[llvm] r253550 - [FunctionAttrs] Provide a mechanism for adding function attributes from the command line

[James Molloy via llvm-commits]

Author: jamesm
Date: Thu Nov 19 02:49:57 2015
New Revision: 253550

URL: http://llvm.org/viewvc/llvm-project?rev=253550&view=rev
Log:
[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.

Added:
    llvm/trunk/test/Transforms/FunctionAttrs/forced.ll
Modified:
    llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp

Modified: llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp?rev=253550&r1=253549&r2=253550&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp Thu Nov 19 02:49:57 2015
@@ -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 f
 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
   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(CallGraphSC
     if (F->isDeclaration())
       Changed |= inferPrototypeAttributes(*F, *TLI);
 
+    Changed |= addForcedAttributes(F);
     SCCNodes.insert(F);
   }
 

Added: llvm/trunk/test/Transforms/FunctionAttrs/forced.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/forced.ll?rev=253550&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/FunctionAttrs/forced.ll (added)
+++ llvm/trunk/test/Transforms/FunctionAttrs/forced.ll Thu Nov 19 02:49:57 2015
@@ -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 }