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[FunctionAttrs] Provide a mechanism for adding function attributes from the command line 

This provides a way to force a function to have certain attributes from the command line. This can be useful when debugging or doing workload exploration, where manually editing IR is tedious or not possible (due to build systems etc).

The syntax is -force-attribute=function_name:attribute_name

All function attributes are parsed except alignstack as it requires an argument.

llvm-svn: 253550
This commit is contained in:
James Molloy 2015-11-19 08:49:57 +00:00
parent dd679b334b
commit 0ecdbe7d6b
2 changed files with 79 additions and 0 deletions
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67
llvm/lib/Transforms/IPO/FunctionAttrs.cpp
View File

@ -23,6 +23,7 @@
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
@ -52,6 +53,13 @@ STATISTIC(NumNonNullReturn, "Number of function returns marked nonnull");
STATISTIC(NumAnnotated, "Number of attributes added to library functions");
STATISTIC(NumNoRecurse, "Number of functions marked as norecurse");
static cl::list<std::string>
ForceAttributes("force-attribute", cl::Hidden,
cl::desc("Add an attribute to a function. This should be a "
"pair of 'function-name:attribute-name', for "
"example -force-add-attribute=foo:noinline. This "
"option can be specified multiple times."));
namespace {
typedef SmallSetVector<Function *, 8> SCCNodeSet;
}
@ -1843,6 +1851,64 @@ static bool addNoRecurseAttrsTopDownOnly(Function *F) {
return false;
}
static Attribute::AttrKind parseAttrKind(StringRef Kind) {
return StringSwitch<Attribute::AttrKind>(Kind)
.Case("alwaysinline", Attribute::AlwaysInline)
.Case("builtin", Attribute::Builtin)
.Case("cold", Attribute::Cold)
.Case("convergent", Attribute::Convergent)
.Case("inlinehint", Attribute::InlineHint)
.Case("jumptable", Attribute::JumpTable)
.Case("minsize", Attribute::MinSize)
.Case("naked", Attribute::Naked)
.Case("nobuiltin", Attribute::NoBuiltin)
.Case("noduplicate", Attribute::NoDuplicate)
.Case("noimplicitfloat", Attribute::NoImplicitFloat)
.Case("noinline", Attribute::NoInline)
.Case("nonlazybind", Attribute::NonLazyBind)
.Case("noredzone", Attribute::NoRedZone)
.Case("noreturn", Attribute::NoReturn)
.Case("norecurse", Attribute::NoRecurse)
.Case("nounwind", Attribute::NoUnwind)
.Case("optnone", Attribute::OptimizeNone)
.Case("optsize", Attribute::OptimizeForSize)
.Case("readnone", Attribute::ReadNone)
.Case("readonly", Attribute::ReadOnly)
.Case("argmemonly", Attribute::ArgMemOnly)
.Case("returns_twice", Attribute::ReturnsTwice)
.Case("safestack", Attribute::SafeStack)
.Case("sanitize_address", Attribute::SanitizeAddress)
.Case("sanitize_memory", Attribute::SanitizeMemory)
.Case("sanitize_thread", Attribute::SanitizeThread)
.Case("ssp", Attribute::StackProtect)
.Case("sspreq", Attribute::StackProtectReq)
.Case("sspstrong", Attribute::StackProtectStrong)
.Case("uwtable", Attribute::UWTable)
.Default(Attribute::None);
}
/// If F has any forced attributes given on the command line, add them.
static bool addForcedAttributes(Function *F) {
bool Changed = false;
for (auto &S : ForceAttributes) {
auto KV = StringRef(S).split(':');
if (KV.first != F->getName())
continue;
auto Kind = parseAttrKind(KV.second);
if (Kind == Attribute::None) {
DEBUG(dbgs() << "ForcedAttribute: " << KV.second
<< " unknown or not handled!\n");
continue;
}
if (F->hasFnAttribute(Kind))
continue;
Changed = true;
F->addFnAttr(Kind);
}
return Changed;
}
bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) {
TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
bool Changed = false;
@ -1878,6 +1944,7 @@ bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) {
if (F->isDeclaration())
Changed |= inferPrototypeAttributes(*F, *TLI);
Changed |= addForcedAttributes(F);
SCCNodes.insert(F);
}

12
llvm/test/Transforms/FunctionAttrs/forced.ll Normal file
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@ -0,0 +1,12 @@
; RUN: opt < %s -S -functionattrs | FileCheck %s --check-prefix=CHECK-CONTROL
; RUN: opt < %s -S -functionattrs -force-attribute foo:noinline | FileCheck %s --check-prefix=CHECK-FOO
; CHECK-CONTROL: define void @foo() #0 {
; CHECK-FOO: define void @foo() #0 {
define void @foo() {
ret void
}
; CHECK-CONTROL: attributes #0 = { norecurse readnone }
; CHECK-FOO: attributes #0 = { noinline norecurse readnone }