llvm-reduce: Reduce prefix data

[arsenm]

Summary

Also fixes broken cloning.

[regehr]

omg thank you, the cloning bug(s) have been bothering me for a long time

[arsenm]

In D140865#4022340, @regehr wrote:

omg thank you, the cloning bug(s) have been bothering me for a long time

There are actual users of prefix data?

[regehr]

ok the llvm-reduce change looks clearly good. I'm not the right person to look at the other part

I only meant that I run into bugs in CloneModule almost every time I try to use it for something, and they're a real pain to track down!!

[nikic]

LG

[arsenm]

4afb10d572ead76b033c72195f6d280014e04ccc

llvm/lib/Transforms/Utils/CloneFunction.cpp

#endif
 
   // Fix up the personality function that got copied over.
   if (OldFunc->hasPersonalityFn())
     NewFunc->setPersonalityFn(
         MapValue(OldFunc->getPersonalityFn(), VMap,
                  ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
                  TypeMapper, Materializer));
 
+  if (OldFunc->hasPrefixData()) {
+    NewFunc->setPrefixData(
+        MapValue(OldFunc->getPrefixData(), VMap,
+                 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
+                 TypeMapper, Materializer));
+  }
+
   SmallVector<AttributeSet, 4> NewArgAttrs(NewFunc->arg_size());
   AttributeList OldAttrs = OldFunc->getAttributes();
 
   // Clone any argument attributes that are present in the VMap.
   for (const Argument &OldArg : OldFunc->args()) {
     if (Argument *NewArg = dyn_cast<Argument>(VMap[&OldArg])) {
       NewArgAttrs[NewArg->getArgNo()] =
           OldAttrs.getParamAttrs(OldArg.getArgNo());

llvm/test/tools/llvm-reduce/reduce-prefix-data.ll

+; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=function-data --test FileCheck --test-arg --check-prefix=CHECK --test-arg %s --test-arg --input-file %s -o %t
+; RUN: FileCheck -check-prefixes=CHECK,RESULT %s < %t
+
+@gv = linkonce_odr global i32 1
+
+; CHECK: define void @drop_prefix_i32_const()
+define void @drop_prefix_i32_const() prefix i32 1 {
+  ret void
+}
+
+; CHECK: define void @keep_prefix_i32_const() prefix i32 1 {
+define void @keep_prefix_i32_const() prefix i32 1 {
+  ret void
+}
+
+; CHECK: define void @drop_prefix_ptr_global()
+define void @drop_prefix_ptr_global() prefix ptr @gv {
+  ret void
+}
+
+; CHECK: define void @keep_prefix_ptr_global() prefix ptr @gv {
+define void @keep_prefix_ptr_global() prefix ptr @gv {
+  ret void
+}
+
+; Make sure there's no invalid reduction if the prefix data is really
+; accessed
+; CHECK: define i32 @drop_uses_prefix_i32_const()
+define i32 @drop_uses_prefix_i32_const() prefix i32 1 {
+  %gep = getelementptr inbounds i32, ptr @drop_uses_prefix_i32_const, i32 -1
+  %load = load i32, ptr %gep
+  ret i32 %load
+}
+
+; CHECK: define ptr @drop_uses_prefix_gv(
+define ptr @drop_uses_prefix_gv() prefix ptr @gv {
+  %gep = getelementptr inbounds i32, ptr @drop_uses_prefix_gv, i32 -1
+  %load = load ptr, ptr %gep
+  ret ptr %load
+}
+
+
+; RESULT: declare void @declaration_prefix_i32_const(){{$}}
+declare void @declaration_prefix_i32_const() prefix i32 2
+
+; RESULT: void @declaration_prefix_ptr_gv(){{$}}
+declare void @declaration_prefix_ptr_gv() prefix ptr @gv

llvm/tools/llvm-reduce/deltas/ReduceFunctionBodies.cpp

 
 void llvm::reduceFunctionBodiesDeltaPass(TestRunner &Test) {
   runDeltaPass(Test, extractFunctionBodiesFromModule,
                "Reducing Function Bodies");
 }
 
 static void reduceFunctionData(Oracle &O, Module &M) {
   for (Function &F : M) {
-    if (F.isDeclaration())
-      continue;
-
     if (F.hasPersonalityFn()) {
       if (none_of(F,
                   [](const BasicBlock &BB) {
                     return BB.isEHPad() || isa<ResumeInst>(BB.getTerminator());
                   }) &&
           !O.shouldKeep()) {
         F.setPersonalityFn(nullptr);
       }
     }
 
-    // TODO: Handle prefix data and prologue data
+    if (F.hasPrefixData() && !O.shouldKeep())
+      F.setPrefixData(nullptr);
+
+    // TODO: Handle prologue data
   }
 }
 
 void llvm::reduceFunctionDataDeltaPass(TestRunner &Test) {
   runDeltaPass(Test, reduceFunctionData, "Reducing Function Data");
 }