[RISCV][MC] MC layer support for the experimental zalasr extension #69685

mehnadnerd · 2023-10-20T07:37:55Z

This PR implements the RISC-V Atomic Load-Acquire and Store-Release Extension (Zalasr).
See also https://github.com/mehnadnerd/riscv-zalasr.

dtcxzyw

Please add some regression tests:

clang/test/Preprocessor/riscv-target-features.c
llvm/test/CodeGen/RISCV/attributes.ll
llvm/test/MC/RISCV/attribute-arch.s
llvm/test/MC/RISCV/zalasr-valid.s
llvm/test/MC/RISCV/zalasr-invalid.s

See also https://reviews.llvm.org/D149248.

llvmbot · 2023-10-20T09:32:23Z

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

@llvm/pr-subscribers-llvm-support

Author: Brendan Sweeney (mehnadnerd)

Changes

This PR implements the RISC-V Atomic Load-Acquire and Store-Release Extension (Zalasr).
See also https://github.com/mehnadnerd/riscv-zalasr.

Full diff: https://github.com/llvm/llvm-project/pull/69685.diff

6 Files Affected:

(modified) llvm/docs/RISCVUsage.rst (+3)
(modified) llvm/lib/Support/RISCVISAInfo.cpp (+1)
(modified) llvm/lib/Target/RISCV/RISCVFeatures.td (+7)
(modified) llvm/lib/Target/RISCV/RISCVInstrInfo.td (+1)
(added) llvm/lib/Target/RISCV/RISCVInstrInfoZalasr.td (+66)
(modified) llvm/unittests/Support/RISCVISAInfoTest.cpp (+1)

diff --git a/llvm/docs/RISCVUsage.rst b/llvm/docs/RISCVUsage.rst
index 6812efaeb36e0c1..f9a7d4633e0a8dc 100644
--- a/llvm/docs/RISCVUsage.rst
+++ b/llvm/docs/RISCVUsage.rst
@@ -197,6 +197,9 @@ The primary goal of experimental support is to assist in the process of ratifica
 ``experimental-zacas``
   LLVM implements the `1.0-rc1 draft specification <https://github.com/riscv/riscv-zacas/releases/tag/v1.0-rc1>`_.
 
+``experimental-zalasr``
+  LLVM implements the `most recent specification <https://github.com/mehnadnerd/riscv-zalasr>`_.
+
 ``experimental-zfbfmin``, ``experimental-zvfbfmin``, ``experimental-zvfbfwma``
   LLVM implements assembler support for the `0.8.0 draft specification <https://github.com/riscv/riscv-bfloat16/releases/tag/20230629>`_.
 
diff --git a/llvm/lib/Support/RISCVISAInfo.cpp b/llvm/lib/Support/RISCVISAInfo.cpp
index 22208e2e0c2950b..847a2c6f37656ba 100644
--- a/llvm/lib/Support/RISCVISAInfo.cpp
+++ b/llvm/lib/Support/RISCVISAInfo.cpp
@@ -168,6 +168,7 @@ static const RISCVSupportedExtension SupportedExperimentalExtensions[] = {
     {"ssaia", RISCVExtensionVersion{1, 0}},
 
     {"zacas", RISCVExtensionVersion{1, 0}},
+    {"zalasr", RISCVExtensionVersion{1, 0}},
 
     {"zfbfmin", RISCVExtensionVersion{0, 8}},
 
diff --git a/llvm/lib/Target/RISCV/RISCVFeatures.td b/llvm/lib/Target/RISCV/RISCVFeatures.td
index 979bc0ea8c7d065..b011fb4eb4421f0 100644
--- a/llvm/lib/Target/RISCV/RISCVFeatures.td
+++ b/llvm/lib/Target/RISCV/RISCVFeatures.td
@@ -708,6 +708,13 @@ def HasStdExtZacas : Predicate<"Subtarget->hasStdExtZacas()">,
                                AssemblerPredicate<(all_of FeatureStdExtZacas),
                                "'Zacas' (Atomic Compare-And-Swap Instructions)">;
 
+def FeatureStdExtZalasr
+    : SubtargetFeature<"experimental-zalasr", "HasStdExtZalasr", "true",
+                       "'Zalasr' (Load-Acquire and Store-Release Instructions)">;
+def HasStdExtZalasr : Predicate<"Subtarget->hasStdExtZalasr()">,
+                               AssemblerPredicate<(all_of FeatureStdExtZalasr),
+                               "'Zalasr' (Load-Acquire and Store-Release Instructions)">;
+
 //===----------------------------------------------------------------------===//
 // Vendor extensions
 //===----------------------------------------------------------------------===//
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.td b/llvm/lib/Target/RISCV/RISCVInstrInfo.td
index 94de559b1e6e037..d4d9c303d25ca06 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.td
@@ -2004,6 +2004,7 @@ include "RISCVInstrInfoM.td"
 
 // Atomic
 include "RISCVInstrInfoA.td"
+include "RISCVInstrInfoZalasr.td"
 
