp b/lld/ELF/Arch/RISCV.cpp
index 1d9be92601006..102e8235e27af 100644
--- a/lld/ELF/Arch/RISCV.cpp
+++ b/lld/ELF/Arch/RISCV.cpp
@@ -1086,27 +1086,28 @@ static void mergeArch(RISCVISAUtils::OrderedExtensionMap &mergedExts,
 
 static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
                         const InputSectionBase *oldSection,
-                        const InputSectionBase *newSection, unsigned int oldTag,
-                        unsigned int newTag) {
+                        const InputSectionBase *newSection,
+                        RISCVAttrs::RISCVAtomicAbiTag oldTag,
+                        RISCVAttrs::RISCVAtomicAbiTag newTag) {
   using RISCVAttrs::RISCVAtomicAbiTag;
   // Same tags stay the same, and UNKNOWN is compatible with anything
-  if (oldTag == newTag ||
-      newTag == static_cast<unsigned>(RISCVAtomicAbiTag::UNKNOWN))
+  if (oldTag == newTag || newTag == RISCVAtomicAbiTag::UNKNOWN)
     return;
 
   auto reportAbiError = [&]() {
     errorOrWarn("atomic abi mismatch for " + oldSection->name + "\n>>> " +
-                toString(oldSection) + ": atomic_abi=" + Twine(oldTag) +
+                toString(oldSection) +
+                ": atomic_abi=" + Twine(static_cast<unsigned>(oldTag)) +
                 "\n>>> " + toString(newSection) +
-                ": atomic_abi=" + Twine(newTag));
+                ": atomic_abi=" + Twine(static_cast<unsigned>(newTag)));
   };
 
   switch (static_cast<RISCVAtomicAbiTag>(oldTag)) {
   case RISCVAtomicAbiTag::UNKNOWN:
-    it->getSecond() = newTag;
+    it->getSecond() = static_cast<unsigned>(newTag);
     return;
   case RISCVAtomicAbiTag::A6C:
-    switch (static_cast<RISCVAtomicAbiTag>(newTag)) {
+    switch (newTag) {
     case RISCVAtomicAbiTag::A6S:
       it->getSecond() = static_cast<unsigned>(RISCVAtomicAbiTag::A6C);
       return;
@@ -1120,7 +1121,7 @@ static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
     break;
 
   case RISCVAtomicAbiTag::A6S:
-    switch (static_cast<RISCVAtomicAbiTag>(newTag)) {
+    switch (newTag) {
     case RISCVAtomicAbiTag::A6C:
       it->getSecond() = static_cast<unsigned>(RISCVAtomicAbiTag::A6C);
       return;
@@ -1134,7 +1135,7 @@ static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
     break;
 
   case RISCVAtomicAbiTag::A7:
-    switch (static_cast<RISCVAtomicAbiTag>(newTag)) {
+    switch (newTag) {
     case RISCVAtomicAbiTag::A6S:
       it->getSecond() = static_cast<unsigned>(RISCVAtomicAbiTag::A7);
       return;
@@ -1151,6 +1152,7 @@ static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
 
 static RISCVAttributesSection *
 mergeAttributesSection(const SmallVector<InputSectionBase *, 0> &sections) {
+  using RISCVAttrs::RISCVAtomicAbiTag;
   RISCVISAUtils::OrderedExtensionMap exts;
   const InputSectionBase *firstStackAlign = nullptr;
   const InputSectionBase *firstAtomicAbi = nullptr;
@@ -1207,7 +1209,9 @@ mergeAttributesSection(const SmallVector<InputSectionBase *, 0> &sections) {
           if (r.second)
             firstAtomicAbi = sec;
           else
-            mergeAtomic(r.first, firstAtomicAbi, sec, r.first->getSecond(), *i);
+            mergeAtomic(r.first, firstAtomicAbi, sec,
+                        static_cast<RISCVAtomicAbiTag>(r.first->getSecond()),
+                        static_cast<RISCVAtomicAbiTag>(*i));
         }
         continue;
       }

>From b408b8e7aa80395f052acd8352adb1ee72c2773b Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulkirth at google.com>
Date: Mon, 1 Jul 2024 10:54:03 -0700
Subject: [PATCH 6/8] Simplify switch logic w/ return

