[RISCV] Zabha/Zacas implies Zaamo

[tclin914]

The Zabha/Zacas extension depends upon the Zaamo extension.
Ref: https://github.com/riscv/riscv-isa-manual/blob/main/src/zacas.adoc
https://github.com/riscv/riscv-isa-manual/blob/main/src/zabha.adoc.

[llvmbot]

@llvm/pr-subscribers-mc

@llvm/pr-subscribers-backend-risc-v

Author: Jim Lin (tclin914)

Changes

The Zabha/Zacas extension depends upon the Zaamo extension.
Ref: https://github.com/riscv/riscv-isa-manual/blob/main/src/zacas.adoc
https://github.com/riscv/riscv-isa-manual/blob/main/src/zabha.adoc.

---

Full diff: https://github.com/llvm/llvm-project/pull/115694.diff

5 Files Affected:

• (modified) llvm/lib/Target/RISCV/RISCVFeatures.td (+4-2)
• (modified) llvm/lib/TargetParser/RISCVISAInfo.cpp (-5)
• (modified) llvm/test/CodeGen/RISCV/attributes.ll (+4-4)
• (modified) llvm/test/MC/RISCV/attribute-arch.s (+1-1)
• (modified) llvm/unittests/TargetParser/RISCVISAInfoTest.cpp (-10)

diff --git a/llvm/lib/Target/RISCV/RISCVFeatures.td b/llvm/lib/Target/RISCV/RISCVFeatures.td
index ad733e1488b5ca..6ec7f9ab78c0d4 100644
--- a/llvm/lib/Target/RISCV/RISCVFeatures.td
+++ b/llvm/lib/Target/RISCV/RISCVFeatures.td
@@ -237,14 +237,16 @@ def HasStdExtAOrZaamo
 
 def FeatureStdExtZabha
     : RISCVExtension<"zabha", 1, 0,
-                     "'Zabha' (Byte and Halfword Atomic Memory Operations)">;
+                     "'Zabha' (Byte and Halfword Atomic Memory Operations)",
+                     [FeatureStdExtZaamo]>;
 def HasStdExtZabha : Predicate<"Subtarget->hasStdExtZabha()">,
                      AssemblerPredicate<(all_of FeatureStdExtZabha),
                          "'Zabha' (Byte and Halfword Atomic Memory Operations)">;
 
 def FeatureStdExtZacas
     : RISCVExtension<"zacas", 1, 0,
-                     "'Zacas' (Atomic Compare-And-Swap Instructions)">,
+                     "'Zacas' (Atomic Compare-And-Swap Instructions)",
+                     [FeatureStdExtZaamo]>,
       RISCVExtensionBitmask<0, 26>;
 def HasStdExtZacas : Predicate<"Subtarget->hasStdExtZacas()">,
                      AssemblerPredicate<(all_of FeatureStdExtZacas),
diff --git a/llvm/lib/TargetParser/RISCVISAInfo.cpp b/llvm/lib/TargetParser/RISCVISAInfo.cpp
index de5b5c39c9ed27..c1bc441fc3f63d 100644
--- a/llvm/lib/TargetParser/RISCVISAInfo.cpp
+++ b/llvm/lib/TargetParser/RISCVISAInfo.cpp
@@ -760,11 +760,6 @@ Error RISCVISAInfo::checkDependency() {
   if (XLen != 32 && Exts.count("zcf"))
     return getError("'zcf' is only supported for 'rv32'");
 