 // Scalar FP
 include "RISCVInstrInfoF.td"
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoZalasr.td b/llvm/lib/Target/RISCV/RISCVInstrInfoZalasr.td
new file mode 100644
index 000000000000000..cb603bb60306295
--- /dev/null
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoZalasr.td
@@ -0,0 +1,66 @@
+//===-- RISCVInstrInfoZalasr.td - RISC-V 'Zalasr' instructions -------*- tablegen -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file describes the RISC-V instructions from the Zalasr (Load-Acquire
+// and Store-Release) extension
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+// Instruction class templates
+//===----------------------------------------------------------------------===//
+
+let hasSideEffects = 0, mayLoad = 1, mayStore = 0 in
+class LAQ_r<bit aq, bit rl, bits<3> funct3, string opcodestr>
+    : RVInstRAtomic<0b00110, aq, rl, funct3, OPC_AMO,
+                    (outs GPR:$rd), (ins GPRMemZeroOffset:$rs1),
+                    opcodestr, "$rd, $rs1"> {
+  let rs2 = 0;
+}
+
+let hasSideEffects = 0, mayLoad = 0, mayStore = 1 in
+class SRL_r<bit aq, bit rl, bits<3> funct3, string opcodestr>
+    : RVInstRAtomic<0b00111, aq, rl, funct3, OPC_AMO,
+                    (outs ), (ins GPRMemZeroOffset:$rs1, GPR:$rs2),
+                    opcodestr, "$rs2, $rs1"> {
+  let rd = 0;
+}
+multiclass LAQ_r_aq_rl<bits<3> funct3, string opcodestr> {
+  def _AQ    : LAQ_r<1, 0, funct3, opcodestr # ".aq">;
+  def _AQ_RL : LAQ_r<1, 1, funct3, opcodestr # ".aqrl">;
+}
+
+multiclass SRL_r_aq_rl<bits<3> funct3, string opcodestr> {
+  def _RL    : SRL_r<0, 1, funct3, opcodestr # ".rl">;
+  def _AQ_RL : SRL_r<1, 1, funct3, opcodestr # ".aqrl">;
+}
+
+//===----------------------------------------------------------------------===//
+// Instructions
+//===----------------------------------------------------------------------===//
+
+
+let Predicates = [HasStdExtZalasr] in {
+defm LB_AQ : LAQ_r_aq_rl<0b000, "lb">;
+defm LH_AQ : LAQ_r_aq_rl<0b001, "lh">;
+defm LW_AQ : LAQ_r_aq_rl<0b010, "lw">;
+defm SB_RL : SRL_r_aq_rl<0b000, "sb">;
+defm SH_RL : SRL_r_aq_rl<0b001, "sh">;
+defm SW_RL : SRL_r_aq_rl<0b010, "sw">;
+} // Predicates = [HasStdExtZalasr]
+
+let Predicates = [HasStdExtZalasr, IsRV64] in {
+defm LD_AQ : LAQ_r_aq_rl<0b011, "ld">;
+defm SD_RL : SRL_r_aq_rl<0b011, "sd">;
+} // Predicates = [HasStdExtZalasr, IsRV64]
+
+//===----------------------------------------------------------------------===//
+// Pseudo-instructions and codegen patterns
+//===----------------------------------------------------------------------===//
+
+// Future work: Work out mapping with leading/trailing fences, &c
diff --git a/llvm/unittests/Support/RISCVISAInfoTest.cpp b/llvm/unittests/Support/RISCVISAInfoTest.cpp
index 885ec88f8f697d0..ae599991d7a6d81 100644
--- a/llvm/unittests/Support/RISCVISAInfoTest.cpp
+++ b/llvm/unittests/Support/RISCVISAInfoTest.cpp
@@ -733,6 +733,7 @@ Experimental extensions
     zicfilp             0.2       This is a long dummy description
     zicond              1.0
     zacas               1.0
+    zalasr              1.0
     zfbfmin             0.8
     ztso                0.1
     zvbb                1.0

asb · 2023-10-20T10:07:23Z

Zalasr is using the namespace reserved for standard extensions, but doesn't seem to be being developed under github.com/riscv - why is that? Is the repo going to get moved to that org? I see it is an official in-development extension based on your riscv-opcodes PR, but it would be great to remove that ambiguity.

wangpc-pp · 2023-10-20T10:16:14Z

If we are going to support Zalasr, can we consider #67108 too?

mehnadnerd · 2023-10-20T18:48:04Z

Zalasr is using the namespace reserved for standard extensions, but doesn't seem to be being developed under github.com/riscv - why is that? Is the repo going to get moved to that org? I see it is an official in-development extension based on your riscv-opcodes PR, but it would be great to remove that ambiguity.

I'm honestly not entirely sure--I think it will be moved into there eventually, but I am unsure of the process.

mehnadnerd · 2023-10-20T22:48:45Z

I've updated it to add regression tests.

github-actions · 2023-12-18T20:18:29Z

✅ With the latest revision this PR passed the C/C++ code formatter.

