GlobalsModRef+OptNone: Don't prove readnone/other properties from an optnone function
Seems like at least one reasonable interpretation of optnone is that the
optimizer never "looks inside" a function. This fix is consistent with
that interpretation.
Specifically this came up in the situation:
f3 calls f2 calls f1
f2 is always_inline
f1 is optnone
The application of readnone to f1 (& thus to f2) caused the inliner to
kill the call to f2 as being trivially dead (without even checking the
cost function, as it happens - not sure if that's also a bug).
llvm-svn: 304833
diff --git a/llvm/lib/Analysis/GlobalsModRef.cpp b/llvm/lib/Analysis/GlobalsModRef.cpp
index 33f00cb..39c3879 100644
--- a/llvm/lib/Analysis/GlobalsModRef.cpp
+++ b/llvm/lib/Analysis/GlobalsModRef.cpp
@@ -475,7 +475,10 @@
const std::vector<CallGraphNode *> &SCC = *I;
assert(!SCC.empty() && "SCC with no functions?");
- if (!SCC[0]->getFunction() || !SCC[0]->getFunction()->isDefinitionExact()) {
+ Function *F = SCC[0]->getFunction();
+
+ if (!F || !F->isDefinitionExact() ||
+ F->hasFnAttribute(Attribute::OptimizeNone)) {
// Calls externally or not exact - can't say anything useful. Remove any
// existing function records (may have been created when scanning
// globals).
@@ -484,13 +487,12 @@
continue;
}
- FunctionInfo &FI = FunctionInfos[SCC[0]->getFunction()];
+ FunctionInfo &FI = FunctionInfos[F];
bool KnowNothing = false;
// Collect the mod/ref properties due to called functions. We only compute
// one mod-ref set.
for (unsigned i = 0, e = SCC.size(); i != e && !KnowNothing; ++i) {
- Function *F = SCC[i]->getFunction();
if (!F) {
KnowNothing = true;
break;
@@ -545,6 +547,15 @@
for (auto *Node : SCC) {
if (FI.getModRefInfo() == MRI_ModRef)
break; // The mod/ref lattice saturates here.
+
+ // Don't prove any properties based on the implementation of an optnone
+ // function.
+ if (Node->getFunction()->hasFnAttribute(Attribute::OptimizeNone)) {
+ FI.addModRefInfo(MRI_Ref);
+ FI.addModRefInfo(MRI_Mod);
+ continue;
+ }
+
for (Instruction &I : instructions(Node->getFunction())) {
if (FI.getModRefInfo() == MRI_ModRef)
break; // The mod/ref lattice saturates here.