Created using spr 1.3.4
---
 lld/ELF/Arch/RISCV.cpp | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/lld/ELF/Arch/RISCV.cpp b/lld/ELF/Arch/RISCV.cpp
index 102e8235e27af..aa11aaa61a532 100644
--- a/lld/ELF/Arch/RISCV.cpp
+++ b/lld/ELF/Arch/RISCV.cpp
@@ -1116,9 +1116,8 @@ static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
       return;
     case RISCVAttrs::RISCVAtomicAbiTag::UNKNOWN:
     case RISCVAttrs::RISCVAtomicAbiTag::A6C:
-      break;
+      return;
     };
-    break;
 
   case RISCVAtomicAbiTag::A6S:
     switch (newTag) {
@@ -1130,9 +1129,8 @@ static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
       return;
     case RISCVAttrs::RISCVAtomicAbiTag::UNKNOWN:
     case RISCVAttrs::RISCVAtomicAbiTag::A6S:
-      break;
+      return;
     };
-    break;
 
   case RISCVAtomicAbiTag::A7:
     switch (newTag) {
@@ -1144,7 +1142,7 @@ static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
       return;
     case RISCVAttrs::RISCVAtomicAbiTag::UNKNOWN:
     case RISCVAttrs::RISCVAtomicAbiTag::A7:
-      break;
+      return;
     };
   };
   llvm_unreachable("unknown AtomicABI");

>From af797bb73b9c61482de31c13a5b85cf16d67f1f0 Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulkirth at google.com>
Date: Mon, 1 Jul 2024 10:56:59 -0700
Subject: [PATCH 7/8] clang-format

Created using spr 1.3.4
---
 .../lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
index 95c851bde6750..edc4d72d6b434 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
@@ -23,10 +23,10 @@ using namespace llvm;
 
 // This option controls wether or not we emit ELF attributes for ABI features,
 // like RISC-V atomics or X3 usage.
-static cl::opt<bool>
-    RiscvAbiAttr("riscv-abi-attributes",
-              cl::desc("Enable emitting RISC-V ELF attributes for ABI features"),
-              cl::init(false), cl::Hidden);
+static cl::opt<bool> RiscvAbiAttr(
+    "riscv-abi-attributes",
+    cl::desc("Enable emitting RISC-V ELF attributes for ABI features"),
+    cl::init(false), cl::Hidden);
 
 RISCVTargetStreamer::RISCVTargetStreamer(MCStreamer &S) : MCTargetStreamer(S) {}
 

>From ae9b94b93da2afb14f5b8a3f85c64c039efecb71 Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulkirth at google.com>
Date: Mon, 1 Jul 2024 13:54:50 -0700
Subject: [PATCH 8/8] Split linker changes into separate patch

Created using spr 1.3.4
---
 lld/ELF/Arch/RISCV.cpp          |  78 ------------
 lld/test/ELF/riscv-attributes.s | 203 --------------------------------
 2 files changed, 281 deletions(-)

diff --git a/lld/ELF/Arch/RISCV.cpp b/lld/ELF/Arch/RISCV.cpp
index aa11aaa61a532..e4d63250135e0 100644
--- a/lld/ELF/Arch/RISCV.cpp
+++ b/lld/ELF/Arch/RISCV.cpp
@@ -1084,76 +1084,10 @@ static void mergeArch(RISCVISAUtils::OrderedExtensionMap &mergedExts,
   }
 }
 
