[llvm] [LLVM][rtsan] Add nonblocking attribute for the realtime sanitizer (PR #100596)
Chris Apple via llvm-commits
llvm-commits at lists.llvm.org
Tue Jul 30 13:12:48 PDT 2024
https://github.com/cjappl updated https://github.com/llvm/llvm-project/pull/100596
>From d314f93a17f68891752f35681d90ee0f47765a32 Mon Sep 17 00:00:00 2001
From: Chris Apple <cja-private at pm.me>
Date: Tue, 30 Jul 2024 12:19:16 -0700
Subject: [PATCH 1/2] [LLVM][rtsan] Add LLVM nonblocking attribute for realtime
sanitizer
---
llvm/include/llvm/Bitcode/LLVMBitCodes.h | 1 +
llvm/include/llvm/IR/Attributes.td | 3 +++
llvm/lib/Bitcode/Reader/BitcodeReader.cpp | 2 ++
llvm/lib/Bitcode/Writer/BitcodeWriter.cpp | 2 ++
llvm/lib/Transforms/Utils/CodeExtractor.cpp | 1 +
llvm/test/Bitcode/attributes.ll | 7 +++++++
llvm/test/Bitcode/compatibility.ll | 8 ++++++--
7 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/llvm/include/llvm/Bitcode/LLVMBitCodes.h b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
index fb88f2fe75adb..61b046c26a97f 100644
--- a/llvm/include/llvm/Bitcode/LLVMBitCodes.h
+++ b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
@@ -758,6 +758,7 @@ enum AttributeKindCodes {
ATTR_KIND_SANITIZE_NUMERICAL_STABILITY = 93,
ATTR_KIND_INITIALIZES = 94,
ATTR_KIND_HYBRID_PATCHABLE = 95,
+ ATTR_KIND_NONBLOCKING = 96,
};
enum ComdatSelectionKindCodes {
diff --git a/llvm/include/llvm/IR/Attributes.td b/llvm/include/llvm/IR/Attributes.td
index e1bd193891c1e..8d90e912f279c 100644
--- a/llvm/include/llvm/IR/Attributes.td
+++ b/llvm/include/llvm/IR/Attributes.td
@@ -239,6 +239,9 @@ def ReadNone : EnumAttr<"readnone", [ParamAttr]>;
/// Function only reads from memory.
def ReadOnly : EnumAttr<"readonly", [ParamAttr]>;
+/// Function is marked to be non-blocking
+def NonBlocking : EnumAttr<"nonblocking", [FnAttr]>;
+
/// Return value is always equal to this argument.
def Returned : EnumAttr<"returned", [ParamAttr]>;
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 84d624f6cf8fa..a519748bc1c83 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -2109,6 +2109,8 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
return Attribute::ReadOnly;
case bitc::ATTR_KIND_RETURNED:
return Attribute::Returned;
+ case bitc::ATTR_KIND_NONBLOCKING:
+ return Attribute::NonBlocking;
case bitc::ATTR_KIND_RETURNS_TWICE:
return Attribute::ReturnsTwice;
case bitc::ATTR_KIND_S_EXT:
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 324dcbca8137e..d54aeae74a59f 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -805,6 +805,8 @@ static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
case Attribute::OptimizeNone:
return bitc::ATTR_KIND_OPTIMIZE_NONE;
+ case Attribute::NonBlocking:
+ return bitc::ATTR_KIND_NONBLOCKING;
case Attribute::ReadNone:
return bitc::ATTR_KIND_READ_NONE;
case Attribute::ReadOnly:
diff --git a/llvm/lib/Transforms/Utils/CodeExtractor.cpp b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
index 5bca5cf8ff91f..1339bbb3842d4 100644
--- a/llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -946,6 +946,7 @@ Function *CodeExtractor::constructFunction(const ValueSet &inputs,
case Attribute::NoUnwind:
case Attribute::NoSanitizeBounds:
case Attribute::NoSanitizeCoverage:
+ case Attribute::NonBlocking:
case Attribute::NullPointerIsValid:
case Attribute::OptimizeForDebugging:
case Attribute::OptForFuzzing:
