guiand updated this revision to Diff 273456.
guiand retitled this revision from "Introduce frozen attribute at call sites
for stricter poison analysis" to "Introduce noundef attribute at call sites for
stricter poison analysis".
guiand edited the summary of this revision.
guiand added a comment.
Renamed to noundef, added additional checks before determining attribute
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D81678/new/
https://reviews.llvm.org/D81678
Files:
clang/include/clang/Basic/CodeGenOptions.def
clang/include/clang/Driver/CC1Options.td
clang/lib/CodeGen/CGCall.cpp
clang/lib/Frontend/CompilerInvocation.cpp
llvm/include/llvm/Bitcode/LLVMBitCodes.h
llvm/include/llvm/IR/Attributes.td
llvm/lib/AsmParser/LLLexer.cpp
llvm/lib/AsmParser/LLParser.cpp
llvm/lib/AsmParser/LLToken.h
llvm/lib/Bitcode/Reader/BitcodeReader.cpp
llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
llvm/lib/IR/Attributes.cpp
llvm/lib/Transforms/Utils/CodeExtractor.cpp
Index: llvm/lib/Transforms/Utils/CodeExtractor.cpp
===================================================================
--- llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -929,6 +929,7 @@
case Attribute::StrictFP:
case Attribute::UWTable:
case Attribute::NoCfCheck:
+ case Attribute::NoUndef:
break;
}
Index: llvm/lib/IR/Attributes.cpp
===================================================================
--- llvm/lib/IR/Attributes.cpp
+++ llvm/lib/IR/Attributes.cpp
@@ -443,6 +443,8 @@
return "cold";
if (hasAttribute(Attribute::ImmArg))
return "immarg";
+ if (hasAttribute(Attribute::NoUndef))
+ return "noundef";
if (hasAttribute(Attribute::ByVal)) {
std::string Result;
Index: llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -731,6 +731,8 @@
return bitc::ATTR_KIND_SANITIZE_MEMTAG;
case Attribute::Preallocated:
return bitc::ATTR_KIND_PREALLOCATED;
+ case Attribute::NoUndef:
+ return bitc::ATTR_KIND_NOUNDEF;
case Attribute::EndAttrKinds:
llvm_unreachable("Can not encode end-attribute kinds marker.");
case Attribute::None:
Index: llvm/lib/Bitcode/Reader/BitcodeReader.cpp
===================================================================
--- llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1532,6 +1532,8 @@
return Attribute::SanitizeMemTag;
case bitc::ATTR_KIND_PREALLOCATED:
return Attribute::Preallocated;
+ case bitc::ATTR_KIND_NOUNDEF:
+ return Attribute::NoUndef;
}
}
Index: llvm/lib/AsmParser/LLToken.h
===================================================================
--- llvm/lib/AsmParser/LLToken.h
+++ llvm/lib/AsmParser/LLToken.h
@@ -196,6 +196,7 @@
kw_naked,
kw_nest,
kw_noalias,
+ kw_noundef,
kw_nobuiltin,
kw_nocapture,
kw_noduplicate,
Index: llvm/lib/AsmParser/LLParser.cpp
===================================================================
--- llvm/lib/AsmParser/LLParser.cpp
+++ llvm/lib/AsmParser/LLParser.cpp
@@ -1374,6 +1374,7 @@
case lltok::kw_inalloca:
case lltok::kw_nest:
case lltok::kw_noalias:
+ case lltok::kw_noundef:
case lltok::kw_nocapture:
case lltok::kw_nonnull:
case lltok::kw_returned:
@@ -1677,6 +1678,9 @@
case lltok::kw_inalloca: B.addAttribute(Attribute::InAlloca); break;
case lltok::kw_inreg: B.addAttribute(Attribute::InReg); break;
case lltok::kw_nest: B.addAttribute(Attribute::Nest); break;
+ case lltok::kw_noundef:
+ B.addAttribute(Attribute::NoUndef);
+ break;
case lltok::kw_noalias: B.addAttribute(Attribute::NoAlias); break;
case lltok::kw_nocapture: B.addAttribute(Attribute::NoCapture); break;
case lltok::kw_nofree: B.addAttribute(Attribute::NoFree); break;
@@ -1774,6 +1778,9 @@
}
case lltok::kw_inreg: B.addAttribute(Attribute::InReg); break;
case lltok::kw_noalias: B.addAttribute(Attribute::NoAlias); break;
+ case lltok::kw_noundef:
+ B.addAttribute(Attribute::NoUndef);
+ break;
case lltok::kw_nonnull: B.addAttribute(Attribute::NonNull); break;
case lltok::kw_signext: B.addAttribute(Attribute::SExt); break;
case lltok::kw_zeroext: B.addAttribute(Attribute::ZExt); break;
Index: llvm/lib/AsmParser/LLLexer.cpp
===================================================================
--- llvm/lib/AsmParser/LLLexer.cpp
+++ llvm/lib/AsmParser/LLLexer.cpp
@@ -696,6 +696,7 @@
KEYWORD(writeonly);
KEYWORD(zeroext);
KEYWORD(immarg);
+ KEYWORD(noundef);
KEYWORD(type);
KEYWORD(opaque);
Index: llvm/include/llvm/IR/Attributes.td
===================================================================
--- llvm/include/llvm/IR/Attributes.td
+++ llvm/include/llvm/IR/Attributes.td
@@ -39,6 +39,9 @@
/// Pass structure by value.
