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

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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253550 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/IPO/FunctionAttrs.cpp b/lib/Transforms/IPO/FunctionAttrs.cpp
index 8a697c3e6afc4d9bffb1a0c61c8ecb4c7024d355..e699c5e0df5cf100581e5dba163b486b2b0c8e10 100644 (file)
--- a/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -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);
   }
 

diff --git a/test/Transforms/FunctionAttrs/forced.ll b/test/Transforms/FunctionAttrs/forced.ll
new file mode 100644 (file)
index 0000000..d0bdb15
--- /dev/null
+++ b/test/Transforms/FunctionAttrs/forced.ll
@@ -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 }