diff --git a/llvm/test/Bitcode/attributes.ll b/llvm/test/Bitcode/attributes.ll
index f4dc9b9849827..5f8617dad8dfd 100644
--- a/llvm/test/Bitcode/attributes.ll
+++ b/llvm/test/Bitcode/attributes.ll
@@ -505,6 +505,12 @@ define void @f86() nosanitize_bounds
ret void;
}
+; CHECK: define void @f92() #53
+define void @f92() nonblocking
+{
+ ret void;
+}
+
; CHECK: define void @f87() [[FNRETTHUNKEXTERN:#[0-9]+]]
define void @f87() fn_ret_thunk_extern { ret void }
@@ -599,6 +605,7 @@ define void @initializes(ptr initializes((-4, 0), (4, 8)) %a) {
; CHECK: attributes #50 = { disable_sanitizer_instrumentation }
; CHECK: attributes #51 = { uwtable(sync) }
; CHECK: attributes #52 = { nosanitize_bounds }
+; CHECK: attributes #53 = { nonblocking }
; CHECK: attributes [[FNRETTHUNKEXTERN]] = { fn_ret_thunk_extern }
; CHECK: attributes [[SKIPPROFILE]] = { skipprofile }
; CHECK: attributes [[OPTDEBUG]] = { optdebug }
diff --git a/llvm/test/Bitcode/compatibility.ll b/llvm/test/Bitcode/compatibility.ll
index e437c37d8d1c8..1471138b91a9f 100644
--- a/llvm/test/Bitcode/compatibility.ll
+++ b/llvm/test/Bitcode/compatibility.ll
@@ -1564,7 +1564,7 @@ exit:
; CHECK: select <2 x i1> <i1 true, i1 false>, <2 x i8> <i8 2, i8 3>, <2 x i8> <i8 3, i8 2>
call void @f.nobuiltin() builtin
- ; CHECK: call void @f.nobuiltin() #52
+ ; CHECK: call void @f.nobuiltin() #53
call fastcc noalias ptr @f.noalias() noinline
; CHECK: call fastcc noalias ptr @f.noalias() #12
@@ -1991,6 +1991,9 @@ declare void @f.allockind() allockind("alloc,uninitialized")
declare void @f.sanitize_numerical_stability() sanitize_numerical_stability
; CHECK: declare void @f.sanitize_numerical_stability() #51
+declare void @f.nonblocking() nonblocking
+; CHECK: declare void @f.nonblocking() #52
+
; CHECK: declare nofpclass(snan) float @nofpclass_snan(float nofpclass(snan))
declare nofpclass(snan) float @nofpclass_snan(float nofpclass(snan))
@@ -2113,7 +2116,8 @@ define float @nofpclass_callsites(float %arg) {
; CHECK: attributes #49 = { nosanitize_bounds }
; CHECK: attributes #50 = { allockind("alloc,uninitialized") }
; CHECK: attributes #51 = { sanitize_numerical_stability }
-; CHECK: attributes #52 = { builtin }
+; CHECK: attributes #52 = { nonblocking }
+; CHECK: attributes #53 = { builtin }
;; Metadata
>From 7ad6ea4c4e8a557e06a056164521cf7aacfb8448 Mon Sep 17 00:00:00 2001
From: Chris Apple <cja-private at pm.me>
Date: Tue, 30 Jul 2024 13:12:36 -0700
Subject: [PATCH 2/2] [PR] Add langref docs
---
llvm/docs/LangRef.rst | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index cd86156ec816f..7fbd6dd4ed8f2 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -2120,6 +2120,12 @@ example:
making stack traces less useful for debugging. This attribute gives the
user control over the tradeoff between code size and debug information
precision.
+``nonblocking``
+ This attribute indicates that a function should not block and should only
+ call other non-blocking functions. Such functions are often subject to
+ "real-time constraints", operate on a fixed deadline, and must not call
+ blocking functions such as malloc, free, or syscalls. RealtimeSanitizer
+ utilizes this attribute to catch real-time safety violations at runtime.
``nonlazybind``
This attribute suppresses lazy symbol binding for the function. This
may make calls to the function faster, at the cost of extra program
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