[llvm] 4fd5d93 - [RISCV] Emitting proper atomic ABI tag when Zalasr is enabled (#121017)

[via llvm-commits]

Author: Brendan Sweeney
Date: 2025-03-03T11:34:52-08:00
New Revision: 4fd5d935a3d30d20aed7697be5d8bb76dae8eab6

URL: https://github.com/llvm/llvm-project/commit/4fd5d935a3d30d20aed7697be5d8bb76dae8eab6
DIFF: https://github.com/llvm/llvm-project/commit/4fd5d935a3d30d20aed7697be5d8bb76dae8eab6.diff

LOG: [RISCV] Emitting proper atomic ABI tag when Zalasr is enabled (#121017)

When Zalasr is enabled, it will emit the A7 atomic ABI tag. Zalasr is
the load-acquire and store-release extension, and the reason A7 (and
A6S) exists is to support it.

The A7 atomic ABI is compatible with A6S (which is what is currently
emitted as the tag), but A7 is not compatible with A6C, while A6C and
A6S are compatible.


https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-atomic.adoc#risc-v-atomics-mappings


https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-elf.adoc#tag_riscv_atomic_abi-14-uleb128version

Added: 
    

Modified: 
    llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
    llvm/test/CodeGen/RISCV/attributes.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
index 72b3e56c8a72f..ce64c61034901 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVTargetStreamer.cpp
@@ -85,10 +85,13 @@ void RISCVTargetStreamer::emitTargetAttributes(const MCSubtargetInfo &STI,
   }
 
   if (RiscvAbiAttr && STI.hasFeature(RISCV::FeatureStdExtA)) {
-    unsigned AtomicABITag = static_cast<unsigned>(
-        STI.hasFeature(RISCV::FeatureNoTrailingSeqCstFence)
-            ? RISCVAttrs::RISCVAtomicAbiTag::A6C
-            : RISCVAttrs::RISCVAtomicAbiTag::A6S);
+    unsigned AtomicABITag;
+    if (STI.hasFeature(RISCV::FeatureStdExtZalasr))
+      AtomicABITag = static_cast<unsigned>(RISCVAttrs::RISCVAtomicAbiTag::A7);
+    else if (STI.hasFeature(RISCV::FeatureNoTrailingSeqCstFence))
+      AtomicABITag = static_cast<unsigned>(RISCVAttrs::RISCVAtomicAbiTag::A6C);
+    else
+      AtomicABITag = static_cast<unsigned>(RISCVAttrs::RISCVAtomicAbiTag::A6S);
     emitAttribute(RISCVAttrs::ATOMIC_ABI, AtomicABITag);
   }
 }

diff  --git a/llvm/test/CodeGen/RISCV/attributes.ll b/llvm/test/CodeGen/RISCV/attributes.ll
index 29f84dc79b6ae..7023f2577152b 100644
--- a/llvm/test/CodeGen/RISCV/attributes.ll
+++ b/llvm/test/CodeGen/RISCV/attributes.ll
@@ -160,6 +160,7 @@
 ; RUN: llc -mtriple=riscv64 -mattr=+m,+zmmul %s -o - | FileCheck --check-prefixes=CHECK,RV64MZMMUL %s
 ; RUN: llc -mtriple=riscv64 -mattr=+a,no-trailing-seq-cst-fence --riscv-abi-attributes %s -o - | FileCheck --check-prefixes=CHECK,RV64A,A6C %s
 ; RUN: llc -mtriple=riscv64 -mattr=+a --riscv-abi-attributes %s -o - | FileCheck --check-prefixes=CHECK,RV64A,A6S %s
+; RUN: llc -mtriple=riscv64 -mattr=+a,experimental-zalasr --riscv-abi-attributes %s -o - | FileCheck --check-prefixes=CHECK,RV64ZALASRA,A7 %s
 ; RUN: llc -mtriple=riscv64 -mattr=+b %s -o - | FileCheck --check-prefixes=CHECK,RV64B %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
@@ -608,6 +609,7 @@
 ; RV64ZVFBFWMA: .attribute 5, "rv64i2p1_f2p2_zicsr2p0_zfbfmin1p0_zve32f1p0_zve32x1p0_zvfbfmin1p0_zvfbfwma1p0_zvl32b1p0"
 ; RV64ZACAS: .attribute 5, "rv64i2p1_zaamo1p0_zacas1p0"
 ; RV64ZALASR: .attribute 5, "rv64i2p1_zalasr0p1"
+; RV64ZALASRA: .attribute 5, "rv64i2p1_a2p1_zaamo1p0_zalasr0p1_zalrsc1p0"
 ; RV64ZICFILP: .attribute 5, "rv64i2p1_zicfilp1p0_zicsr2p0"
 ; RV64ZABHA: .attribute 5, "rv64i2p1_zaamo1p0_zabha1p0"
 ; RV64ZVBC32E: .attribute 5, "rv64i2p1_zicsr2p0_zvbc32e0p7_zve32x1p0_zvl32b1p0"
@@ -645,4 +647,5 @@ define i8 @atomic_load_i8_seq_cst(ptr %a) nounwind {
   ret i8 %1
 ; A6S: .attribute 14, 2
 ; A6C: .attribute 14, 1
+; A7: .attribute 14, 3
 }