[PATCH] InstCombine: propagate nonNull through assume

[Ramkumar Ramachandra]

Drop the deref propagation, because it requires more work. Redo the
nonNull propagation so that it is correct (thanks to Hal for poking me
to test it properly).


http://reviews.llvm.org/D7107

Files:
  lib/Transforms/InstCombine/InstCombineCalls.cpp
  test/Transforms/InstCombine/assume.ll

Index: lib/Transforms/InstCombine/InstCombineCalls.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1081,12 +1081,18 @@
           cast<Constant>(RHS)->isNullValue()) {
         LoadInst* LI = cast<LoadInst>(LHS);
         if (isValidAssumeForContext(II, LI, DL, DT)) {
+          // assume( load (call|invoke) != null ) -> add 'nonnull' return attribute
+          Value *LIOperand = LI->getOperand(0);
+          if (CallInst *I = dyn_cast<CallInst>(LIOperand))
+            I->addAttribute(AttributeSet::ReturnIndex, Attribute::NonNull);
+          else if (InvokeInst *I = dyn_cast<InvokeInst>(LIOperand))
+            I->addAttribute(AttributeSet::ReturnIndex, Attribute::NonNull);
+
           MDNode *MD = MDNode::get(II->getContext(), None);
           LI->setMetadata(LLVMContext::MD_nonnull, MD);
           return EraseInstFromFunction(*II);
         }
       }
-      // TODO: apply nonnull return attributes to calls and invokes
       // TODO: apply range metadata for range check patterns?
     }
     // If there is a dominating assume with the same condition as this one,
Index: test/Transforms/InstCombine/assume.ll
===================================================================
--- test/Transforms/InstCombine/assume.ll
+++ test/Transforms/InstCombine/assume.ll
@@ -257,8 +257,45 @@
 ; CHECK: call void @llvm.assume
 }
 
+declare i32** @id(i32** %a)
 
+; Check that nonnull return attribute is applied to call
+define i1 @nonnull5(i32** %a) {
+entry:
+  %idr = call i32** @id(i32** %a)
+  %load = load i32** %idr
+  %cmp = icmp ne i32* %load, null
+  tail call void @llvm.assume(i1 %cmp)
+  %rval = icmp eq i32* %load, null
+  ret i1 %rval
+
+; CHECK-LABEL: @nonnull5
+; CHECK: call nonnull
+; CHECK-NOT: call void @llvm.assume
+; CHECK: ret i1 false
+}
+
+declare i32 @__personality0(...)
 
+; Check that nonnull return attribute is applied to invoke
+define i1 @nonnull6(i32** %a) {
+entry:
+  %idr = invoke i32** @id(i32** %a) to label %norm unwind label %lpad
+norm:
+  %load = load i32** %idr
+  %cmp = icmp ne i32* %load, null
+  tail call void @llvm.assume(i1 %cmp)
+  %rval = icmp eq i32* %load, null
+  ret i1 %rval
+lpad:
+  %res = landingpad { i8*, i32 } personality i32 (...)* @__personality0 cleanup
+  resume { i8*, i32 } undef
+
+; CHECK-LABEL: @nonnull6
+; CHECK: invoke nonnull
+; CHECK-NOT: call void @llvm.assume
+; CHECK: ret i1 false
+}
 
 attributes #0 = { nounwind uwtable }
 attributes #1 = { nounwind }

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