-  if (!(Exts.count("a") || Exts.count("zaamo")))
-    for (auto Ext : {"zacas", "zabha"})
-      if (Exts.count(Ext))
-        return getExtensionRequiresError(Ext, "a' or 'zaamo");
-
   if (Exts.count("xwchc") != 0) {
     if (XLen != 32)
       return getError("'xwchc' is only supported for 'rv32'");
diff --git a/llvm/test/CodeGen/RISCV/attributes.ll b/llvm/test/CodeGen/RISCV/attributes.ll
index 7624071f4f93ec..f61b403cc7c539 100644
--- a/llvm/test/CodeGen/RISCV/attributes.ll
+++ b/llvm/test/CodeGen/RISCV/attributes.ll
@@ -428,11 +428,11 @@
 ; RV32ZFBFMIN: .attribute 5, "rv32i2p1_f2p2_zicsr2p0_zfbfmin1p0"
 ; RV32ZVFBFMIN: .attribute 5, "rv32i2p1_f2p2_zicsr2p0_zve32f1p0_zve32x1p0_zvfbfmin1p0_zvl32b1p0"
 ; RV32ZVFBFWMA: .attribute 5, "rv32i2p1_f2p2_zicsr2p0_zfbfmin1p0_zve32f1p0_zve32x1p0_zvfbfmin1p0_zvfbfwma1p0_zvl32b1p0"
-; RV32ZACAS: .attribute 5, "rv32i2p1_a2p1_zacas1p0"
+; RV32ZACAS: .attribute 5, "rv32i2p1_a2p1_zaamo1p0_zacas1p0"
 ; RV32ZALASR: .attribute 5, "rv32i2p1_zalasr0p1"
 ; RV32ZAMA16B: .attribute 5, "rv32i2p1_zama16b1p0"
 ; RV32ZICFILP: .attribute 5, "rv32i2p1_zicfilp1p0_zicsr2p0"
-; RV32ZABHA: .attribute 5, "rv32i2p1_a2p1_zabha1p0"
+; RV32ZABHA: .attribute 5, "rv32i2p1_a2p1_zaamo1p0_zabha1p0"
 ; RV32ZVBC32E: .attribute 5, "rv32i2p1_zicsr2p0_zvbc32e0p7_zve32x1p0_zvl32b1p0"
 ; RV32ZVKGS: .attribute 5, "rv32i2p1_zicsr2p0_zve32x1p0_zvkg1p0_zvkgs0p7_zvl32b1p0"
 ; RV32SSNPM: .attribute 5, "rv32i2p1_ssnpm1p0"
@@ -574,10 +574,10 @@
 ; RV64ZFBFMIN: .attribute 5, "rv64i2p1_f2p2_zicsr2p0_zfbfmin1p0"
 ; RV64ZVFBFMIN: .attribute 5, "rv64i2p1_f2p2_zicsr2p0_zve32f1p0_zve32x1p0_zvfbfmin1p0_zvl32b1p0"
 ; RV64ZVFBFWMA: .attribute 5, "rv64i2p1_f2p2_zicsr2p0_zfbfmin1p0_zve32f1p0_zve32x1p0_zvfbfmin1p0_zvfbfwma1p0_zvl32b1p0"
-; RV64ZACAS: .attribute 5, "rv64i2p1_a2p1_zacas1p0"
+; RV64ZACAS: .attribute 5, "rv64i2p1_a2p1_zaamo1p0_zacas1p0"
 ; RV64ZALASR: .attribute 5, "rv64i2p1_zalasr0p1"
 ; RV64ZICFILP: .attribute 5, "rv64i2p1_zicfilp1p0_zicsr2p0"
-; RV64ZABHA: .attribute 5, "rv64i2p1_a2p1_zabha1p0"
+; RV64ZABHA: .attribute 5, "rv64i2p1_a2p1_zaamo1p0_zabha1p0"
 ; RV64ZVBC32E: .attribute 5, "rv64i2p1_zicsr2p0_zvbc32e0p7_zve32x1p0_zvl32b1p0"
 ; RV64ZVKGS: .attribute 5, "rv64i2p1_zicsr2p0_zve32x1p0_zvkg1p0_zvkgs0p7_zvl32b1p0"
 ; RV64SSNPM: .attribute 5, "rv64i2p1_ssnpm1p0"
diff --git a/llvm/test/MC/RISCV/attribute-arch.s b/llvm/test/MC/RISCV/attribute-arch.s
index 72a1db865e025d..30cf037b1f70a4 100644
--- a/llvm/test/MC/RISCV/attribute-arch.s
+++ b/llvm/test/MC/RISCV/attribute-arch.s
@@ -394,7 +394,7 @@
 # CHECK: .attribute     5, "rv32i2p1_f2p2_zicsr2p0_zfbfmin1p0_zve32f1p0_zve32x1p0_zvfbfmin1p0_zvfbfwma1p0_zvl32b1p0"
 
 .attribute arch, "rv32ia_zacas1p0"
-# CHECK: attribute      5, "rv32i2p1_a2p1_zacas1p0"
+# CHECK: attribute      5, "rv32i2p1_a2p1_zaamo1p0_zacas1p0"
 
 .attribute arch, "rv32izalasr0p1"
 # CHECK: attribute      5, "rv32i2p1_zalasr0p1"
diff --git a/llvm/unittests/TargetParser/RISCVISAInfoTest.cpp b/llvm/unittests/TargetParser/RISCVISAInfoTest.cpp
index 09c0f4159cc7ee..08944659d78f46 100644
--- a/llvm/unittests/TargetParser/RISCVISAInfoTest.cpp
+++ b/llvm/unittests/TargetParser/RISCVISAInfoTest.cpp
@@ -660,16 +660,6 @@ TEST(ParseArchString, MissingDepency) {
     EXPECT_EQ(toString(RISCVISAInfo::parseArchString(Input, true).takeError()),
               "");
   }
-
-  for (StringRef Input : {"rv32i_zacas1p0"}) {
-    EXPECT_EQ(toString(RISCVISAInfo::parseArchString(Input, true).takeError()),
-              "'zacas' requires 'a' or 'zaamo' extension to also be specified");
-  }
-
-  for (StringRef Input : {"rv32i_zabha"}) {
-    EXPECT_EQ(toString(RISCVISAInfo::parseArchString(Input, true).takeError()),
-              "'zabha' requires 'a' or 'zaamo' extension to also be specified");
-  }
 }
 
 TEST(ParseArchString, RejectsUnrecognizedProfileNames) {

[wangpc-pp]

LGTM.
IIUC, there should be no compatibility issue since both of these two extensions are new?

[michaelmaitland]

There was some related discussion at rust-lang/rust#130877 (comment). Will this cause a problem with compatibility with older versions of binutils?

[topperc]

LGTM. IIUC, there should be no compatibility issue since both of these two extensions are new?

Zabha was added to binutils 8 months ago. Zaamo was added 6 months ago. Zacas was added 5 months ago. So its safe to make Zacas depend on Zaamo. Not sure if there was a binutils release between Zaamo and Zabha.

[tclin914]

Zabha and Zacas were supported from binutils 2.43 (the latest release) and there wasn't a binutils release between them.
In binutils 2.43, Zabha/Zacas imply A and A implies Zaamo and Zalrsc. So that we can say Zabha/Zacas also imply Zaamo.
Zabha/Zacas have been fixed to imply Zaamo instead of A by https://patchwork.sourceware.org/project/binutils/patch/[email protected]/ in master branch last month.

The experiment I made with binutils 2.43:
$ riscv64-unknown-elf-clang -march=rv64izabha main.c -S -o main.s
$ cat main.s
...
.attribute 5, "rv64i2p1_zaamo1p0_zabha1p0"
...
$ riscv64-unknown-elf-as main.s -o main.o
$ riscv64-unknown-elf-readelf -A main.o
...
Tag_RISCV_arch: "rv64i2p1_a2p1_zaamo1p0_zabha1p0_zalrsc1p0"

[topperc]

LGTM