def ByVal : TypeAttr<"byval">;
+/// Parameter or return value may not contain uninitialized or poison bits
+def NoUndef : EnumAttr<"noundef">;
+
/// Marks function as being in a cold path.
def Cold : EnumAttr<"cold">;
Index: llvm/include/llvm/Bitcode/LLVMBitCodes.h
===================================================================
--- llvm/include/llvm/Bitcode/LLVMBitCodes.h
+++ llvm/include/llvm/Bitcode/LLVMBitCodes.h
@@ -643,6 +643,7 @@
ATTR_KIND_PREALLOCATED = 65,
ATTR_KIND_NO_MERGE = 66,
ATTR_KIND_NULL_POINTER_IS_VALID = 67,
+ ATTR_KIND_NOUNDEF = 68,
};
enum ComdatSelectionKindCodes {
Index: clang/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- clang/lib/Frontend/CompilerInvocation.cpp
+++ clang/lib/Frontend/CompilerInvocation.cpp
@@ -888,6 +888,7 @@
Opts.DisableFree = Args.hasArg(OPT_disable_free);
Opts.DiscardValueNames = Args.hasArg(OPT_discard_value_names);
+ Opts.DisableNoundefArgs = Args.hasArg(OPT_disable_noundef_args);
Opts.DisableTailCalls = Args.hasArg(OPT_mdisable_tail_calls);
Opts.NoEscapingBlockTailCalls =
Args.hasArg(OPT_fno_escaping_block_tail_calls);
Index: clang/lib/CodeGen/CGCall.cpp
===================================================================
--- clang/lib/CodeGen/CGCall.cpp
+++ clang/lib/CodeGen/CGCall.cpp
@@ -1877,6 +1877,18 @@
llvm::for_each(NBA->builtinNames(), AddNoBuiltinAttr);
}
+static bool DetermineNoUndef(llvm::Type *Ty, const llvm::DataLayout &DL, const ABIArgInfo &AI) {
+ if (AI.getKind() == ABIArgInfo::Indirect)
+ return false;
+ if (!DL.typeSizeEqualsStoreSize(Ty) && AI.getKind() != ABIArgInfo::Extend)
+ return false;
+ if (Ty->isFloatingPointTy() || Ty->isIntegerTy() || Ty->isPointerTy())
+ return true;
+ if (Ty->isVectorTy())
+ return DL.typeSizeEqualsStoreSize(Ty->getScalarType());
+ return false;
+}
+
/// Construct the IR attribute list of a function or call.
///
/// When adding an attribute, please consider where it should be handled:
@@ -2076,6 +2088,13 @@
QualType RetTy = FI.getReturnType();
const ABIArgInfo &RetAI = FI.getReturnInfo();
+ const llvm::DataLayout &DL = getDataLayout();
+
+ // Determine if the return type could be partially undef
+ if (DetermineNoUndef(getTypes().ConvertTypeForMem(RetTy), DL, RetAI)) {
+ RetAttrs.addAttribute(llvm::Attribute::NoUndef);
+ }
+
switch (RetAI.getKind()) {
case ABIArgInfo::Extend:
if (RetAI.isSignExt())
@@ -2161,6 +2180,12 @@
}
}
+ // Decide whether the argument we're handling could be partially undef
+ bool ArgNoUndef = DetermineNoUndef(getTypes().ConvertTypeForMem(ParamType), DL, AI);
+ if (!CodeGenOpts.DisableNoundefArgs && ArgNoUndef) {
+ Attrs.addAttribute(llvm::Attribute::NoUndef);
+ }
+
// 'restrict' -> 'noalias' is done in EmitFunctionProlog when we
// have the corresponding parameter variable. It doesn't make
// sense to do it here because parameters are so messed up.
Index: clang/include/clang/Driver/CC1Options.td
===================================================================
--- clang/include/clang/Driver/CC1Options.td
+++ clang/include/clang/Driver/CC1Options.td
@@ -503,6 +503,8 @@
HelpText<"Disable freeing of memory on exit">;
def discard_value_names : Flag<["-"], "discard-value-names">,
HelpText<"Discard value names in LLVM IR">;
+def disable_noundef_args : Flag<["-"], "disable-noundef-args">,
+ HelpText<"Disable emitting noundef attribute in LLVM IR">;
def load : Separate<["-"], "load">, MetaVarName<"<dsopath>">,
HelpText<"Load the named plugin (dynamic shared object)">;
def plugin : Separate<["-"], "plugin">, MetaVarName<"<name>">,
Index: clang/include/clang/Basic/CodeGenOptions.def
===================================================================
--- clang/include/clang/Basic/CodeGenOptions.def
+++ clang/include/clang/Basic/CodeGenOptions.def
@@ -52,6 +52,7 @@
CODEGENOPT(DisableFree , 1, 0) ///< Don't free memory.
CODEGENOPT(DiscardValueNames , 1, 0) ///< Discard Value Names from the IR (LLVMContext flag)
+CODEGENOPT(DisableNoundefArgs , 1, 0) ///< Disable emitting `noundef` attributes on IR call arguments
CODEGENOPT(DisableGCov , 1, 0) ///< Don't run the GCov pass, for testing.
CODEGENOPT(DisableLLVMPasses , 1, 0) ///< Don't run any LLVM IR passes to get
///< the pristine IR generated by the
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