-static void mergeAtomic(DenseMap<unsigned, unsigned>::iterator it,
-                        const InputSectionBase *oldSection,
-                        const InputSectionBase *newSection,
-                        RISCVAttrs::RISCVAtomicAbiTag oldTag,
-                        RISCVAttrs::RISCVAtomicAbiTag newTag) {
-  using RISCVAttrs::RISCVAtomicAbiTag;
-  // Same tags stay the same, and UNKNOWN is compatible with anything
-  if (oldTag == newTag || newTag == RISCVAtomicAbiTag::UNKNOWN)
-    return;
-
-  auto reportAbiError = [&]() {
-    errorOrWarn("atomic abi mismatch for " + oldSection->name + "\n>>> " +
-                toString(oldSection) +
-                ": atomic_abi=" + Twine(static_cast<unsigned>(oldTag)) +
-                "\n>>> " + toString(newSection) +
-                ": atomic_abi=" + Twine(static_cast<unsigned>(newTag)));
-  };
-
-  switch (static_cast<RISCVAtomicAbiTag>(oldTag)) {
-  case RISCVAtomicAbiTag::UNKNOWN:
-    it->getSecond() = static_cast<unsigned>(newTag);
-    return;
-  case RISCVAtomicAbiTag::A6C:
-    switch (newTag) {
-    case RISCVAtomicAbiTag::A6S:
-      it->getSecond() = static_cast<unsigned>(RISCVAtomicAbiTag::A6C);
-      return;
-    case RISCVAtomicAbiTag::A7:
-      reportAbiError();
-      return;
-    case RISCVAttrs::RISCVAtomicAbiTag::UNKNOWN:
-    case RISCVAttrs::RISCVAtomicAbiTag::A6C:
-      return;
-    };
-
-  case RISCVAtomicAbiTag::A6S:
-    switch (newTag) {
-    case RISCVAtomicAbiTag::A6C:
-      it->getSecond() = static_cast<unsigned>(RISCVAtomicAbiTag::A6C);
-      return;
-    case RISCVAtomicAbiTag::A7:
-      it->getSecond() = static_cast<unsigned>(RISCVAtomicAbiTag::A7);
-      return;
-    case RISCVAttrs::RISCVAtomicAbiTag::UNKNOWN:
-    case RISCVAttrs::RISCVAtomicAbiTag::A6S:
-      return;
-    };
-
-  case RISCVAtomicAbiTag::A7:
-    switch (newTag) {
-    case RISCVAtomicAbiTag::A6S:
-      it->getSecond() = static_cast<unsigned>(RISCVAtomicAbiTag::A7);
-      return;
-    case RISCVAtomicAbiTag::A6C:
-      reportAbiError();
-      return;
-    case RISCVAttrs::RISCVAtomicAbiTag::UNKNOWN:
-    case RISCVAttrs::RISCVAtomicAbiTag::A7:
-      return;
-    };
-  };
-  llvm_unreachable("unknown AtomicABI");
-}
-
 static RISCVAttributesSection *
 mergeAttributesSection(const SmallVector<InputSectionBase *, 0> &sections) {
-  using RISCVAttrs::RISCVAtomicAbiTag;
   RISCVISAUtils::OrderedExtensionMap exts;
   const InputSectionBase *firstStackAlign = nullptr;
-  const InputSectionBase *firstAtomicAbi = nullptr;
   unsigned firstStackAlignValue = 0, xlen = 0;
   bool hasArch = false;
 
@@ -1200,18 +1134,6 @@ mergeAttributesSection(const SmallVector<InputSectionBase *, 0> &sections) {
       case RISCVAttrs::PRIV_SPEC_MINOR:
       case RISCVAttrs::PRIV_SPEC_REVISION:
         break;
-
-      case llvm::RISCVAttrs::AttrType::ATOMIC_ABI:
-        if (auto i = parser.getAttributeValue(tag.attr)) {
-          auto r = merged.intAttr.try_emplace(tag.attr, *i);
-          if (r.second)
-            firstAtomicAbi = sec;
-          else
-            mergeAtomic(r.first, firstAtomicAbi, sec,
-                        static_cast<RISCVAtomicAbiTag>(r.first->getSecond()),
-                        static_cast<RISCVAtomicAbiTag>(*i));
-        }
-        continue;
       }
 
       // Fallback for deprecated priv_spec* and other unknown attributes: retain
diff --git a/lld/test/ELF/riscv-attributes.s b/lld/test/ELF/riscv-attributes.s
index 38b0fe8e7797e..68534d0fb6b75 100644
--- a/lld/test/ELF/riscv-attributes.s
+++ b/lld/test/ELF/riscv-attributes.s
@@ -44,40 +44,6 @@
 # RUN: not ld.lld a.o b.o c.o diff_stack_align.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=STACK_ALIGN --implicit-check-not=error:
 # STACK_ALIGN: error: diff_stack_align.o:(.riscv.attributes) has stack_align=32 but a.o:(.riscv.attributes) has stack_align=16
 
