[optnone] Make the optnone attribute effective at suppressing function
attribute and function argument attribute synthesizing and propagating.
As with the other uses of this attribute, the goal remains a best-effort
(no guarantees) attempt to not optimize the function or assume things
about the function when optimizing. This is particularly useful for
compiler testing, bisecting miscompiles, triaging things, etc. I was
hitting specific issues using optnone to isolate test code from a test
driver for my fuzz testing, and this is one step of fixing that.
llvm-svn: 215538
diff --git a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
index 5299e64..7e0cfa9 100644
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -161,8 +161,9 @@
for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
Function *F = (*I)->getFunction();
- if (!F)
- // External node - may write memory. Just give up.
+ if (!F || F->hasFnAttribute(Attribute::OptimizeNone))
+ // External node or node we don't want to optimize - assume it may write
+ // memory and give up.
return false;
AliasAnalysis::ModRefBehavior MRB = AA->getModRefBehavior(F);
@@ -527,7 +528,8 @@
// looking up whether a given CallGraphNode is in this SCC.
for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
Function *F = (*I)->getFunction();
- if (F && !F->isDeclaration() && !F->mayBeOverridden())
+ if (F && !F->isDeclaration() && !F->mayBeOverridden() &&
+ !F->hasFnAttribute(Attribute::OptimizeNone))
SCCNodes.insert(F);
}
@@ -541,8 +543,9 @@
for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
Function *F = (*I)->getFunction();
- if (!F)
- // External node - only a problem for arguments that we pass to it.
+ if (!F || F->hasFnAttribute(Attribute::OptimizeNone))
+ // External node or function we're trying not to optimize - only a problem
+ // for arguments that we pass to it.
continue;
// Definitions with weak linkage may be overridden at linktime with
@@ -794,8 +797,8 @@
for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
Function *F = (*I)->getFunction();
- if (!F)
- // External node - skip it;
+ if (!F || F->hasFnAttribute(Attribute::OptimizeNone))
+ // External node or node we don't want to optimize - skip it;
return false;
// Already noalias.
@@ -834,6 +837,9 @@
/// given function and set any applicable attributes. Returns true
/// if any attributes were set and false otherwise.
bool FunctionAttrs::inferPrototypeAttributes(Function &F) {
+ if (F.hasFnAttribute(Attribute::OptimizeNone))
+ return false;
+
FunctionType *FTy = F.getFunctionType();
LibFunc::Func TheLibFunc;
if (!(TLI->getLibFunc(F.getName(), TheLibFunc) && TLI->has(TheLibFunc)))