… though

topperc · 2024-01-25T22:56:51Z

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

+    const Instruction *I) const {
+  if (Subtarget.hasStdExtZalasr()) {
+    return false;
+  } else {


No else after return

…o longer used in the lowering)

mehnadnerd · 2024-01-25T23:03:54Z

Still needs tests for the lowering.

topperc · 2024-01-25T22:57:34Z

llvm/lib/Target/RISCV/RISCVInstrInfoA.td

+  let IsAtomicOrderingSequentiallyConsistent = 1;
+}
+
+// An atomic store operation that doesn't actually need to be atomic on RISCV.


RISCV -> RISC-V

topperc · 2024-01-25T23:03:33Z

llvm/lib/Target/RISCV/RISCVInstrInfoA.td

-  def : LdPat<atomic_load_8,  LB>;
-  def : LdPat<atomic_load_16, LH>;
-  def : LdPat<atomic_load_32, LW>;
+  def : LdPat<relaxed_load<atomic_load_8>,  LB>;


If this is an MC patch as the title says, we shouldn't be touching any isel patterns.

This was originally an MC patch but I am adding isel support as well. What should I change the title to?

We usually want MC and CodeGen changes as separate PRs.

Oh. I will separate it out then.

topperc · 2024-01-25T23:05:52Z

clang/test/Preprocessor/riscv-target-features.c

@@ -1120,6 +1121,14 @@
 // RUN:   -o - | FileCheck --check-prefix=CHECK-SMEPMP-EXT %s
 // CHECK-SMEPMP-EXT: __riscv_smepmp  1000000{{$}}

+// RUN: %clang --target=riscv32 -menable-experimental-extensions \
+// RUN: -march=rv32i_zalasr1p0 -x c -E -dM %s \


Indent line continuations 2 spaces and drop -x c. This was recently updated in the reset of the file.

topperc · 2024-01-25T23:06:59Z

llvm/docs/RISCVUsage.rst

@@ -228,6 +228,9 @@ The primary goal of experimental support is to assist in the process of ratifica
 ``experimental-zacas``
  LLVM implements the `1.0-rc1 draft specification <https://github.com/riscv/riscv-zacas/releases/tag/v1.0-rc1>`_.

+``experimental-zalasr``
+  LLVM implements the `most recent specification <https://github.com/mehnadnerd/riscv-zalasr>`_.


Can we nail this down to a version or a date? "most recent" is wrong if that repo changes.

topperc · 2024-01-25T23:07:32Z

llvm/lib/Target/RISCV/RISCVFeatures.td

+    : SubtargetFeature<"experimental-zalasr", "HasStdExtZalasr", "true",
+                       "'Zalasr' (Load-Acquire and Store-Release Instructions)">;
+def HasStdExtZalasr : Predicate<"Subtarget->hasStdExtZalasr()">,
+                               AssemblerPredicate<(all_of FeatureStdExtZalasr),


Align AssemblerPredicate with Predicate on the previous line. This file was recently reformatted.

topperc · 2024-01-25T23:08:12Z

llvm/lib/Target/RISCV/RISCVInstrInfoZalasr.td

+// Pseudo-instructions and codegen patterns
+//===----------------------------------------------------------------------===//
+
+class PatLAQ<SDPatternOperator OpNode, RVInst Inst, ValueType vt = XLenVT>


Don't add patterns in MC patch.

mehnadnerd · 2024-01-29T23:15:50Z

Closing because superseded by #79911.

llvmbot added backend:RISC-V llvm:support labels Oct 20, 2023

dtcxzyw changed the title ~~[RISCV] Support for the RISCV Zalasr extension (at least at the assembly level)~~ [RISCV][MC] MC layer support for the experimental zalasr extension Oct 20, 2023

dtcxzyw requested review from topperc and asb October 20, 2023 09:16

dtcxzyw requested changes Oct 20, 2023

View reviewed changes

asb mentioned this pull request Oct 20, 2023

[RISCV] Select atomic_{load/store} to pseudos and expand them later #67108

Open

mehnadnerd force-pushed the main branch from 5df0aeb to d412fa8 Compare October 20, 2023 22:46

llvmbot added clang Clang issues not falling into any other category mc Machine (object) code labels Oct 20, 2023

mehnadnerd force-pushed the main branch from d412fa8 to 89b78a0 Compare December 18, 2023 20:15

brs added 2 commits January 25, 2024 16:47

[RISCV][MC] MC layer support for the experimental zalasr extension

c5ade18

Adding isel lowering for Zalasr. Not sure if is matches the psABI yet…

5cd0279

… though

mehnadnerd force-pushed the main branch 2 times, most recently from cbc1df5 to 25115f9 Compare January 25, 2024 22:55

topperc reviewed Jan 25, 2024

View reviewed changes

Making Zalasr lowering match the psABI (aka lb.aqrl and sb.aqrl are n…

b41f305

…o longer used in the lowering)

mehnadnerd force-pushed the main branch from 25115f9 to b41f305 Compare January 25, 2024 23:02

topperc reviewed Jan 25, 2024

View reviewed changes

mehnadnerd mentioned this pull request Jan 29, 2024

[RISCV][MC] MC layer support for the experimental zalasr extension #79911

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[RISCV][MC] MC layer support for the experimental zalasr extension #69685

[RISCV][MC] MC layer support for the experimental zalasr extension #69685

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