-## RISC-V tag merging for atomic_abi values A6C and A7 lead to an error.
-# RUN: llvm-mc -filetype=obj -triple=riscv64  atomic_abi_A6C.s -o atomic_abi_A6C.o
-# RUN: llvm-mc -filetype=obj -triple=riscv64  atomic_abi_A7.s -o atomic_abi_A7.o
-# RUN: not ld.lld atomic_abi_A6C.o atomic_abi_A7.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=ATOMIC_ABI_ERROR --implicit-check-not=error:
-# ATOMIC_ABI_ERROR: error: atomic abi mismatch for .riscv.attributes
-# ATOMIC_ABI_ERROR-NEXT: >>> atomic_abi_A6C.o:(.riscv.attributes): atomic_abi=1
-# ATOMIC_ABI_ERROR-NEXT: >>> atomic_abi_A7.o:(.riscv.attributes): atomic_abi=3
-
-# RUN: llvm-mc -filetype=obj -triple=riscv64  atomic_abi_A6S.s -o atomic_abi_A6S.o
-# RUN: ld.lld atomic_abi_A6S.o atomic_abi_A6C.o -o atomic_abi_A6C_A6S
-# RUN: llvm-readobj -A atomic_abi_A6C_A6S | FileCheck %s --check-prefix=A6C_A6S
-
-# RUN: ld.lld atomic_abi_A6S.o atomic_abi_A7.o -o atomic_abi_A6S_A7
-# RUN: llvm-readobj -A atomic_abi_A6S_A7 | FileCheck %s --check-prefix=A6S_A7
-
-# RUN: llvm-mc -filetype=obj -triple=riscv64  atomic_abi_unknown.s -o atomic_abi_unknown.o
-# RUN: ld.lld atomic_abi_unknown.o atomic_abi_A6C.o -o atomic_abi_A6C_unknown
-# RUN: llvm-readobj -A atomic_abi_A6C_unknown | FileCheck %s --check-prefixes=UNKNOWN_A6C
-
-# RUN: ld.lld atomic_abi_unknown.o diff_stack_align.o -o atomic_abi_none_unknown
-# RUN: llvm-readobj -A atomic_abi_none_unknown | FileCheck %s --check-prefixes=UNKNOWN_NONE
-
-# RUN: ld.lld diff_stack_align.o atomic_abi_A6C.o -o atomic_abi_A6C_none
-# RUN: llvm-readobj -A atomic_abi_A6C_none | FileCheck %s --check-prefixes=NONE_A6C
-
-# RUN: ld.lld atomic_abi_unknown.o atomic_abi_A6S.o -o atomic_abi_A6S_unknown
-# RUN: llvm-readobj -A atomic_abi_A6S_unknown | FileCheck %s --check-prefix=UNKNOWN_A6S
-
-# RUN: ld.lld atomic_abi_unknown.o atomic_abi_A7.o -o atomic_abi_A7_unknown
-# RUN: llvm-readobj -A atomic_abi_A7_unknown | FileCheck %s --check-prefix=UNKNOWN_A7
-
-# RUN: ld.lld diff_stack_align.o atomic_abi_A7.o -o atomic_abi_A7_none
-# RUN: llvm-readobj -A atomic_abi_A7_none | FileCheck %s --check-prefix=NONE_A7
-
 ## The deprecated priv_spec is not handled as GNU ld does.
 ## Differing priv_spec attributes lead to an absent attribute.
 # RUN: llvm-mc -filetype=obj -triple=riscv64 diff_priv_spec.s -o diff_priv_spec.o
@@ -320,175 +286,6 @@
 .attribute priv_spec, 3
 .attribute priv_spec_minor, 3
 
