[Transforms] Preserve metadata when converting invoke to call.

[Meinersbur]

Summary

The changeToCall function did not preserve the invoke's metadata. Whether a call or invoke, the callee will access the same elements and therefore we can preserve the loop-parallel access metadata.

Copy the llvm.mem.parallel_loop_access from the invoke instruction before replacing it.

This fixes http://llvm.org/PR39994

Suggested-by: Moritz Kreutzer <[e-mail]>

[Meinersbur]

Add test case

[hfinkel]

lib/Transforms/Utils/Local.cpp

1973

Can you please generalize this? We should preserve much more than this. LLVMContext::MD_alias_scope and LLVMContext::MD_noalias should be preserved as well. I don't believe that any of our current metadata is invalidated by this (although only a limited number can appear on calls).

Thanks!

[Meinersbur]

• Generalize copyMetadata

[hfinkel]

I think that this is okay. There's no semantic change nor a change in control dependence. For this to cause a problem, there would need to be metadata that would change meaning or validity when the instruction changes from an invoke to a call (where the invoke is semantically equivalent to the call).

LGTM.

lib/Transforms/Utils/Local.cpp

static void changeToCall(InvokeInst *II, DomTreeUpdater *DTU = nullptr) {
   SmallVector<OperandBundleDef, 1> OpBundles;
   II->getOperandBundlesAsDefs(OpBundles);
   CallInst *NewCall = CallInst::Create(II->getCalledValue(), Args, OpBundles,
                                        "", II);
   NewCall->takeName(II);
   NewCall->setCallingConv(II->getCallingConv());
   NewCall->setAttributes(II->getAttributes());
   NewCall->setDebugLoc(II->getDebugLoc());
+  NewCall->copyMetadata(*II, LLVMContext::MD_mem_parallel_loop_access);
   II->replaceAllUsesWith(NewCall);
 
   // Follow the call by a branch to the normal destination.
   BasicBlock *NormalDestBB = II->getNormalDest();
   BranchInst::Create(NormalDestBB, II);
 
   // Update PHI nodes in the unwind destination
   BasicBlock *BB = II->getParent();

test/Transforms/PruneEH/looptest.ll

+; RUN: opt < %s -prune-eh -S | FileCheck %s
+
+declare void @nounwind() nounwind
+
+define internal void @foo() {
+  call void @nounwind()
+  ret void
+}
+
+; CHECK-LABEL: @caller
+define i32 @caller(i32 %n) personality i32 (...)* @__gxx_personality_v0 {
+entry:
+  br label %for
+
+for:
+  %j = phi i32 [0, %entry], [%j.inc, %inc]
+  %j.cmp = icmp slt i32 %j, %n
+  br i1 %j.cmp, label %body, label %exit, !llvm.loop !0
+  
+body:
+; CHECK: call void @foo(), !llvm.mem.parallel_loop_access !0
+  invoke void @foo( )
+      to label %Normal unwind label %Except, !llvm.mem.parallel_loop_access !0
+  br label %inc
+
+inc:
+  %j.inc = add nuw nsw i32 %j, 1
+  br label %for, !llvm.loop !0
+
+exit:
+  br label %Normal
+
+Normal:
+  ret i32 0
+
+Except:
+        landingpad { i8*, i32 }
+                catch i8* null
+  ret i32 1
+}
+
+declare i32 @__gxx_personality_v0(...)
+
+!0 = distinct !{!0}