-#--- atomic_abi_unknown.s
-.attribute atomic_abi, 0
-
-#--- atomic_abi_A6C.s
-.attribute atomic_abi, 1
-
-#--- atomic_abi_A6S.s
-.attribute atomic_abi, 2
-
-#--- atomic_abi_A7.s
-.attribute atomic_abi, 3
-
-#      UNKNOWN_NONE: BuildAttributes {
-# UNKNOWN_NONE-NEXT:   FormatVersion: 0x41
-# UNKNOWN_NONE-NEXT:   Section 1 {
-# UNKNOWN_NONE-NEXT:     SectionLength: 17
-# UNKNOWN_NONE-NEXT:     Vendor: riscv
-# UNKNOWN_NONE-NEXT:     Tag: Tag_File (0x1)
-# UNKNOWN_NONE-NEXT:     Size: 7
-# UNKNOWN_NONE-NEXT:     FileAttributes {
-# UNKNOWN_NONE-NEXT:       Attribute {
-# UNKNOWN_NONE-NEXT:         Tag: 4
-# UNKNOWN_NONE-NEXT:         Value: 32
-# UNKNOWN_NONE-NEXT:         TagName: stack_align
-# UNKNOWN_NONE-NEXT:         Description: Stack alignment is 32-bytes
-# UNKNOWN_NONE-NEXT:       }
-# UNKNOWN_NONE-NEXT:     }
-# UNKNOWN_NONE-NEXT:   }
-# UNKNOWN_NONE-NEXT: }
-
-#      NONE_A6C: BuildAttributes {
-# NONE_A6C-NEXT:   FormatVersion: 0x41
-# NONE_A6C-NEXT:   Section 1 {
-# NONE_A6C-NEXT:     SectionLength: 19
-# NONE_A6C-NEXT:     Vendor: riscv
-# NONE_A6C-NEXT:     Tag: Tag_File (0x1)
-# NONE_A6C-NEXT:     Size: 9
-# NONE_A6C-NEXT:     FileAttributes {
-# NONE_A6C-NEXT:       Attribute {
-# NONE_A6C-NEXT:         Tag: 14
-# NONE_A6C-NEXT:         Value: 1
-# NONE_A6C-NEXT:         TagName: atomic_abi
-# NONE_A6C-NEXT:         Description: Atomic ABI is 1
-# NONE_A6C-NEXT:       }
-# NONE_A6C-NEXT:       Attribute {
-# NONE_A6C-NEXT:         Tag: 4
-# NONE_A6C-NEXT:         Value: 32
-# NONE_A6C-NEXT:         TagName: stack_align
-# NONE_A6C-NEXT:         Description: Stack alignment is 32-bytes
-# NONE_A6C-NEXT:       }
-# NONE_A6C-NEXT:     }
-# NONE_A6C-NEXT:   }
-# NONE_A6C-NEXT: }
-
-#      UNKNOWN_A6C: BuildAttributes {
-# UNKNOWN_A6C-NEXT:   FormatVersion: 0x41
-# UNKNOWN_A6C-NEXT:   Section 1 {
-# UNKNOWN_A6C-NEXT:     SectionLength: 17
-# UNKNOWN_A6C-NEXT:     Vendor: riscv
-# UNKNOWN_A6C-NEXT:     Tag: Tag_File (0x1)
-# UNKNOWN_A6C-NEXT:     Size: 7
-# UNKNOWN_A6C-NEXT:     FileAttributes {
-# UNKNOWN_A6C-NEXT:       Attribute {
-# UNKNOWN_A6C-NEXT:         Tag: 14
-# UNKNOWN_A6C-NEXT:         Value: 1
-# UNKNOWN_A6C-NEXT:         TagName: atomic_abi
-# UNKNOWN_A6C-NEXT:         Description: Atomic ABI is 1
-# UNKNOWN_A6C-NEXT:       }
-# UNKNOWN_A6C-NEXT:     }
-# UNKNOWN_A6C-NEXT:   }
-# UNKNOWN_A6C-NEXT: }
-
-#      UNKNOWN_A6S: BuildAttributes {
-# UNKNOWN_A6S-NEXT:   FormatVersion: 0x41
-# UNKNOWN_A6S-NEXT:   Section 1 {
-# UNKNOWN_A6S-NEXT:     SectionLength:
-# UNKNOWN_A6S-NEXT:     Vendor: riscv
-# UNKNOWN_A6S-NEXT:     Tag: Tag_File (0x1)
-# UNKNOWN_A6S-NEXT:     Size: 7
-# UNKNOWN_A6S-NEXT:     FileAttributes {
-# UNKNOWN_A6S-NEXT:       Attribute {
-# UNKNOWN_A6S-NEXT:         Tag: 14
-# UNKNOWN_A6S-NEXT:         Value: 2
-# UNKNOWN_A6S-NEXT:         TagName: atomic_abi
-# UNKNOWN_A6S-NEXT:         Description: Atomic ABI is 2
-# UNKNOWN_A6S-NEXT:       }
-# UNKNOWN_A6S-NEXT:     }
-# UNKNOWN_A6S-NEXT:   }
-# UNKNOWN_A6S-NEXT: }
-
-#      NONE_A7: BuildAttributes {
-# NONE_A7-NEXT:   FormatVersion: 0x41
-# NONE_A7-NEXT:   Section 1 {
-# NONE_A7-NEXT:     SectionLength: 19
-# NONE_A7-NEXT:     Vendor: riscv
-# NONE_A7-NEXT:     Tag: Tag_File (0x1)
-# NONE_A7-NEXT:     Size: 9
-# NONE_A7-NEXT:     FileAttributes {
-# NONE_A7-NEXT:       Attribute {
-# NONE_A7-NEXT:         Tag: 14
-# NONE_A7-NEXT:         Value: 3
-# NONE_A7-NEXT:         TagName: atomic_abi
-# NONE_A7-NEXT:         Description: Atomic ABI is 3
-# NONE_A7-NEXT:       }
-# NONE_A7-NEXT:       Attribute {
-# NONE_A7-NEXT:         Tag: 4
-# NONE_A7-NEXT:         Value: 32
-# NONE_A7-NEXT:         TagName: stack_align
-# NONE_A7-NEXT:         Description: Stack alignment is 32-bytes
-# NONE_A7-NEXT:       }
-# NONE_A7-NEXT:     }
-# NONE_A7-NEXT:   }
-# NONE_A7-NEXT: }
-
-
-#      UNKNOWN_A7: BuildAttributes {
-# UNKNOWN_A7-NEXT:   FormatVersion: 0x41
-# UNKNOWN_A7-NEXT:   Section 1 {
-# UNKNOWN_A7-NEXT:     SectionLength: 17
-# UNKNOWN_A7-NEXT:     Vendor: riscv
-# UNKNOWN_A7-NEXT:     Tag: Tag_File (0x1)
-# UNKNOWN_A7-NEXT:     Size: 7
-# UNKNOWN_A7-NEXT:     FileAttributes {
-# UNKNOWN_A7-NEXT:       Attribute {
-# UNKNOWN_A7-NEXT:         Tag: 14
-# UNKNOWN_A7-NEXT:         Value: 3
-# UNKNOWN_A7-NEXT:         TagName: atomic_abi
-# UNKNOWN_A7-NEXT:         Description: Atomic ABI is 3
-# UNKNOWN_A7-NEXT:       }
-# UNKNOWN_A7-NEXT:     }
-# UNKNOWN_A7-NEXT:   }
-# UNKNOWN_A7-NEXT: }
-
-#      A6C_A6S: BuildAttributes {
-# A6C_A6S-NEXT:   FormatVersion: 0x41
-# A6C_A6S-NEXT:   Section 1 {
-# A6C_A6S-NEXT:     SectionLength: 17
-# A6C_A6S-NEXT:     Vendor: riscv
-# A6C_A6S-NEXT:     Tag: Tag_File (0x1)
-# A6C_A6S-NEXT:     Size: 7
-# A6C_A6S-NEXT:     FileAttributes {
-# A6C_A6S-NEXT:       Attribute {
-# A6C_A6S-NEXT:         Tag: 14
-# A6C_A6S-NEXT:         Value: 1
-# A6C_A6S-NEXT:         TagName: atomic_abi
-# A6C_A6S-NEXT:         Description: Atomic ABI is 1
-# A6C_A6S-NEXT:       }
-# A6C_A6S-NEXT:     }
-# A6C_A6S-NEXT:   }
-# A6C_A6S-NEXT: }
-
-#      A6S_A7: BuildAttributes {
-# A6S_A7-NEXT:   FormatVersion: 0x41
-# A6S_A7-NEXT:   Section 1 {
-# A6S_A7-NEXT:     SectionLength: 17
-# A6S_A7-NEXT:     Vendor: riscv
-# A6S_A7-NEXT:     Tag: Tag_File (0x1)
-# A6S_A7-NEXT:     Size: 7
-# A6S_A7-NEXT:     FileAttributes {
-# A6S_A7-NEXT:       Attribute {
-# A6S_A7-NEXT:         Tag: 14
-# A6S_A7-NEXT:         Value: 3
-# A6S_A7-NEXT:         TagName: atomic_abi
-# A6S_A7-NEXT:         Description: Atomic ABI is 3
-# A6S_A7-NEXT:       }
-# A6S_A7-NEXT:     }
-# A6S_A7-NEXT:   }
-# A6S_A7-NEXT: }
-
 #--- unknown13.s
 .attribute 13, "0"
 #--- unknown13a.s



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